WATER QUALITY INVESTIGATIONS
LIKE MICHIGAN BASIN
      LAKE  CURRENTS
                    A TECHNICAL REPORT CONTAINING BACKGROUND DATA



                        FOR A WATER POLLUTION CONTROL PROGRAM.
       FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
           GREAT LAKES REGION, CHICAGO, ILLINOIS
                  NOVEMBER 1967

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                               CONTENTS



Chapter

             Foreword	   xi

   1         SUMMARY	    1

   2         PHYSICAL SETTING

               Location and Description	    4
               Previous Studies	    6
               Geology	    7
               Physiography and Sediments	   11
               Hydrology	   12
               Lake Levels	   15

   3         INTRODUCTION TO LAKE CURRENT STUDIES

               General Considerations	   17
               Diffusion	   18
               Turbulent Mixing	   18
               Advection	   21
               Meteorology	   22
               Possible Fate of Pollutants	   23
               Previous Studies	   24
               Procedures	   25
                 Temperature Studies	   26
                 Tracer Methods	   26
                 Fixed-Position Current Metering	   26
                 Equipment Testing	   28
               Description of Test Studies	   28
                 Results of Test Studies	   28
               Reliability	   30
               Mooring Characteristics	   31
               Operational Characteristics	   31
               Flow Characteristics	   37
               Winds and Currents	   37
               Correlation Between Meters at one Station	   38
               Significance of Findings	   44
               Summary of Test Studies	   44

   4         METHODS FOR MOORINGS, INSTRUMENT CHECKS, FILM
              PROCESSING AND FILM CONVERSION

               Introduction	   46
               Mooring Systems	   W>
                                         U.S. Environmental Protection Agency
                                         Region 5, Library (PL-12J)
                                         77 West Jackson Boulevard, 12th Ftoflf
                                         Chicago, JL  60604-3590

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                         CCHTEMTS (Continued)
Chapter                                                            Page

   4         METHODS FOR MOORINGS, INSTRUMENT CHECKS, FILM
              PROCESSING AND FILM CONVERSION (Continued)

               Film Processing	  66
               Format for Film Reading	  75
               Tape Data Format	  76

   5         CURRENT METER FILM PROCESSING

               Specifications	  78
               Initial Processing	  80
               First Pass Program	  82
               Second Pass Programs	  84
                 Six-Hour Averages	  84
                 Histograms	  85
                 Envelopes	  85
               Spectral Analysis	  88
                 Formulas	  90
                 Cross Spectrum	  91
               Graphing	  92
               Third Pass Program	  93
                 Trajectory Programs	  93
                 Maps	  93
               Temperature Data.	  93
               Drogue Surveys	  96

   6         CURRENT STUDIES

               Introduction.	 101
               Data Compilation	 102
               Net Flows	 110
               General Circulation Patterns - Surface	 120
               General Circulation Patterns - Subsurface	 127
               Spectral Analysis	 135
                 Summary	 173
               Monthly Histograms	 174
               Six-Hour Averages	 176
               Two-Hour Envelopes	 178
               Flow at Straits of Mackinac	 179
               Summary of Lake Currents	 179
                                  ii

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                         CCMTENTS (Continued)



Chapter                                                            Page

   7         TEMPERATURE STUDIES

               Introduction.	  183
                 Definitions	  183
               Previous Studies	  l&k
               Methods of Study	  186
                 Instruments	  186
                 Bathythermograph Surveys	  189
                 Temperature Recorder Data	  217
               Results - BT Surveys	217
                 Fall, 1961	217
                 Winter, 1961	  217
                 Spring, 1962	220
                 Summer and Fall, 1962	  220
                 Spring, 1963	  221
                 Summer, 1963	  221
                 Discussion	221
               Results - Temperature Recorder  Data	223
                 Internal Waves.	  223
                 Analog Records	230
               Summary	  230

   8         DROGUE STUDIES

               Introduction	  2$k
                 Equipment	  23k
                 Field Methods	  238
               Analysis Methods	  2^0
               Description of Experimental Results	  240
               Characteristics of Diffusion.	25^
               Theoretical Models of Pollutant Diffusion from
                 Continuous Sources	  28l
               Prediction of Pollution Distribution	28*4-
               Discussion	  295
               Summary	  295

   9         METEOROLOGICAL STUDIES

               Introduction	297
               Instrumentation and Collection  of Data	297
               Climatology of Surface Pressures and  Winds	  307
               Data Analysis and  Discussion	  308
               Lake Breeze Phenomenon	  314
                                 iii

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                         CONTENTS (Continued)



Chapter                                                            Page

   9         METEOROLOGICAL STUDIES (Continued)

               A Comparison of Lake Wind to Land Wind ............. 31k
               Wind Spectra ....................................... 320
               Summary. ... ........................................ 324

  10         CORRELATION OF WIND, CURRENT, AND TEMPERATURE
              IN SUMMER ........................................... 325

  11         RELATIONSHIP TO WATER USE AREAS

               Introduction ....................................... 351
               Water Use Areas Along Shore ........................ 352
               Water Use Areas in the Lake ........................ 353
               Significant Factors ................................
             ACKNOWLEDGMENTS ...................................... 356

             REFERENCES ........................................... 357
                                  iv

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                                TABLES
Number                          Title                              Page

 2-1         Tributary Inflows	   13
 2-2         Water Budget for Lake Michigan	   14
 2-3         Computed Periods of the First Five Modes	   16
 3-1         Current Meter Readings in Each Quadrant	   43
 4-1         Specifications of Metering Equipment	   65
 k-2         Specifications of Mooring Materials	   65
 4-3         16 nm Film Data Identification Sheet and Log	   6?
 4-4a        Inspection Sheet-Current Meters Tear-Down	   68
 4-4b        Inspection Sheet-Current Meters Build-Up	   69
 4-5a        Inspection Sheet-Temperature Recorder Tear-Down	   70
 4-5b        Inspection Sheet-Temperature Recorder Build-Up	   71
 4-6a        Inspection Sheet-Wind Recorder Tear-Down	   72
 4-6b        Inspection Sheet-Wind Recorder Build-Up	   73
 5-1         Format Six-Hour Averages	   86
 5-2         Sample Format of Histogram	   87
 6-1         Timing Accuracy of Clocks	101
 6-2         Current Meter Records	105
 6-3         Current Meter and Wind Recorder	 Ill
 6-4         Questionnaire	 113
 6-5         Conversion Factors	Ilk
 6-6         Drogue Variations	115
 6-7         Current Spectra Data	 165
 6-8         Histogram	175
 6-9         Six-Hour Average Winds	177
 6-10        Cross Section of the Straits of Mackinac	180
 6-11        Average Speed and Direction in the Straits	180
 7-1         Degree of Accuracy of Instruments	189
 7-2         Temperature Data and Station Location of Cruises	 214
 7-3         Schedule of Cruises	216
 8-1         General Information on Experimental Runs	245
 8-2         Values of Characteristics of Diffusion	264
 9-1         Lake Michigan Wind Data	299
 9-2         Ratio of Buoy and Ship Wind Speeds	 311
 9-3         Average Deviation of Buoy and Ship Wind Directions... 311
 9-4         Histogram of Winds - Station 5	 312
 9-5         Wind Spectra Data	 322
10-1         Position of Stations	 335
10-2         Correlation Table of Standing Poincare Waves	 348
10-3         Correlation Between Temperature 'Waves' and Currents. 349

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                               FIGURES
Humber                          Title                              Page

 2-1         Drainage Basin	   5
 2-2         Geologic Map	   8
 2-3         Bathynetric and Physiographic Map	   9
 2-4         Bottom Sediments	  10
 3-1         Telemetry Current Meter Locations	  29
 3-2         95 Percent Confidence Limits	.	  32
 3-3         Speeds at 18 and 27 Meters	  33
 3-4         Current Meter Speeds	  34
 3-5         Direction at 18 and 27 Meters	  35
 3-6         Direction at 27 and 36 Meters	  36
 3-7         Histogram of Speed at Three Levels	  39
 3-8         Savonius Rotor Calibration	  40
 3-9         Polar Diagram - 18 m	  4l
 3-10        Polar Diagram - 27 m	  42
 4-1         Station Diagram - Sunnier	  47
 4-2         Typical Current Station	  48
 4-3         Recovery Buoy System	  50
 4-4         Link and Line Storage Case	  51
 4-5         Typical Current Station - Winter	  52
 4-6         Subsurface Buoy	  53
 4-7         Temperature Recorder	  54
 4-8         Current Meter	  55
 4-9         Anchors	  56
 4-10        Instrument Line Components	  57
 4-11        Rigid Bridle	  58
 4-12        Navigation Light	  59
 4-13        Wind Recorder	  60
 4-l4        Heavy Duty Anemometer	  6l
 4-15        Instrument Buoy	  62
 4-l6        Buoy and Float	  63
 4-17        Camera Loading Diagram	  74
 5-1         Compass and Vane Angle Deflection	  82
 5-2         Major Axis of Positive Angles	  83
 5-3         Inertia! Type Rotation	;....  89
 5-4         Format of Trajectory Program	  94
 5-5         Format of Mapping Program	  9?
 6-1         Histogram of Blurring	103
 6-2         Lake Michigan Current Meter Station Locations	104
 6-3         Current Direction Phase Shift - Station 8	117
 6-4         Winter Circulation, N-HW Winds	121
 6-5         Winter Circulation, S-SW Winds	122
 6-6         Summer Circulation, N-NE Winds	123
 6-7         Summer Circulation, S-SW Winds	124
                                  vi

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                         FIGURES (Continued)
Number                          Title                              Page

 6-8         Subsurface Net Flows, 60 Meters	128
 6-9         Subsurface Net Flows, 90 Meters	129
 6-10        Subsurface Net Flows, 120 Meters	130
 6-11        Subsurface Net Flows, 150 Meters	131
 6-12        Subsurface Net Flows, 180 Meters	132
 6-13        Subsurface Net Flows, 210 Meters	133
 6-14        Subsurface Net Flows, 240 Meters	 134
 6-15        Winter Current Spectra - Lake Michigan	136
 6-16        Summer Current Spectra - Lake Michigan	137
 6-17        Spectra of Components, Sta. 9, 15 m	138
 6-18        Spectra of Components, Sta. 9, 30 m	 139
 6-19        Spectra of Components, Sta. 9, 90 m	140
 6-20        Spectra of Components, Sta. 10, 10 m	141
 6-21        Spectra of Components, Sta. 10, 15 m	142
 6-22        Spectra of Components, Sta. 13, 10 m.	 143
 6-23        Spectra of Components, Sta. 13, 30 m	144
 6-24        Spectra of Components, Sta. 13, 60 m	145
 6-25        Spectra of Components, Sta. 17, 10 m	146
 6-26"        Spectra of Components, Sta. 20, 15 m	147
 6-27        Spectra of Components, Sta. 20, 90 m	148
 6-28        Spectra of Components, Sta. 29, 15 m	149
 6-29        Spectra of Components, Sta. 29, 60 m	150
 6-30        Spectra of Components, Sta. 31, 10 m	151
 6-31        Spectra of Components, Sta. 31, 15 m.	152
 6-32        Spectra of Components, Sta. 31, 22 m	153
 6-33        Spectra of Components, Sta. 31, 30 m	154
 6-34        Spectra of Components, Sta. 40, 60 m.	155
 6-35        Spectra of Components, Sta. 41, 10 m	156
 6-36        Spectra of Components, Sta. 4l, 90 m	 157
 6-37        Spectra of Components, Sta. 41, 120 m	158
 6-38        Spectra of Components, Sta. 54, 10 m	159
 6-39        Spectra of Components, Sta. 54, 22 m	160
 6-40        Spectra of Components, Sta. 54, 30 m	l6l
 6-41        Spectra of Components, Sta. 6l, 10 m	162
 6-42        Spectra of Components, Sta. 6l, 15 m	163
 6-43        Spectra of Components, Sta. 6l, 22 m	 164
 6-44        Flows at Straits of Mackinac	 l8l
 7-1         Density of Fresh Water	 185
 7-2         Bathythermograph	 187
 7-3         Temperature Recorder	 188
 7-4         Lake Michigan Cruise No.  1	 190
 7-5         Lake Michigan Cruise No.  2	 191
 7-6         Lake Michigan Cruise No.  3	 192
 7-7         Lake Michigan Cruise No.  4	 193
                                 vii

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Lake Michigan Cruise No. 11 	

Lake Michigan Cruise No. 13 	





	 19k
	 195
	 196
	 197
	 198
	 199
	 200
	 201
	 202
	 203
	 204
	 205
	 206
	 207
, 	 208
, 	 209
                         FIGURES (Continued)
Number                          Title

 7-8
 7-9
 7-10
 7-11
 7-12
 7-13
 7-14
 7-15
 7-16
 7-17
 7-18
 7-19
 7-20
 7-21
 7-22
 7-23
 7-24        Lake Michigan Cruise No. 18	 210
 7-25        Station Locations, Cruise No. 50	 211
 7-26        Station Locations, Cruise No. 51	 212
 7-27        Station Locations, Cruise No. 52	 213
 7-28        Lake Michigan Temperature Recorder Locations	 218
 7-29        Formation of the Thermocline	 224
 7-30        Internal Waves at Station 9, 15 m	 225
 7-31        Spectra of Temperature Records - 1963, Sta. 31 and 4l 227
 7-32        Spectra of Temperature Records - 1963, Sta. 8 and 11. 228
 7-33        Spectra of Temperature Records - 1963, Sta. 4 and 20. 229
 7-3^        Temperature Changes at Station 8	 231
 8-1         Drogue	235
 8-2         Drogue Surface Floats	 237
 8-3         Reference Marker	 239
 8-4         Map - Runs 1 and 2	 24l
 8-5         Map - Runs 3 and 4	 242
 8-6         Map - Runs 5 and 6	 244
 8-7         Drogue Positions (Run l)	 246
 8-8         Drogue Positions (Run 2)	 247
 8-9         Drogue Positions (Run 3)	 248
 8-10        Drogue Positions (Run 5)	 249
 8-11        Drogue Positions (Run 6)	 250
 8-12        Time Variation (Runs 1 and 2)	 251
 8-13        Time Variation (Run 3)	 252
 8-14        Time Variation (Runs 5 and 6)	 253
 8-15        Movement of Drogues and Wind Track (Run l)	 255
 8-16        Movement of Drogues and Wind Track (Run 2)	256
                                 viii

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                                   FIGURES (Continued)
          Number                          Title

           8-17        Movement of Drogues and Wind Track (Run 3)	257
*          8-18        Movement of Drogues and Wind Track (Run 5)	 258
           8-19        Movement of Drogues and Wind Track (Run 6)	 259
           8-20        Standard Deviation of Drogues to Initial Position
                         (Runs 1 and 2)	 26l
           8-21        Standard Deviation of Drogues to Initial Position
                         (Run 3)	 262
           8-22        Standard Deviation of Drogues to Initial Position
                         (Runs 5 and 6)	 263
           8-23        Mean Separation (Runs 1 and 2)	 266
           8-24        Mean Separation (Runs 2 and 3)	 267
           8-25        Mean Separation (Runs 3 and 5)	 268
           8-26        Mean Separation (Run 6)	 269
           8-27        Mean Square Separation Versus Time (Runs 1 and 2).... 271
           8-28        Mean Square Separation Versus Time (Runs 2 and 3).... 272
           8-29        Mean Square Separation Versus Time (Runs 3 and 5).... 273
           8-30        Mean Square Separation Versus Time (Run 6)	 274
           8-31        Standard Deviation-Pair Versus Time (Run l)	 276
           8-32        Standard Deviation-Pair Versus Time (Run 2)	277
           8-33        Standard Deviation-Pair Versus Time (Run 3)	 278
           8-34        Standard Deviation-Pair Versus Time (Run 5)	279
           8-35        Standard Deviation-Pair Versus Time (Run 6)	280
           8-36        Steady-State Distribution of Concentration
                         (ui = 0.2)	 287
           8-37        Steady-State Distribution of Concentration
                         (u^ - 0.4)	 288
           8-38        Relative Concentration (yx = 0)	 289
           8-39        Relative Concentration (yj^ = 2)	 290
           8-4O        Relative Concentration (y^ = 4)	 291
           8-41        Non-Steady Distribution (yx = 0(0.2))	292
           8-42        Non-Steady Distribution (y^ = 0(0.4))	 293
           8-1*3        Relative Concentration	 294
           9-1         Network Stations „	 298
           9-2         Calibration	 302
           9-3         Instrument Buoy	 303
           9-4         6-Hour Averages -  Station 5	 305
           9-5         2-Hour Envelope	 306
g          9-6         Lake Michigan Printout	 309
           9-7         Current Trajectories	 313
           9-8         Weather Map 12C, August 20, 1963	 315
           9-9         Weather Map 12C, August 21, 1963	 3l6
*          9-10        2-Hour Envelope -  Station 8	 317
           9-11        2-Hour Envelope -  Station 18	 318
                                            ix

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                         FIGURES (Continued)
Number                          Title

  9-12       Lake Michigan Versus Shore Wind Direction	 319
  9-13       Lake Michigan Versus Shore Wind Speed	 321
  9-14       Spectra, Station 13	 323
 10-1        Temperature Distribution Between Milwaukee and
               Muskegon	 326
 10-2        Distribution of 10° Isotherm, Milwaukee to Muskegon.. 328
 10-3        Qualitative Representation of Kelvin and Sverdrup
               Waves	 329
 10-4        Transverse Standing, Kelvin, Sverdrup and Poincare'
               Waves	 330
 10-5        Comparison of Lake and Land Wind Speeds	 331
 10-6        Comparison of Lake and Land Wind Speeds	 332
 10-7        Wind, Temperature, and Currents - Station 15	 336
 10-8        Wind, Temperature, and Currents - Station 15	 337
 10-9        Wind, Temperature, and Currents - Station 17	 338
 10-10       Wind, Temperature, and Currents - Station 17	 339
 10-11       Wind, Temperature, and Currents - Station 17	 340
 10-12       Wind, Temperature, and Currents - Station 20	 34l
 10-13       Wind, Temperature, and Currents - Station 20	 342
 10-14       Wind, Temperature, and Currents - Station 20	 343
 10-15       Sections Across a Uninodal and a Trinodal Wave	 344

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                               FOREWORD

       In I960 the Federal Government undertook the task of determining
the sources of wastes  responsible  for degrading  the quality of Great
Lakes waters, evaluating the effects of such  wastes on the quality and
uses of the receiving waters, and developing comprehensive water pollu-
tion control programs to enhance and protect  their quality.  To better
understand the physical mechanisms by  which pollution-laden waters mix
with and are  transported by lake currents, an extensive study of these
phenomena was incorporated into the investigations.  An account of part
of this monumental  task — relating  to  circulation,  diffusion,  and
seasonal changes in physical parameters in Lake Michigan — is given in
the report which follows.

       In view of the oceanographic scale of the study, instruments and
data processing techniques  recently developed for ocean investigations
were utilized. A lake-wide deployment of recording instruments produced
a long series of records of  current  and water  temperature at several
depths from more than 30 stations covering  all of Lake Michigan.  Wind
was also  recorded at some of the stations.  This is the first occasion
on which physical events and processes in so large a natural water body,
fresh or marine,  have been monitored for an interval of nearly 2 years
with so close a network of recorders.

       While the need to solve immediate  practical  problems  provided
the impetus for the investigation, the invested effort has yielded much
new information of scientific interest, and this  provides yet  another
example of the advantages to be  gained  by  close association  between
applied and so-called pure research.

       Practical questions of great urgency concerning  the fate of the
Great Lakes await answers; and it is  in the  light  of  these concerns
that the appearance of this report must chiefly be welcomed.  Its find-
ings — on such matters as the  dominant summer and winter  circulation
patterns, the differences between inshore and offshore current regimes,
and the rates of  turbulent dispersal — will have important bearing on
the interpretations to be placed on water quality changes. There can be
no doubt that this  and subsequent  reports by the Great Lakes-Illinois
River Basins Project will  be indispensable  source  books  for  future
water planning in the Great Lakes region and  for other  scientific and
engineering studies.
                                  Clifford H. Mortimer, D.Sc., F.R.S.
                                  Director, Center for Great Lakes Studies
                                  University of Wisconsin-Milwaukee
                                  xi

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                              CHAPTER 1

                               SUMMABT
       Lake Michigan is  the third  largest of  the Great Lakes and the
only one lying wholly within the United States.  It has a  surface area
of 58,016 square kilometers, an average depth of 8k meters, and a total
volume  of £,878 cubic  kilometers.  In general,  the  Lake is oriented
along  the  north-south  axis,  the  northern  part of the Lake curving
gently to the northeast.  The Lake is  divided  into  two basins by two
parallel ridges running  In  an  easterly  direction  from Milwaukee to
Grand Haven.  The southern  basin  is  smaller  and  shallower than the
northern basin with a maximum depth of  160 meters.  The northern basin
is longer and narrower. In it is located the deepest point in the Lake,
281 meters.

       The energy inputs into the Lake responsible for mixing and move-
ment of its waters are derived almost  exclusively  from meteorological
disturbances.  Whereas in small  lakes the transfer  of energy  through
wind stress tends to drive the surface water out, in Lake Michigan this
process is complicated by  such factors  as the Corlolis  effect of the
earth's rotation, nonuniformity of wind stress, and by the variation in
atmospheric pressure on the water surface from the  progression of high
and low barometric pressure areas passing over the Lake. Although there
are an infinite variety and frequent changes in both direction and mag-
nitude of energy input, certain patterns of water  movement  have  been
observed.  These patterns result from the fact that seasonally there is
a dominance of winds from one general direction.

       Both water movements and rate  of mixing are  materially  influ-
enced by the formation of thermoclines, or zones of  temperature  tran-
sition between two layers of water  which  differ  in  temperature  and
density.  Once stabilized  at  depths  which  prevent  storm turbulence
interruption, summer thermoclines effectively  prevent mixing of waters
of the epilimnion (upper layer) with  those of the hypolimnlon  (bottom
waters).  Reverse thermoclines, involving  very  small density changes,
are found in winter but  usually  at  greater  depths  than  in  summer
because they offer less resistance to wind mixing.

       Thermal bars, phenomena resulting from  a difference in tempera-
ture between  adjacent waters along a vertical plane, occur both in the
spring and in the fall in shallow  waters  parallel to  the  shoreline.
Like the thermocline, a thermal  bar prevents  mixing between the shal-
low waters along the shore and the deeper Lake waters.

       Temperature records  from  many  of  the  stations  showed  that
internal waves were almost always present on the thermocline.  Spectral

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analysis of the temperature  clearly  established  several  frequencies
for these waves,  the  most  dominant  being  in the 16 to 18-hour fre-
quency.  This corresponds closely to the inertia! period  for the lati-
tude.  The inertial period is related  to the rotation  of  the  earth,
being 2k hours at 30° latitude and varying as the sine of the latitude.

       Four basic  patterns of  water  movements  occur  in  the  upper
layers, two in winter and two in summer.  Each current pattern is some-
vhat modified by the nearshore currents.  The shore  currents appear to
be dominated by the prevailing or net winds.  One winter  pattern shews
the influence of north-northwest  winds.  The currents  generally  move
southerly along the east shore and  northerly  along  the  west  shore.
There Is a rotation in the southern basin with some  of  the  northerly
flow moving eastward in the general  area of Milwaukee  and Joining the
southerly flow along the east side  below Grand Haven.  A similar gyre,
elongated in shape, exists in the  northern basin.  It extends  from an
area north of Milwaukee to  the Straits of Nackinac and also circulates
in a clockwise direction.  This pattern may be expected during 25 to 30
percent of the year.

       The other  winter  pattern  occurs  only 20 to 25 percent of the
year, principally between January and April.  In this pattern the gyres
in the northern and southern basins are reversed and   rotate  counter-
clockwise with principal flows north  along  the east  shore  and south
along the west shore.

       The dominant summer pattern is created by  south-southwest winds
occurring nearly bO percent  of the year.  Much  obscured  by  rotating
currents associated with internal waves, the picture  of general circu-
lation may be defined roughly as follows:  In  the southern  basin  the
counterclockwise gyre exists, but Inshore currents on  both  the   east
and west shores are northward.  The northerly flow along the west shore
is weaker and undoubtedly fed by westerly flows  in  the deeper waters.
In the northern basin, the dominant flow is southward  in the center of
the Lake.  This southward flow splits above  Milwaukee, one part moving
east and north along the east  shore, and  the  other  moving west  and
north along the western shore.

       When under the  occasional  dominance of north-northeast  winds,
the southern basin gyre continues  In its previous counterclockwise di-
rection, but the inshore currents along both  the east and west  shores
then move  southward. This pattern, again obscured by rotating currents
associated with Internal waves, occurs about 10 percent of the year. At
such times, southward currents also prevail  along both shores  in  the
northern basin, and there is a narrow current south in the central part
of the northern basin.  This splits above Milwaukee to feed narrow cur-
rents running northward on both sides of the central southern  movement
and between the southerly currents along both shores.

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       Drogues were used to track vater masses in the following  diffu-
sion studies:   In southern  Lake Michigan, at the mouth of the Detroit
River in Lake Brie and  near Cleveland, Ohio  in  Lake Brie.  A special
study vas  also conducted in Lake Michigan in September 1961, following
the release of a large mass of polluted  vater into the  Lake from  the
Chicago River mouth.  This latter study did not use drogues; instead, a
grid of sampling points vas established In the area and the vater move-
ment and mixing were established on the basis of coliform analyses.

       Based on the diffusion studies it was concluded  that  mixing in
shallow shore waters with steady wind velocities in the range of 300 to
MX) cm/sec is relatively slow.  Under such  conditions  pollutants dis-
charged into the Lake can travel several  miles  relatively  undiluted.
Although the extent  of mixing can be calculated, the duration of winds
having the particular direction and velocity to produce maximum effects
at a particular water use point is less certain.

       The complexity  of  the  Interplay  of forces providing   energy
inputs into Lake Michigan has prevented the development of mathematical
models describing the relationship  between the direction  and velocity
of winds over land  with the associated water movements.  Nevertheless,
knowledge of the current patterns described herein should be helpful in
the site selection and design of water intakes and waste outlet instal-
lations.  Additional nore specific data are available where such a site
is near a current meter station.   However, special studies or investi-
gations should be undertaken to confirm the validity of the data at the
chosen site,  since  most of the current  metering stations were set In
deeper  waters and would not necessarily  reflect the local  effects of
Irregularities along  the shoreline; nor would they detect the presence
of a thermal bar which could prevent  the Mixing of nearshore with off-
shore waters.

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                              CHAPTER 2

                           PHYSICAL SETTIHG
Location and Description

       Lake  Michigan  is  the only one of  the  Great Lakes  that lies
wholly within the boundaries of the  United States, but it  is so large
and extends so far into the United States that it f anas a  small  inte-
rior sea.   The  Lake has a surface  area of 58,016  square  kilometers
(km2), which is equal in area to the combined  States of Hew Hampshire,
Massachusetts, Connecticut, and Rhode Island.   It has an average depth
of 8k meters (a) and a maximum depth of 28l a.   The deepest portion of
the Lake is 105 a below sea level.   Its length is k?k km and its width
is 190 km; the total length of shoreline is 2,673 km and the total vol-
ume of water is 4,878 cubic kilometers (km3).   The mean-water  surface
elevation of Lake  Michigan is 176.5 a  above sea level.   The range of
monthly mean  elevation is 2 a and the average seasonal  fluctuation is
0-30 m.

       The States bordering Lake Michigan are Illinois, Indiana, Michi-
gan, and Wisconsin.   Major  cities  located  on  the Lake are Chicago,
Illinois; Gary, Indiana;  Racine, Wisconsin;  Milwaukee, Wisconsin; and
Muskegon, Michigan.  The 1960 population of the basin was approximately
5.7 million, about 3.2 percent of the United States.   These figures do
not include the Chicago region  which is located in the  Illinois River
Basin, Figure 2-1.

       The climate of the Lake Michigan Region is  typical humid conti-
nental with  severe  winters  and warm  summers.  Temperatures increase
from north to south.   The greatest  extremes  occur  during the winter
months.  The January means for Chicago and Green Bay, respectively, are
5.5° and -9.3°C. The July means for Chicago and Green Bay, respectively
are 22.5° and 21.7°C.  The mean annual temperature of Chicago is 9.5°C,
whereas to the north at Green Bay it is 6.6°C.

       The mean annual precipitation  for the  region is  approximately
77-2 centimeters (cm),  and is higher  between April and September than
between October and March  (USLS, 8l).   The east side of Lake Michigan
receives  more  precipitation  than  the  western  side.  Precipitation
increases  with ground elevation in the basin and averages approximate-
ly 10 percent higher over upland areas than over the lakes which are  a
hundred meters lower (Day,
       Intralake shipping on  the Great Lakes  ceases around December 1
each year  because of  ice conditions.  Lake Michigan does not  usually

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    GREAT  LAKES — ILLINOIS
     RIVER  BASINS  PROJECT
     DRAINAGE  BASIN
              of
       LAKE  MICHIGAN
   U S DEPARTMENT OF THE INTERIOR

FEDERAL WATER POLLUTION CONTROL AOMIN

Great LaKes Region          Chicago,Illinois
                      FIGURE 2-1

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freeze over, except  during severe winters, but  ice conditions in such
areas as the Straits of Mackinac, eastern Lake Erie, the Welland Canal,
and the St. Lawrence River  close passage to all ships.  Winter naviga-
tion on Lake Michigan consists of  car-ferries and fuel vessels operat-
ing regularly between the major ports. The ice builds up from shore and
later may break off and become drift ice.  During severe winters,  Lake
Michigan  has been known to freeze completely over, for instance during
February 1963.   Upon breakup, drifting ice usually piles up,  in  con-
stricted areas, into ridges and windrows as high as 10 m and 13 or more
m in depth.

       The opening  date of navigation is usually early April, but  has
been as late as early May.

Previous Studies

       The  first  study  of currents in Lake Michigan was conducted by
Harrington in 1895 (36).   Field work for his  report  was carried  out
from 1892 to 189^.  Harrington released approximately 1,500  drift bot-
tles at various points in  the Lake  and recovered 203 of them at their
points of stranding on the shores. From these returns, a chart was made
showing the surface  currents.  This chart showed  two counterclockwise
gyres making up the principal circulation systems;  one in the southern
basin, and a more elongated one  in the northern  part of the Lake.   A
much smaller  elongated clockwise  gyral flow system  was located along
the western shore near Milwaukee.

       Townsend (78), in 1916, criticized  the  findings of Harrington,
and pointed  out that since only the point of release  and the point of
recovery of drift  bottles are known,  it is not possible  to know  the
path  taken  by  the bottles.   In 1932-36,  Deason (25)  studied  Lake
Michigan  currents using  drift bottles, and his  conclusions generally
followed Harrington's.

       Church (l8, 19), in 19^2 and 19^5, made a comprehensive study of
the  annual  temperature  cycle  in  a number of cross-sections of Lake
Michigan.  His temperature data tended to support Harrington.  In 195^-
55, the U. S. Bureau  of  Commercial Fisheries  completed  an intensive
study of surface currents using drift bottles and drift cards (Johnson,
45).  Out of 6,000 releases, 3,000 were recovered.   The results of the
1954 study were inconclusive; in  general,  however, the drift was west
to east and north to south movements about equal in magnitude.  A simi-
lar pattern was  found in 1955,  except that  the  drift in the eastern
areas was mainly from the south.  Ayers et al.,  (2)  1958,   published
the results of a series of synoptic surveys completed in 1955> in which
they used drift  bottles  and  applied  a  modification of the dynamic-

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heights aethod to determine the  circulation  of  Lake  Michigan.   The
results  of  the  drift  bottle   study   showed  good  agreement  with
Harrington's study.

       As pointed out by  Ayers et al., the winds  were westerly, which
he considers as being the norm for the summer months. Except for Church
(19)  1942,  inferred from temperature, none of the  above  researchers
reported on wintertime lake circulation.

Geology

       Various phases of the geology of Lake Michigan have been report-
ed, but only the more recent  will be  mentioned here (see Figures 2-2,
2-3, and 2-M-

       In 1958, Hough (40) showed that  glacial till is a common bottom
material  and  that  wave  action in shallow water has winnowed out the
finer grains, leaving a concentration of gravel Just offshore.  Shepard
(71), pointed out that glacial erosion at the  north end of the Lake is
indicated by  fiord-like valleys, by rocky islands, and by complex bot-
tom topography.   Thwaites  (77)   related the ridges  around  the lake
shore and on  its  floor  to the presence of resistant dolomites, lime-
stones, and sandstones, and the  deeper areas  to less-resistant shales
and evaporites.  The position and strike of the outcrop of these alter-
nating beds of hard and soft strata are controlled by the southeasterly
dip into the structural  basin  that  underlies  the State of Michigan.
Bsery (30)   described  the  bathymetry  and  bottom  deposits  of Lake
Michigan•

       Lake Michigan  is  located entirely within a region of Paleozoic
rocks (Fig. 2-2) that  form part of a structural  basin centered in the
State of Michigan.   To the northwest are Pre-Cambrian  rocks that com-
prise part  of  the Canadian  Shield,  onto  which  the Paleosoic rocks
onlap.  Due to the structure of the area, the oldest rocks  crop out in
the west; the  rocks become progressively younger toward the structural
basin.   The strike  of  these rocks generally follows the long axis of
the Lake.

       In the north,  the floor  of the  Lake is made up of evaporites,
limestones,  and shales.  The southern Lake basin is floored by shales.
Very few  outcrops  of these  rocks  exist, however, because  they  are
mantled by  glacial  debris  deposited  during  the  Pleistocene Epoch.
Although the Lake Michigan area has been an area of low topography with
numerous invasions of the sea,  it was the glaciers  that formed during
the Pleistocene Epoch which shaped  the  lake  itself.   These glaciers
developed to  the north  and migrated  southward,  gouging out the Lake
Michigan Basin.   The topography of the region has been little modified
since.

-------
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NORTH
DIVIDE
SOUTH
             LEGEND
     CONTOUR  IN METERS
          27O
          240	•	
          210
          I80	
          I 50  	••-	
          120	
           90
           60	
           30
                                                      Ar«o of Complex Bothymetry
                                                       Percent of Area
                                                     20  40   60  80
                                                     — —Sea Level
   0   16  32 48
               Km.
      Scale
                   After Emery,1951
                                                GREAT  LAKES — ILLINOIS
                                                 RIVER  BASINS PROJECT
                                                   LAKE     MICHIGAN
                                                 BATHYMETRIC  CHART
    U S DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL AOMIN
Great Lakes Region          Chicago Illinois
                                                                   FIGURE 2-3

-------
.43
            88°
 87'
86'
85'
                                   BOTTOM  SEDIMENTS
                                          After Emeryrl95l
                                                              42°-
          88°
           i
87°
                                           GREAT LAKES —  ILLINOIS

                                             RIVER BASINS  PROJECT
 SEDIMENTS OF LAKE  MICHIGAN
                                          'U S DEPARTMENT OF THE INTERIOR

                                       FEDERAL WATER POLLUTION CONTROL AOMIN

                                       Great Lakes Region          Chicago,Illinois
                                                              FIGURE 2-4

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Physiography and Sediments

       Lake Michigan  can be divided  into five areas  having different
physiographic characteristics.  However, for water quality purposes the
Divide Area is not classified separately.  These areas are termed South
Basin, Divide, lorth Basin, Straits Area, and Green Bay  (Fig. 2-3).

       The South Basin extends  frost the southern  tip of the Lake to a
line connecting Milwaukee and Grand Haven.   This area has gentle topo-
graphy, suggesting excavation of a thick homogeneous formation, follow-
ed by silting caused by glacial outvash.   The bottom materials consist
of sand  along the shore  and on the beaches,  gravel largely  at water
depths between 15 and  30 m, and mud in deeper water.    Hough (4O)  as-
cribes this  distribution  to  the  winnowing  of  glacial till by wave
action,  whereby gravel is a lag deposit,  sand is carried  landward to
the shore,  and mud remains in  suspension  until it reaches  the quiet
water of the Lake bottom.

       The next physiographic area is the Divide, which  consists of two
separate ridges.  According to Thwaltes  (77), 1947, the southern ridge
marks the position of the resistant Traverse limestone and the northern
one the resistant Dundee  limestone.   These ridges may  also consist in
part of recessional moraines.   Bottom notations on various charts show
the presence of boulders and clay near  the west  shore, probably indi-
cating glacial till.   Sand forms a belt between  water  depths of about
15 and 90 m on  the west side and from shore to 38 m  on the east side.
The few bottom  notations in the middle of the  section  show mud almost
exclusively.   Most likely,  the tops of the ridges consist  of coarser
material.

       The third  area,  the North  Basin,  extends north  from a  line
between Manitowoc  and  Manistee  to a line between Frankfort and Mani-
stique.   It consists of one main basin which,  unlike the South Basin,
is irregular in shape.  The topography is suggestive of  excavation of a
thick nonhomogeneous rock  with only slight mantling by  later sediment.
The maximum lake  depth is found in this basin.   This section  appears
most likely  to  have  been  excavated  by glacial erosion.  Along both
shores  is a belt of rock that, on the west side, ranges in width up to
about 2k km.  Gravel is probably  common  in  the rock area.  A belt of
sand of varying width borders the rock.  In deep water,  chart notations
show mud exclusively. In each of the three physiographic sections which
comprise the main area of the lake, coarser sediments are better repre-
sented on the east shore.

       The fourth area, the Straits Area, is one of very irregular top-
ography, accounted for by the presence of alternating belts of hard and
soft rocks that were  oriented  perpendicular  to  the movement  of the
                                   11

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glacier*. The deep depressions and rocky ridges are similar to the gla-
cial erosional topography found in the fiord coasts of Norway.

       In the Straits Area is the outlet of Lake Michigan. Although the
narrowest point is in the Straits of Mackinac, the shallowest diride is
located 12 km westward, well within the wider part of the Lake. Between
these two points, and extending  eastward into  Lake Huron, is a narrow
canyon, approximately 8 km  wide and 39 • deep.   The complexity of the
bottom contours is  matched  by  the  -variety of  the bottom materials.
Figure 2-k shows that rock occurs around  the shores of all islands and
at the tops of  submerged hills.   Sand is abundant only in three large
areas near the extreme end of the lake.  lead  occupies the  depressions
and lower areas.

       The Green Bay Area is fairly shallow,  averaging about 2k a with
a maximum of 50 m near one of the entrances. The north end of the Green
Bay section is exposed to the waves of Lake Michigan and,  as a result,
its floor consists principally of rock.  Within the area of quiet water
at the south end of Green Bay, the sediments have a more normal distri-
bution, with rock along the shore, sand generally paralleling the rock,
and mud farthest offshore.

Hydrology

       The water balance for Lake Michigan can most easily be determin-
ed by the water budget. Table 2-1 lists all the gaged tributary streams
into Lake Michigan. The total inflow as estimated by the USGS (79), av-
eraged from the total gaged and ungaged stream basins, is 1,102 m3  per
second (33,900 cfs). Table 2-2 lists the essential factors in the water
budget and shows that the computed outflow at the Straits of Mackinacis
about 1,13^ m3 per second (1*0,000 cfs).

       The extent of ground  water exchange  is not known,  but is con-
sidered as minor in the computations.

       The above figures  could be  checked by  adding the  Lake  Huron
inputs plus the inflow at the St. Marys  River and figuring the balance
at the Detroit River.   The  difference  should  approximate  the  Lake
Michigan contribution.

       Using figures  for precipitation  and  evaporation by Ownbey and
Willeke (59) and inflow figures for the Michigan-Huron Basin,  the dif-
ferences are considerable.   Bergstrom and Hanson (8)  report that  the
combined tributary inflow for  the two basins  is 2,073 »^/sec  (73,200
cfs).   Assuming  the Lake Michigan  inflow  figures  are valid  (1,101
m3/sec), the Lake Huron tributary inflow can be estimated at 972 m3/sec
(34,300 cfs).   Precipitation  minus  evaporation  is estimated  at 1*72
                                   12

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                                TABLE 2-1




                            TRIBUTARY HFLOH8*
AVERAGE FLOW
RIVKR
Michigan
Boardaan
Little Manistee
Manistee
Big Sable
Per* Marquette
White
Muskegon
Grand
Black
Kalamaxoo
Fav Pair
St. Joseph
Menoainee
Ford
Eccanaba
Indian
Black
Wisconsin
Peshtigo
Oconto
Fox
Milwaukee
Cedar Creek
Indiana
Burns Ditch
GPS

186
162
1,933
137
608
367
1,889
3,362
1*5.2
1,269
373
3,025
3,098
32V
895
369
25-1

832
569
4,140
381
62.3

127
M3/31C

5-3
k.6
54.7
3-9
17.2
10.4
53-5
95.2
1.3
35-9
10.6
85.7
87.7
9.2
25.3
10. v
0.7

23.6
16.1
117.2
10.8
1.8

3.6
GAGED
8Q MI

223
200
1,780
127
709
380
2,350
4,900
65.8
1,600
390
3,666
3,790
450
870
302
28

1,124
678
6,150
686
121

160
AREA
SQ KM

577.6
518.0
4,610.2
310.8
1,836.3
984.2
6,086.5
12,690.0
170.4
4,144.0
1,010.1
9,494.9
9,816.1
1,165.5
2,253-3
782.2
72.5

2,911.2
1,756.0
15,928.5
1,776.7
313.4

414.4
YEARS OF
RECORD

13
9
14
23
26
8
*3
39
5
35
14
35
53
11
24
27
14

12
54
69
51
35

17
  Totals
24,205.6  684.7
30,749.8
79,622.8
«USGS (79)
                                     13

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                                 TABLE 2-2

                        WATER BUDGET FOR LAKE KICHIGAU
 Positive Contribution
Tributary Inflow
Precipitation
Ground Water
                    ^
                           AVERAGE FLOW
                                        (1)
                         M3/SEC
                         1,104
                         1,374
                                    GPS
39,000
48,500
                                                    AVERAGE FLOW
                                                                 (2)
                M3/SEC
1,101
1,466
   11
                 CFS
38,900
51,750
   400
 Negative

    Evaporation
    Diversion (1940-
      1960 avg)
                         2,478
                     1,286
                        92
                                  87,500
45,400
 3,240
  994
   92
35,100
 3,240
 Net Outflow
                     1,378

                     1,100
48,640

38,860
1,492
52,710
(l)  Precipitation and evaporation from Ounbey and Willeke (59)-
(2)  Precipitation, evaporation, and groundvater from Bergstrom and
       Hancon (8), estimated at one-half the Michigan-Huron total.
(3)  Include* ungaged tributary inflow.

-------
m3/sec and the St. Marys  River inflow (66 year average, USLS) is 2,079
m3/aec   (73,400 cfs).   The St. Glair River outflow from Lake Huron  (66
year average, USLS) is 4,993 »3/sec  (176,300 cfs).   The resulting out-
flow for Lake Michigan is computed at 1,470 m3/sec (51,906  cfs).  Obvi-
ously the precipitation-evaporation  figures are the greatest sources of
error in the computations, and this  problem is far from resolved today.
The conservative  figures of Ownbey  and Willeke (59)  were  used in most
of the Lake Michigan  calculations   for  the  remainder of  the  report.

Lake Levels

       Lakes Michigan-Huron  are considered  hydraulically  as one lake.
The reference datum for Lakes Michigan-Huron water surface, referred to
as "Low Water Datum," is 576.80 feet (175.8l m)  above sea  level on the
International Great Lakes Datum of 1955- The lowest monthly mean levels
during the past  105  years have occurred  in the past few  years, being
0.42 m below the datum in March 1964.   The highest levels  occurred in
June 1886 when the water was 1.56 m  above the datum.  The extreme range
is 1.98 m,  or the  greatest of all  the Great Lakes ranges.  While  no
doubt the prevailing drought  conditions  contributed to  the   extreme
lowering of  the  Michigan-Huron Basin in 1964,  during the same period
neither Lake Erie nor Lake Ontario experienced a similar drop in level,
even though the drought conditions were very  similar in their drainage
basins.  It is probable that changes made by man in the outlet channels
have contributed to  the extreme range in the Michigan-Huron water lev-
els; the flow  from Lake Superior is regulated by  controlling locks on
the St. Marys  River and  is  not subject to changes in the  connecting
channels.

       In addition to the long-term  variations,  which reflect changes
in storage volume, Lake Michigan has tides  (lunar and solar), seiches,
and surges.  These short period fluctuations do not result  in a  change
in volume, but a change In the water level shape. In general, tides are
minor,  7.2 mm  lunar and  3-1 to 6.3  mm solar  (Hutchinson, 44).  The
seiches rarely exceed 0.3 m in height.  The first five seiche  periods,
of the longitudinal seiche, are shown in Table 2-3 (Rockwell, 67).

       In a spectral study of surface level fluctuations, Mortimer (55)
interpreted dominant  spectral  peaks  at approximately  9-0, 5-2, 3-7,
3.1,  and  2.5  hours  as  corresponding to the first five longitudinal
modes and demonstrated a striking transverse first-mode  seiche  at 2.2
hours in the southern  half of the Lake.   In addition, he demonstrated
resonance in Green  Bay  between  the free period of oscillation of the
Bay, at approximately 11 hours,  with the lunar tide 12.4 hours and the
first Lake Michigan mode at 9.0 hours.
                                    15

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                              TAJL1 2-3

               COMPUTED PBtlGBB 
-------
                             CHAPTER  3

                IKTROIXJCTIQH TO LAKE  CURRHTT STUDIES
       The study of currents  in Lake Michigan  reported herein is part
of the overall program of investigations undertaken by the Great Lakes-
Illinois River Basins Project.   The ultimate objectives of the studies
are:  to assist in predicting  the fate  of pollutants introduced into
the Lake; to assess the effects of waste inputs on lake water quality-
effects both  local and area-vide,  both now and in the future;  and to
aid in the aaking of vise decisions  for protecting this valuable water
resource.

       Waste-bearing waters are dispersed  from a point of input to  the
Lake by some combination of three processes:  molecular diffusion, tur-
bulent mixing,  and mass  transport.   The relative Importance  of each
process depends on physical  conditions in the Lake.   For example,  in
completely quiescent waters the  predominant process would be molecular
diffusion.   Turbulence (the existence of randomly-varied water veloci-
ties) in the vicinity of the point of input will greatly accelerate  the
rate of dispersal over that effected by molecular activity alone.    If,
superimposed on this random turbulence, there is a prevailing velocity,
then the water mass as a whole, and the accompanying waste waters, will
move in  that direction.   Knowledge of the existence  (or absence)  of
such movements is essential, both for predicting the fate of pollutants
and for planning strategic  locations of waste input and  water extrac-
tion points to minimize short-circuiting.

       The objectives of the Lake Michigan current study are, then:  to
determine the variations  in physical characteristics,  temperature  and
density,  of water within the Lake;  to measure the water movement pat-
terns  over  a  period  of time; and to develop, from  considerations of
cause and  effect,  a theoretical  basis for  generalizing the observed
conditions.

General Considerations

       To comprehend the details of the data  on currents it is logical
to review the theoretical concepts and the terminology of the study.

       A pollutant which is a liquid or a suspension of small particles,
when introduced into a body of water, may be diffused  (molecular scale),
mixed  or diluted  (larger scale),  and advected  or moved  by currents
(still larger scale).   All three scales  of motion are present in Lake
Michigan.   Each will be  discussed in turn  and its   significance con-
sidered.   It will be evident by  the end of the  discussion that there
are gaps in our knowledge of these various scales.   Some of these gaps
                                   17

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hare been filled by  field investigations;  the rest await  advances in
theory and instrumentation.

Diffusion

       Molecular diffusion is a complex  random action directly associ-
ated with molecular motion and accelerated by  the thensal agitation of
individual molecules.   It is perhaps  the least  important  motion for
pollutants in  Lake Michigan in comparison vlth the  effects of larger-
scale movements.  Other  than acknowledging  its existence,   molecular
diffusion will not be considered further.

Turbulent Mixing

       Turbulent mixing is a complex random motion not directly associ-
ated with the agitation of individual molecules.   According to Corrsln
(21)  "...turbulence can be expected  in a fluid  whenever  there  is a
shearing  flow  and  the  inertia! effects are much larger than viscous
effects."  These conditions are often satisfied in Lake Michigan.  Tur-
bulence affects  the  dispersal  rate of pollutants much more than does
molecular diffusion.

       Generally speaking, "...much of the core of the turbulence prob-
lem  has  yet  to  yield  to  formal  theoretical attack" (Corrsin, 21).
Mathematical   difficulties  in  handling  nonlinear  expressions  have
greatly hampered progress;  the nonlinear!ty  Implies that there are no
simple  relationships  readily  susceptible  to mathematical treatment.
Work relating to natural waters, both salt and fresh, has been publish-
ed by  Richardson  and Stommel (6k),  Stommel (7*0,  Joseph and Sendner
(1*6), Hoble (56), and others.  In addition, there is significant unpub-
lished work by Scbonfeld of the Netherlands, Okubo of the Johns Hopkins
University's Chesapeake Bay Institute,  and others.   Recent researches
into  flow  in  stratified  fluids  are  directly  relevant to the Lake
Michigan problem, and these have been reviewed by Mortimer (5U). A good
deal  of  research  is  now  being  carried  out In this field, so long
neglected  in  comparison  with  turbulence  in homogeneous fluids, and
theoretical and experimental progress is being made.

       The wind, acting both directly and indirectly, appears to be the
chief force causing water  motion in Lake Michigan,  overcoming inertia
and stability and resulting In internal turbulence.  Wind stress on the
water surface can cause waves,  set-up,  and currents,  and if abruptly
terminated after a sufficiently long period, may result In a seiche.

       If water temperatures  are vertically  isothermal,  the wind can
stir the whole Lake.  Wind results in waves and orbital particle motion
to depths of at  least half a wave length if  thermal stratification is
                                  18

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not too strong.  If  the wind  blows from the same  direction for a few
hours,  it will cause set-up;  that is,  wind stress will drag  surface
water to the leeward  side of the Lake,  causing a measurable piling up
of water against the shore.  Mixing  will occur while  water is  moving
toward the shore  and while part of the piled-up  water is  escaping by
moving  parallel  to  the  shore  or  by  reverse  flow as a subsurface
current.   In addition,  when the wind either  stops blowing  or shifts
direction,  the piled-up water begins to move toward the  opposite side
of the Lake.   Often it surges back and forth  across the Lake  several
times with  a period determined  by basin geometry  and fluid  density;
this is called a surface seiche.  The seiche results in further, though
less Important, mixing. If there is significant density stratification,
an internal seiche may also be started.  The internal seiche,  like the
surface seiche,  is a wave form at a density interface,  though in this
instance there is water above  and below,  while for the surface seiche
air is  above  and  water  below.   Periods of internal seiches nay  be
longer and the amplitudes greater than surface seiches.  Because of the
large amplitudes, internal seiches can accomplish more mixing at stable
thermocline depths - generally in excess of 22 m.  Seiches may be  uni-
or  multinodal.   The  possibility  of  their presence makes a   single
temperature  observation  suspect;  observations  should be repeated at
each location  to  ascertain  conditions.   Observations off Chicago by
Project personnel in October 1961,  indicated 8-m vertical  movement of
an isotherm within 3 1/2 hours.  If such motion is typical, attempts to
estimate the volume of water available for mixing in the epilimnion (or
upper layer)  without a set of simultaneous  temperature-depth measure-
ments could be disastrously in error.

       It is  pertinent  to  insert  a discussion of  the Lake Michigan
temperature  structure here,  because temperature  structure determines
density structure, which in turn determines stability.  The most impor-
tant published  works are by Van Oosten (84),  describing data from 136
stations  occupied  from  mid-April  to mid-November in the years 1930,
1931,  and 1932;  by Church  (20),  describing  2,000  bathythermograph
soundings made between November 19^1 and February 19kk; by Ayers et al.,
(2),  describing four synoptic   studies of 50 or more temperature sta-
tions occupied in June and August 1958; and by Mortimer (5*0 giving the
first detailed  picture of temperature distribution in a  cross section
(his figure 6),  with a presentation of  evidence of inshore  upwelling
and wavelike  changes  in  temperature  provided  by  waterworks intake
records, and a prediction of the nature of the internal waves involved.

       During early winter months the Lake surface cools and convective
mixing occurs  as the denser colder  water sinks.   This mixing may not
affect the deeper areas of the Lake where water may already be at maxi-
mum density. At some time during this period the entire Lake will reach
a condition of  maximum density, about k°C.  At this time vertical con-
                                  19

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vective mixing ceases.   As the surface temperature  continues to drop,
the less dense colder water remains at the surface except for such mix-
ing as may result from wind or ware action.   Following the winter sea-
son, the temperature increases slowly until late spring, when the whole
Lake again  reaches  the temperature  of maximum density.   During this
latter period most of the Lake i» again convectively mixed.   Following
the spring period  when the Lake is  vertically isothermal  at tempera-
tures somewhat higher than k°C,  the surface temperatures will increase
rapidly  until  early  August,  by which time a very stable stratifica-
tion has  developed,  starting  with  the formation of a thermocline (a
layer  of rapid  temperature  decrease  3 to 15 m thick).   Thermocline
formation occurs first in the shallow inshore waters, and it is at this
time, when the central part of the Lake is isothermal at near ^°C, that
the  thermal  bar  described  by  Rodgers  (68)  may form.  Ultimately,
however,  the  result  of  spring  warming  is to produce a homogeneous
surface layer  over  the  whole  of  the Lake, with temperatures in the
region of 18° to 22°C separated by a thermocline (Church, 20 and Ayers,
2) from bottom water which maintains a temperature close to k°C. During
the time of intense stratification  (greater  temperature  differential
within the thermocline),  it is unlikely that even  the strongest winds
could cause complete vertical mixing;  only the water above the thermo-
cline (the epilimnion) is available for thorough mixing with pollutants.
Cooling of the epilimnion begins with September storms, and the thermo-
cline  weakens  as  the surface homogeneous layers cool and increase in
depth until the whole Lake becomes  isothermal at  about  4° to 5°C  in
December.

       According to Church (20),  minimum surface temperatures (between
0.5  and U.O°C)  are  reached  between  the middle and end of March, at
which time the main body of the  Lake is vertically isothermal.   These
temperatures are lower than  those  producing  maximum density; if such
low temperatures  could be found  in the deepest part of the Lake, then
their presence would conclusively  demonstrate complete vertical mixing
of the entire Lake volume for the year (Birge, 9).   (Church found them
in much shallower  water  on the  rise between Milwaukee, Wisconsin and
Muskegon, Michigan.)

       Dissolved oxygen (DO)  enters the  water  mainly from the atmos-
phere.  During periods of overturn the DO will tend to approach satura-
tion values,  but during periods of stratification  DO losses below the
thermocline  will not be  restored by  vertical mixing.   If pollutants
with sufficient Biochemical Oxygen Demand were introduced into or below
the thermocline, the DO concentration might drop rapidly to low levels.

       Two points  should be  emphasized.   First, the  volume of water
available for mixing keeps changing throughout the year, and it   is not
                                   20

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known whether the entire Lake volume mixes completely. Thus, at certain
seasons of a year, only the uppermost water (15 a) may be available for
diluting pollutants,  although events  near shore, where the pollutants
enter,  may often be complicated by the upwelling and downwelling phen-
omena described by Mortimer (54).   Second,  there  is a stable density
stratification for a significant portion of the year establishing three
zones,  each having  its own  temperature and density  characteristics.
Accordingly,  the  density  of  any  pollutant introduced into the Lake
determines whether the pollutant  would  stay  on the bottom, at inter-
mediate depths, or rise to the surface.

Advection

       Mixing as accomplished by turbulent motion  results from complex
random movements  involving relatively little transport of a water par-
cel, but changes in its Internal distribution. Advection is roughly the
opposite of turbulent mixing,  and refers to  linear movement  or gross
motion of a water parcel with mixing along its boundaries.  There are a
number of possible  situations between the two extremes,  random turbu-
lence and prevailing advection.

       Advection theory, in part, is in a more advanced state than tur-
bulence theory;  however,  a situation often is so  complex that  it is
exceedingly  difficult  to  obtain  even  semiquantitative predictions,
especially in the vicinity of shore lines (Hutchinson, U4).

       In Lake  Michigan  the wind  and pressure  fields seem to be the
chief causes of advection  (as well as internal turbulence,  previously
discussed).   Tides are negligible for most purposes, having a range of
some  1 cm  (Judson, Vf).   Seiches are important to  advection only in
restricted areas, such as  the Straits of Mackinac,  and perhaps in the
entry channels to Green Bay.  Precipitation minus evaporation, although
not known In definite detail,  is small enough to be  neglected in this
instance.  Because of the large area of transverse cross section of the
Lake,  net  flowthrough  produces  negligible  velocities of advection;
however,  flow in the Straits of Macklnac is often  reversed by seiches
and wind-tilt.   Church (20)  noted that during most of the year denser
water was  in the center of Lake Michigan  and less dense  water at the
edges, implying a slow counterclockwise density circulation superimpos-
ed on the net flowthrough.  Project personnel found a similar distribu-
tion off Chicago  in the fall of 1962.   A careful  review of  the data
indicates the presence  of more than one circulation pattern.   This is
supported by differences in earlier studies by Harrington (36), Johnson
(45), and the four synoptic cruises by Ayers (2).   According to Ayers,
major current changes caused by the  wind are often superimposed on the
more stable,  slower flow,  and changing winds are  responsible for the
varying currents observed.
                                  21

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       Balnea and Bryson (35)  find that the speed of a surface current
is 1.3 percent  of that  of the Kind producing it,  provided  the  wind
speed is less than 5-9 m/aec U3 »ph);  above this critical speed,  the
relationship is believed to be nonlinear.  Shulman and Bryson (72) find
the direction of surface  transport is about 20.6°  to the right of the
wind direction and that the  "depth of frlctional Influence" is between
1.8 and 3.3 •• These studies were conducted on Lake Nendota at Madison,
Wisconsin and may not be entirely applicable to Lake Michigan.

       In the discussion of thermal  structure it was pointed  out that
the thexmocline  separated the  homogeneous less-dense  epilimnion from
the denser homogeneous  bottom water.   Bryson and Bunge (15) find that
when the wind suddenly drops or shifts direction after set-up is estab-
lished, a rapid increase in current velocity is observed Just above the
thermocline.   They consider this current  to be the first  swing of an
internal seiche.   Accordingly,  significant currents may exist both at
the top  and bottom of the  epilimnion.   Lathbury, et al.,  (49) found
significant  currents below the thermocline also,  which they  consider
attributable not to seiches but  to thermally-and/or wind-induced pres-
sure gradients. Set-up causes a hydrodynamic pressure gradient, result-
ing in  currents along or  perpendicular to  the shore. Shoreline   and
bottom topography will also influence currents.   Because of the multi-
ple forces to be considered,  attempts to predict currents  soon become
complicated.

       Recent studies have shown that currents exist through the entire
vertical column of water.  Current velocities over 50 cm/sec at a depth
of 30 m were measured by the Project.

       On one occasion  Project personnel found  floating pollutants in
the vicinity of  Chicago's beaches and water intakes,  for several con-
secutive days  (USPHS, 82).   Generally speaking,  surface currents are
weak  and  southbound  near  Lake  Michigan's west shore, but narrower,
stronger,  and  northbound  near  its  east  shore.  Sometimes there is
evidence of a counterclockwise eddy in the Lake's southern basin. Again,
it is emphasized that these conditions are variable.

Meteorology

       The winds,  precipitation,  and  evaporation  over Lake Michigan
have rarely been measured.  One study "Report on Wind velocities at the
Lake Crib and at Chicago" by Hazen (37) (1883) was one of the few works
undertaken to determine  the wind differential  that exists between the
land and the lake.  Major Ira Bunt (It3)  U. S. Lake Survey,  working on
Lake Erie,  made some calculations on the wind differential that exists
over the Lake.   Applying the results of this study to Lake Michigan it
would appear that winds  over Lake  Michigan can be  96 percent greater
than those over the City of Chicago at certain times of the year.


                                     22

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       Data on evaporation and precipitation  over the Lake surface are
limited to estimates by the U.S. Lake Survey rather than precise obser-
vations. Radar studies of precipitation variations over the Great Lakes
are  still  in  the  experimental  stage  by both the United States and
Canadian Weather Bureaus.   Verber (87) reports that  convectional-type
rainfall over Lake  Erie is less  than at adjacent land stations.   The
U.S. Lake Survey embarked on a similar study in northern Lake Michigan,
and the results were reported by Bloust (ll).  Estimates on evaporation
have varied from 53 to more than 76 cm per year.  Estimates on precipi-
tation have also varied in the same range.   The U. S. Lake Survey (8l)
states that the average annual precipitation over Lake Michigan  (1900-
1960) is 77 cm.

Possible Fate of Pollutants

       The  following  factors  influence  the fate of an effluent dis-
charged into  Lake Michigan:  (a)  Existing current regime; (b)  Winds;
(c) Bottom topography; (d)  the Earth's  rotation; and (e) Density dif-
ference between pollutant and Lake water.

       If there is a current regime, it will  transport any  pollutants
introduced into it.  As previously noted,  there may be a counterclock-
wise gyre in the entire Lake or an eddy  in  the southern  portion that
would be the prevailing circulation feature.

       Wind-induced currents  can move Lake pollutants.   The wind cur-
rents may be superimposed on any  previously existing currents  and can
move in any direction.

       Topography may determine whether  a pollutant remains in an area
or not.  If the pollutant is less dense than Lake water, then it may be
moved by wind  currents  until  it is trapped against a shore.   If the
pollutant is  denser than Lake water,  it may run along  the bottom and
collect in depressions.

       If an effluent is discharged into  the  southern  basin  of Lake
Michigan and there is a density difference between the effluent and the
Lake water the following situations are possible:

       l)  If the effluent is low density,  it will rise to the surface
and under certain wind conditions may be carried along the southern and
western shores,  possibly affecting adversely water supplies that serve
populations  totaling  several  million  people as well as heavily used
bathing beaches.   Such conditions could last for many days.

       2)  If the effluent is soluble,  it may be kept in the  southern
end of the Lake by the eddy which is sometimes there. Under such condi-
                                   23

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tions,  concentrations of chemical constituents well in excess of those
normally present may build up.

        3)  If  the  effluent  i§  discharged at the bottom and has the
MUM density as the Lake water, there will be little vertical movement.
Under certain wind conditions it may  be carried by subsurface currents
to the Chicago water intakes or bathing beaches with little opportunity
for dispersion or dilution, or brought to the surface by upwelling.

       Each of the three  possible  situations cited above will be con-
siderably  more  serious  if  it follows a period of low wind and water
currents during which effluent concentration may build up in the vicin-
ity of diffusers. Such conditions may occur even when no ice is present
and,  on  the  basis  of  existing  wind  records, may be expected most
frequently during summer months.

        It)  If  the  effluent  is  of high density, it will sink to the
bottom and may run down to and collect in the southern basin.   Concen-
trations of various constituents  may build up and  seriously interfere
with existing aquatic life.   The  density  of  treated  effluent is so
close to that  of  the  Lake  water,  that, at different times of year,
temperature changes in the  Lake may result in the occurrence of any of
the possibilities listed above.

Previous Studies

       A detailed literature  search  disclosed three important studies
pertinent  to  the  measurement  of currents in Lake Michigan.  In  the
years from 1892 through  189^,  Mark  Harrington  of  the U. S. Weather
Bureau  released  over  1,500  drift bottles in the Lake, of which only
about 203 were recovered during the 3-year period (36).   These returns
formed the  basis  of the first  map of Lake Michigan surface currents.
In 195*1-55,  James  Johnson  of the U. 8. Bureau of Fisheries (45) com-
pleted an intensive  study  of surface currents using drift bottles and
drift envelopes.  Out of 6,26o releases, some 2,870 were recovered dur-
ing this study.  The study results indicated that during 195^ no stable
pattern  of  surface  currents existed.   In general, Johnson found the
drift was from west to  east  and  the north-south movements were about
equal.   A similar pattern existed in 1955 except that the drift in the
eastern areas was mainly to the north.  In 1958,  Ayers and others, (2)
published the results  of a series  of synoptic surveys,  in vhich they
applied a modification of  the dynamic height method and published  the
first map of Lake  Michigan  showing  subsurface  water  movement.  The
method, however,  is open to question because of the choice of boundary
conditions (Ayers, l).

       Townsend  (78), took sharp issue with Harrington on the method of
presentation of data.   He stated that in such a  confined area as Lake

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Michigan,  Harrington  could  not  assume curved line motion but should
have used straight line motion.   Townsend's ideas were partially veri-
fied by studies on Lake Erie  (Yerber, 85).

       It is difficult to translate drift card or bottle movements over
•aay days into  those of actual currents.   The only positive statement
that can be made about  drift methods is in reference  to the points of
release and retrieval.   9uch movements at best  can only demonstrate a
type of  pattern betveen the  times of release and recovery.   The seem-
ingly random  changes  betveen  Ayers1 and  Johnson's  work graphically
illustrate this point.  The more recent studies using bottles and cards
did not claim to show anything  other than the conditions  that existed
at that time and place.  Harrington,  however, tried to pin down speci-
fic current patterns from far less data over a  much greater time span.
The meters which  exist  today  were  unknown ten years ago and earlier
scientists could only use the tools then available.

       The dynamic height method of  obtaining  subsurface current data
has not been  substantiated by  means of current meters.   Criticism of
the method is based on two assumptions.  One, the method assumes a zero
velocity depth level which may or may not be correct.   Two, the theory
assumes constancy in the isothermal  lines over a short period of time,
whereas it is  known  that  internal  waves  may  produce very striking
thermal changes in lakes and  also in the ocean (Verber, 86).

       Since none of the past studies showed net circulation,  maximum
current speeds,  effects of storms,  or detailed  Inshore  circulation,
further work was necessary to give the answers needed today.

Procedures

       Procedures  for  the   study  are  a  combination  of old and new
techniques.   These  have  been  selected  through   consultation  with
oceanographers of the Chesapeake Bay Institute, Harvard University, and
Mew York University.

       The study period on the  Lake involved approximately l£ years of
data collection.   The review of past studies,  experimental testing of
equipment,  purchase of equipment,  and the  development of  techniques
preceded the actual study and required nearly 18 months.

       To provide  quality  control  of the data, services were secured
from other agencies.   The Project established cooperative arrangements
with the Rational  Oceanographic Instrumentation Center for basic cali-
bration of the instrumentation.   Aircraft and  photographic techniques
used in the study  of  littoral  currents were provided by personnel of
the  U. S. laval Air Station  at Olenview, Illinois.   The precision of
navigation was  accomplished  through utilization of vessels and person-
nel of the U. 8. Corps of Sagineers and private facilities.

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                         Temperature Studies

       Temperature  studies  on  Lake Michigan were made from September
1961 to 19&1.  Approximately 20  cruises  were  made on the Lake during
this period, vith more than 1,300 bathythermograph casts.   Information
gained  during  these studies was used to establish the various config-
urations  of  the  thermocline during spring, summer, fall, and winter.
Temperature information gained  throughout  the year was used to deter-
mine the depth of mixing  and  variations  in density layers within the
Lake.

       In addition to securing data from bathythermographs  the Project
secured 200 temperature recorders, designed by Woods Hole Oceanographic
Institute, which  were  used  in conjunction with the current meters to
determine the location of  the  thermocline  and  magnitude of internal
waves.

                            Tracer Methods

       Drogues were used for inshore studies.  The drogues consisted of
a cloth or metal vane suspended  in the water at the desired depth by a
line attached  to a small surface float.  The cross section of the vane
is sufficiently large to make the movement of the assembly dependent on
forces  acting  directly  upon  the  vane, with negligible effects from
forces acting on the line and surface float.  The movement of the  vane
below the water surface  is  followed by  corresponding movement of the
surface float.   Several drogue studies, using both  a  small boat  and
aerial photography, were conducted in the Chicago area during the study
period.   The  first  drogue  studies  made by the Project were used to
develop techniques and methods of study.   Drogues  were  used to study
current patterns and mixing in shallow water.

                   Fixed-Position Current Metering

       Of the available techniques for  the investigation  of currents,
the use of fixed stations with automatic recording meters was  selected
as most applicable  for studies of  mass water  movements  in the Great
Lakes.

       Three types  of measuring  systems  were considered seriously by
the PWPCA:  The Woods Hole  Oceanographic Institution  meter, developed
by Dr. William S. Richardson (65), a telemetry  system devised in  1962
by the U. S. Corps of Engineers (80),  for the Public  Health  Service;
and a modular system, Frantz (33), devised by Marine Advisers, Inc. The
first is  completely  self-contained  and  has an automatic  mechanical
system for recording data on 16 mm photographic film. The other two are
dependent upon an external  unit to supply  power and record data elec-
tronically.  All have many desirable features  not found in other types
of current meters, such as:
                                   26

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        l)  The ability to  Measure  low current speeds,  down to about
1.0  cm  (0.03 feet) per second by utilizing a Savonius rotor.

        2)  The ability to operate untended for up to four months while
recording observations hourly.

        3)  The ability to measure direction ± 7°.

        k)  The  ability  to  record  observations at shorter intervals
than one hour.

       Each meter  has particular  characteristics which make it desir-
able for use under  certain conditions.  After a careful review of  the
three meter  systems as they  related to study requirements,  the Woods
Hole meter was selected as the most suitable for anticipated field con-
ditions .

       After the method of study was selected and testing of meters was
underway,  plans were developed for selecting the number of stations to
be instrumented, their location, instrument servicing, and the process-
ing  of data.   The selection of stations and  the number  of meters per
station were subjects of a  conference held in Chicago  with scientists
from the Great Lakes States and Canada.  It was decided that the stand-
ard  procedure  of equal  area and  depth coverage  was the most logical
method.   To study all of Lake Michigan  it was agreed  that between 30
and  to stations should be set.   The number of meters to be set posed a
problem because of the variability of the thermocllne.   It was readily
agreed that the  meters  should be set  at fixed depths,  and at closer
spacing in the upper layers.   The depths  selected were:   10, 15, 22,
30 m and each succeeding  30-m level.   No meter was set less than 10 m
below the surface because of problems resulting from surface waves.

       The preliminary recording of data  was different for the various
types of meters.  The  telemetering  station  recordered  hourly on its
internal  recording  system and  transmitted the  data every k hours by
radio to a  receiving station.   The  telemetry  system  reported total
revolutions of the Savonius rotor in each k-hour interval together with
one  instantaneous direction reading made at the time of reporting.  The
Woods Hole meter  at different times was used on a continuous recording
mode and then on a mode recording 50 seconds continuously once every 20
minutes. The recording for the full-scale study was set at a continuous
50-second recording  period once each 30 minutes for the winter months,
but  intervals  were reduced to 20 minutes for the rest of the year. The
longer period  was adopted  for winter operation to provide a margin of
safety against  exhaustion  of the  power supply  batteries Inside each
unit.   During severe winter  weather  it was impractical  to visit the
stations for retrieving data, replacing batteries, and other servicing.
Approximately 200 Woods Hole current meters were used in the study.
                                   27

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                          Equipment Testing

       Many of the  theoretical  concepts  of water  movements  in  the
oceans and  the Great Lakes hare defied testing  because of the lack of
adequate instrumentation.   With  the  advent of the Savonlus rotor and
the development of the Woods  Hole meter  a valuable  new tool was made
available  to  the  scientist.   An  equally  important development aad
essential to the mass use  of the meter  was the perfection of an auto-
matic readout system in July 1962.   Reading speed and  direction every
20 minutes,  each of the 200 meters would record 52,560  observations a
year.   The manual reading of this information directly from film would
have been prohibitive in cost.

Description of Test Studies

       The study of currents  in Lake Michigan  by using current meters
began October 21, 196l  with the setting  of an experimental  telemetry
station.   The station was first  set about  to km northeast of Chicago
(Figure 3-1), but was removed after three days because of a defect.  It
was reset on May 15, 1962 about 2k km northeast of Chicago. From May 15
through November 1, 1962,  several different  types of station were set
for the purpose of  evaluating meter performance,  mooring systems, and
other features of the  instrumentation,  preliminary to the  full scale
study.

                       Results of Test Studies

       This section will describe the results of  the observations with
respect to the following factors:

        l)  The reliability and sensitivity of instruments  under field
conditions.

        2)  Mooring characteristics.

        3)  The operating characteristics of different types of current
meter installations.

        4)  Flow characteristics.

        5)  The relationships between winds-on-shore and lake currents.

        6)  Correlation between meters at one station.

       The results of the tests are shown on a series of graphs.  These
graphs present results of  statistical tests  on the data obtained from
the current meters.  Speed readings are given in centimeters per second.
                                    28

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WISCONSIN
 ILLMOiS
                                                   Subsurface Currant Station
                                                        October, 1961
  0 I Z 3 4

 SCALE M MILES
 Subcurface
Current Station
 May, 1962
     O
                                            GREAT  LAKES  -  ILLINOIS
                                              RIVER  BASINS  PROJECT
                                            CURRENT METER STATIONS
                                            U.S DEPARTMENT OF THE INTERIOR
                                        FEDERAL WATER POLLUTION CONTROL ADMIN
                                        Great Lakes Region           Chicago,Illinois
                                                               FIGURE  3-1

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Direction readings  are given la ten*  of degrees  clockwise from mag-
netic north. The readings for direction given in this section represent
the direction from vhich the current is coming.

       Figures 3-2 and 3-6  vere examined for  correlation and equality
in direction.   If the absolute value of the  median  difference of the
readings between two meters is  significantly less than  90° a positive
correlation exists.

Reliability

       The reliability and sensitivity of the meters vere determined by
an examination of results, i.e.,  speed and direction data, rather than
by an analysis of the physical characteristics of the meters.   A study
of the data alone will  not disclose systematic  errors in the measure-
ments;  however,  such errors are  believed  to be small, based on tank
tests in which the sensors were towed through still water.

       The data used for reliability  evaluation were from two separate
stations - the telemetry station with three meters, set at 18, 27,  and
36 m, and a station with one meter of the  Woods Hole type set at 40 m.
The two stations were within 90 m of each other. The recording interval
for the telemetry station was  once every four hours with some observa-
tions at 10-minute intervals.  The total time of recording was 63 days.
The Woods Hole meter recorded  continuously  and  the data were printed
out at 1.25-minute intervals.   The record length  for  this meter  was
6 days, July 5 to 10, 1962.

       Figure 3-4 shows a series of current meter readings taken during
a period of increasing flow.  The data show two types of changes in the
speed, a long-period systematic rise  and a short-term  random fluctua-
tion.   The long-period rise shows  an increasing  current  speed.  The
short-term random  fluctuation could  be due to changes  in the current
speed or to  instrumental error.   At this  time it  is not possible to
distinguish between  the two changes and they are grouped  together and
treated as physical measurement limitations.   The amount of the random
fluctuations is  used to estimate the precision  (repeatability or con-
sistency) of the data.

       The problem of  variation  measurement is  to measure the short-
term changes without including the long-term systematic variation.  The
simplest  solution  to  this  problem  is  to assume that the long-term
systematic variation is approximately zero over a short period of time.
Thus,  over a short period of time,  the total variation can be used to
approximate the random fluctuation.

       Under steady-state conditions,  the larger the quantity of  data
collected,  the more accurately it will  represent the data of which it

-------
is  a  eao^le.   However,  the  larger  the  quantity of data used, the
greater the time span.  Thus, the problem is to use a large quantity of
data without spanning a long period of tine.   The solution is to  have
as short a period of time between observations as possible.

       The data in Figure 3-V fro*  the Woods Hole aster  were  plotted
from the readings made at 5-minute intervals.   The figure is a plot of
•agnitude (speed) against tioe.   The plot represents a 12-hour portion
of a 40-hour period and indicates that  the meter is capable of detect-
ing long-term  systematic  changes  in  speed.   However, initial tests
showed a large random variation in  direction at higher speeds,  due to
the type of mooring system used.

Mooring Characteristics

       The original mooring system used by Dr. Richardson of Woods Hole
in the Atlantic  Ocean  was  modified  for  use  in Lake Michigan.  The
Atlantic installation  used a synthetic line anchored to the bottom and
held at the surface by a large float.  Ice and severe winter conditions
prevented the use of a slack wire mooring system in Lake Michigan.  The
Project  used  a  taut  wire system with a subsurface float which has a
positive buoyancy of 250 kilograms.   A surface float,  for use in ice-
free periods, was attached by a slack line to the subsurface float.  An
examination of the original test data showed  unusual variations in the
direction vane.   Observation  disclosed that during windy periods  the
large surface float  was capable of  jerking the lower taut line in any
direction.   To  prevent  this  action  and  the consequent swinging of
direction vanes on the meters, the mooring system was changed to a two-
line system.   This  present  system  leaves the meter line almost com-
pletely free from external stress.

Operational Characteristics

       The mooring  system  used  at  the telemetry station had a small
surface float relative to the subsurface float.  Therefore, the pull of
the surface  float did not  affect  the direction  vane on the sensors.
Thus, the data from the telemetry station  were used in the analysis of
direction reliability.   The 10-minute time intervals were used for the
analysis.  Figure 3-2 shows confidence limits using 10-minute intervals
(Dixon, 27, p. 294).  The results in Figures 3-3 to 3-6 show  acceptable
precision in both  magnitude and  direction at each  of the depths (18,
27 and 36 m).

       The Savonius rotor has  been  tested to determine  its degree of
reliability, response  in  turbulent motion,  and  dependability   over
periods of time.   The rotor, as used, is sensitive to about 0.9 cm/sec
as shown by tow  tank tests conducted by the Corps of Engineers.   Test
by Gaul (3*0 indicates  that the rotor is very reliable between 0.8 and
212 cm/sec.


                                  31

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  35
                                            FIGURE   3-5

-------
FIGURE 3-6

-------
       The rotor  10  omnidirectional,  which means that it will  sense
action from any direction in a  horizontal plane when set with its axis
of rotation  vertical.   The orbital  Motion of waves  produces a surge
forward  and  then  backward  as  it passes.  This effect on a Savonius
rotor would show as an increased  speed.   Wave action,  during  severe
weather conditions, can be detected as deep as 15 m.   For this reason,
the uppermost  current  meter  is  at  the  10-m level and will only be
affected during the more adverse conditions. Figure 3-8 shows a typical
rating curve for the rotor made by the Corps of Engineers.

Flow Characteristics

       A preliminary examination was made of the flow data. The follow-
ing were investigated:   relationship between  wind and water movement,
relationship  between  readings  at  different  stations,  relationship
between readings  at different  levels, range  of speeds,  and possible
predominant directions at different speeds.

       Iftich of the report depends  on statistical testing for relation-
ships  or  correlations  between  two  variables.   A  positive  result
(correlation)  implies  95-percent  confidence  that a  relationship or
correlation does exist.  A negative result (no correlation) Implies one
of the following  two  possibilities:   either  no  relationship exists
between the variables  in question or a relationship does exist but the
nature of the statistical test or the  data was such that the relation-
ship could not be detected.

       Two limitations on  the  applicability  of  the findings in this
report should be mentioned.   The current meter data  represent samples
from a changing physical system.  Thus, physical relationships which may
occur for one period  of  time  may not necessarily occur for any other
period  of  time.  For example, it is possible that systematic seasonal
differences  are  not  reflected in the  tests reported herein.   Also,
the relations which are here established represent average effects. The
only thing necessary to produce  a  nonrandom  effect  during the whole
period of time is a large  enough nonrandom effect  to balance out this
effect on the overall result.  The conclusion that can be obtained from
a positive  result is that one can expect  (with 95 percent confidence)
that the result held more than  50 percent of the time,  for the period
of study (Dixon, 27, p. 280).

Winds and Currents

       An attempt was made to correlate wind and  current  data.   Wind
data  were  estimated  (from shore based stations)  for the  10-m level
(above the lake surface) and the current data were taken at 20 m  below
the surface.  Various relationships were tried, using a variety of ways
                                   37

-------
of weighing past wind averages  and correlating with  present currents.
Bo positive correlation could be found.  This does not necessarily mean
that wind does not affect  water currents.   There is  every  reason to
assume that such relationship exists, but detection is difficult at the
greater depths.

Correlation Between Meters at one Station

       A test was made to correlate  currents at different  depths (l8,
27, and 36 m) at the same station.  Both magnitude and direction showed
positive correlation  at 95 percent confidence.   Figure 3-3  shows the
magnitude (speed) relationship at 18 and 27 m. The positive correlation
can easily be seen.   It can also be seen  that the speeds at  18 m are
greater than speeds at 27 m on the average  (a difference in medians at
95 percent confidence is shown).   Speeds at the 35-m depth were gener-
ally  lower  than  the  minimum detectable speeds on the current meter.
Figures 3-5 and 3-6 compare  directions at different depths.  The  mean
direction of current, for the whole period at 30 m, was to the right of
that at 20 m, whereas the mean at kO m appeared slightly to the left of
that at 30 m,  with 95  percent  confidence.   While the first   result
might be considered as consistent with Bkman transport (75), the second
result  is  zero.   As  far  as  they  go,  these results confirm that,
because of  shallow  depth and seasonal stratification, fully developed
Ekman spiral flow will rarely be encountered in Lake Michigan.

       Figure 3-7 is a histogram which is designed to show the range of
speeds  at different depths.   The abscissa is a group  of speed ranges
and the ordinate is the percent of time that the readings fall into the
range specified in the abscissa.   There are  differences in  speeds at
different depths, and the greater speeds are the bars which are farther
to the right.

       Figures 3-9 and 3-10,  show polar  coordinate  diagrams of speed
and direction at two of the depths observed. Table 3-1 shows the number
and percent of  observations in  each quadrant,  the average  angle and
speed for each quadrant,  and the maximum  number of  times the current
was found in a  specific quadrant.   The number of  times the  readings
were in the northwest quadrant was unusually high, indicating a 95 per-
cent probability nonrandom effect  (Tate, 76, p. 35).  One meter showed
northwest currents over four days in succession, Table 3-1.

       The results of these  preliminary tests  in one area of the Lake
may be summarized as follows.   The two current meters in the same area
showed,  on the average,  correlation in direction and general correla-
tion in speed  and direction at  different depths.   In general,  speed
decreased with depth,  and  average  shifts  In  direction at different

-------
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                ixr
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       dinette* m«OM**tf «t «n4 *f
       riwL
       Itoy t«, lf«t-Jw»y 2«, IMt

 X Average velocity for quadrant
    GREAT  LAKES  -  ILLINOIS
     RIVER  BASINS  PROJECT
POLAR DIAGRAM OF MAGNITUDE
    AND DIRECTION AT  18 M.
                                             U.S.DEPARTMENT OF THE INTERIOR
                                         FEDERAL WATER POLLUTION CONTROL ADMIN
                                         Great Lakes Region           Chicago,Illinois
                                                                   FIGURE 3-9

-------
      MO*
300*
                                                                                  I20»
                    210°
   NOTE:
                  *v«r t«ur hour*. (Mton-
                    «o«ur*4 at «n4 «f
     ••eh »«flpd.
     ParM: htay <«, IM2-July 26, IMf.
     The three points located outside the graph
     limits ore; 310°, 24Cms.288°, 23 Cms.
     ond 252°, 19 Cms.
     X  Average  velocity tor quadrant
L
                                                     GREAT  LAKES  —  ILLINOIS
                                                       RIVER  BASINS  PROJECT
                                                POLAR DIAGRAM OF MAGNITUDE AND
                                                      DIRECTION AT  27  M.
                                                   I'S.DEPARTMENT OF THE INTERIOR
                                               FEDERAL  WATER POLLUTION CONTROL ADMIN
                                               Great  Lakes Region           Chicago.lllmois
                                                                                  " 10

-------
                               CABLE

                Current Meter Beading* in Each Quadrant*
                         Meter 1 - 18 M Deep
 Quadrant

   0-90°
  90-180°
 180-270°
 270-360°
Consecutive
Beading* in
Quadrant

      k
      3
      3
     20
                                  Observation
   0-90°
 90-180°
 180-270°
 270-360°
   0-90°
  90-180°
 180-270°
 270-360°
      9

     26
      3
      6
      3
     13

Humber
62
33
58
102

jrereent
Of TiBB
2*. 3
12.9
22.8
JtO.O
                                         100.0
                          Meter 2 - 27 M Deep
 77
 59
 60
10*
25.6
19-7
20.0
                                         100.0
                          Meter 3 - 36 M Deep
 66
 63
 73
 98
       Average**
Magnitude
CM/SEC

  5.6
  5.8
  6.6
  6.8
  5-3
  k.k
  5.6
  7.7
  0.5*
  0.012
  0.015
  0.33
Direction
Degrees
  139
  228
  310
  131
  228
  316
   38
  138
  223
                                         100.0
 *Beadings are approximately four hours apart.
**Arithmetie average of magnitude and direction.

-------
depth* were  detected.  For instance,  the MM  current  direction  at
27 » ley to the right of that at 18 a.  The  currents at 36 m  appeared
to the left of those at 27 •.  As Motioned earlier, the current speeds
at to • were frequently belov the minimum  threshold capability of  the
rotor. It is probable that the vane response to movement was also close
to its minimum range of  detection.   The speed ranges are shown on the
histogram plotted. The polar coordinate diagrams and Table 3-1 indicate
a predominance of currents from the northwest during the period sampled.

Significance of Findings

       The data shov that an effluent discharged into the Lake,  at any
depth, can nave a prevailing direction of movement.   During the period
of Nay to July 1962,  this movement at  the test station would normally
have been from the northwest at the three levels observed.  The n^rlimm
consecutive readings from the  northwest varied from three to more than
four days with an average drift of seven or more kilometers per day for
the Id- and 27-*eter levels.  The rate of flow is expected to be higher
in the upper layers.

       Although  mixing  occurs  during  severe  weather conditions the
exact rate or amount are unknown.   Earlier studies  when  the  Chicago
River was diverted into the Lake in September 1961, show  that the dis-
charged waters maintained a detectable  eoliform count for 5 days, (fit).
Therefore, it may be possible that even  during periods of high veloci-
ties  for  8  or  more  hours  the  effluent will not be mixed into the
surrounding water.

       The worst condition  appears  to be when  an effluent remains in
the general  vicinity  of its  discharge point because of extremely low
velocities.   After a period of building-up,  the concentrated effluent
might then be moved, en masse, by the current. Relatively slow currents
could move the effluent for  k or more days in one direction,  as shown
in Table 3-1,  or a fast  moving current could produce  the same result
within 5 to 8 hours.

       This is the first  occasion  on  which  current meters have been
operated for  continuous  periods  in Lake  Michigan and, although they
demonstrate average trends, they also show a far greater variability of
flow than that indicated by previous studies.

Summary of Test Studies

       The data and performance tests from the first meters set in Lake
Michigan were examined and evaluated.   The tests were made to evaluate
the type of  meters  to  be  used  and  reliability of the instruments'
internal components.   The test  data were  examined for persistency of
movement and the variations of speed with depth.


                                   kk

-------
       The data tabulated for May to July 1962, ahow that radar certain
conditions an effluent could move,  at low spaed with relatively littla
mixing, for over k days.  Movement during other periods of tha year amy
•how that there are other  quadraata in  which the eorreat will predom-
iaate for longer perioda of time.

       Taa teat data indicated that the  reliability and eeaaitivity of
all Mtera for •eaauriag both apeed and direction were satisfactory for
study purposes. The data froa the iaatruaanta using one type of noorlng
•ysten indicated that the large surface float had an effect on the vane
direction.  An alternate  mooring system was devised  to eliminate this
possible source of error.

       Three types of meter systems were  evaluated and the  Woods Hole
meter waa selected because of the eatabliahed performance record of ita
internal components, type of data collected, and lower coat.

-------
                              CHAPTER k

        METHODS FCR MOGRIMGS, IHSTRUMSR CHECKS, FILM FROCESSIHG
                         AMD FUJI CCRVKRSIQV
Introduction

       To successfully complete the largest current study ever planned,
new methods and technique*  had to be  devised  to insure  reliability,
efficiency, and standardization.

       The Instrumentation  used was  designed and  tested at the Woods
Hole  Oceanographic  Institution.  Since these  instruments were  rela-
tively new, they have undergone BOOK modification with time.

       An Instrument shop was  established at each  field station where
operations were being conducted. An instrument technician and assistant
were in charge of all repairs, loading and unloading film, and calibra-
tion systc
       Prior to each station installation,  the instruments are given a
complete mechanical check. This checking includes the following instru-
ments:  current meters, temperature recorders, anemometers, lights, and
recovery buoys.

       In setting a station,  a form is  filled out shoving all Instru-
ment serial  numbers,  line lengths, etc.  A sample diagram is shown In
Figure 4-1.

Mooring Systems

       The meter mooring system  used  by  the  Federal Water Pollution
Control Administration  in the Great Lakes has been basically standard-
ized with minor modifications as the program progressed.

       The system used  during  the  ice-free season is shown in Figure
4-2.   The  current  meters,  each  paired  with  a  water  temperature
recorder, were suspended in a  taut line between a subsurface  buoy and
anchor.  A slack line connected  this  anchor  to another nearby anchor
which moored,  on  a  slack line, a surface buoy.  The surface buoy was
instrumented with a water temperature recorder,  a wind recorder, and a
navigation light. Ordinarily, a small surface float was attached to the
subsurface  buoy by a 0.6-cm (£") slack manila line, and a staff marker
buoy was set separately  but  nearby.   These  markers were set to help
assure station recovery.

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     GREAT  LAKES  -  ILLINOIS
      RIVER  BASINS  PROJECT
        STATION  DIAGRAM
             SUMMER
   U S DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL AOMIN
Great Lukes Region           Chicago,Illinois
                         FIGURE  4-1

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FIGURE 4-2

-------
       Winter metering  station*  were  similar except the instrumented
surface buoy was replaced by a subsurface recovery  buoy set to surface
in the spring by  use of a clock-controlled  actuator  (Figures 4-3 and
4-4).  A second recovery  buoy vas attached to the main subsurface buoy
to help assure recovery, Figure 4-5»

       In detail,  a Metering station consisted of the  following array
beginning with the subsurface support buoy  (Figure 4-6).   The  top of
the subsurface buoy  was approximately 7.2 «  below  the water surface.
A temperature recorder  (Figure 4-7) vas attached to the  bottom of the
subsurface  buoy  with a 1.2-cm shackle.   The temperature recorder vas
attached to a current meter (Figure 4-8).  At the bottom of the current
meter vas shackled a 1.2-cm  (£") by  12.5-cm  (5") ring.  The ring, in
turn, vas shackled to a thimbled,  1.6-cm  (5/8") braided polypropylene
line,  3.3 »  long.   At  the  bottom of the 1.9-cm (3A") line another
temperature recorder vas shackled and the sequence repeated.   In  this
manner,  current meter-temperature recorder pairs  were set at approxi-
mate depths of 10, 15, 22, and 30 m and every 30 m thereafter,  depend-
ing upon total water depth.

       The bottom of the  instrument  line  vas attached by a length of
1.0-cm (3/8") chain and shackles to a 362-kg railroad car  wheel anchor
(Figure 4-9).

       Another short  length  of  chain  vas shackled to the instrument
anchor.  Polypropylene 1.9-cm (3A") rope vas shackled to the chain and
leads across the bottom to a second wheel anchor at a distance equal to
or exceeding l£ times the water depth.   The rope vas again attached to
the second anchor by  a short length of chain.  At the  juncture of the
rope and chain vas a 1.6-cm (5/8")  by 12.6-cm (5")  steel ring (Figure
4-10).  To this ring the instrumented surface buoy vas moored by 1.9-cm
(3/4") polypropylene rope.   This rope vas slack and leads  up to a 6-m
length of 1.0-cm  (3/8") chain, which in  turn was shackled to the buoy
bridle.  After some difficulty vas experienced  in pulling this anchor,
a weak link of 1.2-cm (£")  polypropylene rope vas  put into the system
between the anchor chain and ring.

       A temperature  recorder  vas  installed  in  the  bridle  of the
surface  buoy  (Figure 4-11).  A navigation  light  (Figure 4-12)   vas
mounted on the top platform of the buoy tower.  A wind recorder (Figure
4-13) vas  Mounted  on  the  lover  platform.   Its velocity sensor vas
mounted atop a pipe about 6l cm (2f) above  the top of the  buoy tower,
3.6 m above the water surface  (Figure 4-14).   The surface  and  other
buoys are shown in Figures 4-15 and 4-l6.

       The entire station array is  assembled on  deck prior to launch-
Ing.  The subsurface buoy and attached Instrument group are put  in the
                                   49

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RECOVERY
INSTRUMENT
LATCH PIN

RELEASE RING

1/2" SHACKLE



CHAIN
                                      FLA& MARKER
                                      ALUMINUM POLE
                                             SCALE


                                         0           4 IN.
                                         I J I I I    I   I   I
                                         I  I  Tl  I   I
                                         0           10 CM.
                                      FIBERGLASS FLOAT
                                      (DAY-GLO FIRE ORANGE)
                                                                     84
                                24"
                                                                      12
LINE STORAGE CASE
                                      HOSE CLAMP (5 REQ'D.)
                                24


RUBBER DIAPHRAGM
WITH SLIT

7/16"  BRAIDED
DACRON-NYLON LINE
THIMBLES
GALVANIZED STEEL
LIFTING EYE

FIBERGLASS
SUB SURFACE BUOY
(DAY-GLO FIRE ORANGE)

    MATERIAL

    STAINLESS STEEL OR ANODIZED, EPOXY-
    PAINTED ALUMINUM.
                30  DIA.
                                               GREAT  LAKES -  ILLINOIS
                                                 RIVER  BASINS  PROJECT
                                               RECOVERY  BUOY  SYSTEM

                                                       NOT TO SCALE
                                              us oenurrMCNT or TMC NrrcmoR
                                                   WWe* POLLUTION CONTROL A WHIN.
                              50
                              FIGURE 4 - 3

-------
LINK
MATERIAL
STAINLESS STEEL
                     TOP VIEW
MATERIAL

POLYVINYLCHLORIDE

FINISH

YELLOW  EPOXY PAINT
 THIS END TO RECOVERY
 INSTRUMENT  	
                                  SECTION  A-A
 THIS END TO LINK

7/16"  BRAIDED
DACRON-NYLON  LINE
                                                                 LINE STORAGE CASE

                                                                 NOT TO SCALE
                                                    GREAT  LAKES  -  ILLINOIS
                                                     RIVER  BASINS  PROJECT
                                                 LINK 8 LINE STORAGE CASE
                                                  U.S Of WWRTKtfNT Of TH£ INTERIOR
                                                       MUTER POLLUTION CONTROL AOMIN
                                                                       Chlcogo,iil»n
-------
•>
E
a.
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a
        10-
        15-
        22-
        30-
                 —Recovery buoy

                  -Sub-surface  float
                                            Recovery  buoy	
                   Temperature recorders-Woods Hole type
 Current  meters-Woods Hoi* type



6 cm. braided  poly line

          pairs at each succeeding 30 meter level
                       1.9 cm. mono-polypropylene rope	
              >0.95 cm. BBS chain  \,          concrete anchor
               /  wheel  anchor       \^             136 kg.
                  386 kg.
                                                          NOT TO SCALE
                                                   GREAT  LAKES  -  ILLINOIS
                                                    RIVER  BASINS PROJECT
                                                 TYPICAL CURRENT STATION
                                                            WINTER
                                                 U.S DEPA*m*ENT OF THE INTERtOH
                                              FEDERAL KATER POL LUTK5N CONTROL AOMIN.
                                              Qrtot Lakti Region           Chlcaqo.ttlifioU
                                                                             4-5

-------
 FIBERGLASS
 WRAPPED
                                                  GALVANIZED STEEL
                                                  LIFTING EYE
                                                                 a" O.D. X 1-3/4" l.D.
                                                                 ALUMINUM TUBE

                                                                 LENGTH - 25"
MATERIAL
FIBERGLASS

FINISH
DAY-GLO FIRE ORANGE
     SCALE
 0      5     IOIN.
 MINI,  .
SECTION A-A
 0
             25CM.
                        GREAT  LAKES  -  ILLINOIS
                          RIVER  BASINS  PROJECT
                                                    SUB  SURFACE  BUOY
                       U S OEPAWTM€NT Of THE INTERIOR
                   FEDERAL WATER POLLUTION CONTROL AOMIN
                   Sreot Lakes Region           Chicago,Illinois
                                                                      FIGURE 4-6

-------
     CAM ADJUSTMENT KNOB
     (BACK SIDE}
     PEN ARM

     PEN PRESSURE ADJUSTMENT


     PEN LIFTER
     TEMPERATURE SENSING
     BULB
MATERIAL
ALUMINUM S STAINLESS STEEL

FINISH
OXIDE FINISH 8 YELLOW EPOXY PAINT
ON ALUMINUM PARTS
                                                      LIFTING PAD
                                                      (MAY BE USED ON BOTH ENDS)
                                                      PRESSURE CASE (ALUMINUM)
       RECORDER SWITCH
       CONTINUOUS OFF INTERVAL
                                                      SPINE


                                                      MOTOR CAM a SWITCH
                                                      RELEASE CATCH FOR SPOOL
                                                      SHAFTS
       WAX-PLASTIC CHART PAPER


       SUPPLY ROLL


       TEMPERATURE ELEMENT


       HIGH-LOW TEMPERATURE STOP





       BASE CAP
                                                          SCALE
                                                       III
                                                                  4IN.
                                                                  IOCM.
 GREAT LAKES  -  ILLINOIS
   RIVER BASINS  PROJECT
TEMPERATURE  RECORDER
                                               US,DEPARTMENT OF THC INTERIOR
                                           FEDCRAL WftTER POLLUTION CONTROL ADMtN
                                                                    FIGURE 4-7

-------
MATERIAL
ALUMINUM 8 STAINLESS STEEL

FINISH
OXIDE FINISH 8 YELLOW EPOXY PAINT
ON ALUMINUM PARTS
                                                       LIFTING EYE
                                                       VANE
                                                       VANE FOLLOWER

                                                       CAMERA

                                                       PRESSURE CASE (ALUMINUM)
                                                       FIELD OF VIEW

                                                       TIMING CLOCK

                                                       COMPASS
                                                       BATTERY
                                                       TIE RODS (3)
                                                       ROTOR FOLLOWER
                                                       SAVONIUS ROTOR
                                                            SCALE
                                                        0      5     IOIN.
                                                            Ill      I
                                                                    25 CM.
GREAT  LAKES  -  ILLINOIS
 RIVER BASINS  PROJECT
    CURRENT METER
     WOODS HOLE TYPE
                                                US DEPARTMENT OF THE INTERIOR
                                             FEDERAL WATER POL LUTtON CONTROL ADMIN.
                                             Gr«at Lok«« fttgion           Chtcogo.lllmaU
                               55
                    FIGURE 4-8

-------
                                           STEEL ROD EMBEDDED IN CONCRETE
                                25 GAL. DRUM
                                FILLED WITH
                                CONCRETE
                                (94.7 liters)
STEEL ROD WELDED  TO AXLE
AXLE
STEEL FREIGHT
CAR WHEEL
              -H-
-H-
 i i
         850 LB. WHEEL ANCHOR

         (362 Kg.)
  MATERIAL
  AS SHOWN
                                225 LB. DRUM ANCHOR

                                (I 0 0 K g .)
                               GREAT  LAKES  8  ILLINOIS
                                 RIVER  BASINS  PROJECT
                                                        ANCHORS

                                                          NOT TO SCALE
                                                  US DCPMtTMENT OF THE INTERIOR
                                                      »|»TERPOL LOTION CONTROL AOHWN
                                                                       FIGURE  4 -9

-------
         FRONT VIEW
MATERIAL
GALVANIZED STEEL
                        5/8" POLYPROPYLENE
                        LINE
                        THIMBLE
                        1/2" SHACKLE

                        1/2" X 4" RING
                                                 SIDE VIEW
                                                           SCALE
                                                                   4IN.
                                                            I   I  T
                                                                   IOCM.
                                                 GREAT  LAKES  -  ILLINOIS
                                                  RIVER  BASINS  PROJECT
INSTRUMENT  LINE COMPONENTS

           NOT TO SCALE
                                                U S DEPARTMENT OF THE INTERIOR
                                            FEDERAL WATER POLLUTION CONTROL ADMIN
                                                 Lakes Rtgion           Chicago,Illinois
                               5T
                                                                     FK3URE 4-10

-------
  GALVANIZED STEEL
  EYE
                  5/8" X 4" GALVANIZED
                  STEEL RING
   SCALE
 11 i I   I    l
            4IN.
GALVANIZED STEEL
JAW
            10 CM
MATERIAL
STAINLESS STEEL
                          GREAT  LAKES  -  ILLINOIS
                           RIVER  BASINS  PROJECT
                                                         RIGID  BRIDLE
                                                          NOT TO SCALE
                                                 U.S DEPARTMENT OF THE INTERIOR
                                              FEDERAL WATER POLLUTION CONTROL ADMIN
                                              Grtat Lukes Region           Chicago,Illinois
                                                                        FK5URE 4-11

-------
                                                   GLASS LENS
22
                                                         ALUMINUM WITH BAKED ENAMEL
                                                         FINISH
                                                                    STAINLESS STEEL
   7/16" DIA. 6 HOLES

   60° APART ON A

   9-l/2"DIA. B.C.
                  POLYVINYLCHLORIDE
                  PLASTIC BATTERY CASE

                  YELLOW EPOXY PAINT
  AS SHOWN

  FINISH

  AS SHOWN


      SCALE
              4 IN.
              IOCM.
     GREAT  LAKES  -  ILLINOIS
      RIVER BASINS  PROJECT
         NAVIGATION  LIGHT

            NOT TO SCALE
    US DEPARTMENT Of THE INTERIOR
FEDERAL WHITER POLLUTION CONTROL ADMHN
Great Lak«t Rtgion           Chicoqo.iHmou
                                                                          FIGURE  4" 12

-------
TO ANEMOMETER•
               SCALE
           0            4IN.
           I 1111    l.i    I
           r~nrill   I
           0            IOCM
       6V.BATTERY CASE
 13ft
                          DIGITAL  FILM RECORDER
                          MEASURING WIND SPEED
                          a COMPASS BEARING —.
111
(
^
/




Bl-
\
                                             INT II
                10*-
                                                                              35"
                                                    GREAT  LAKES —  ILLINOIS
                                                     RIVER BASINS  PROJECT
                                                         WIND RECORDER
                                                   U.S DEPARTMENT OF THE INTERIOR

                                               FEDERAL WATER POLLUTION CONTROL ADMIN
                                               Great Lakes Region           Chicago,Illinois
                                  60
FIGURE 4-13

-------
-
32
                     I3/32"DIA. 4 HOLES
              ALUMINUM CUPS
                                                       A-268 MAGNETIC SWITCH
                                                        ASSEMBLY
                                                            SCALE
                                                                    4IN.
                                                               I   I  T
                                                                   IOCM.
MATERIAL
ALUMINUM WITH STAINLESS STEEL FASTENERS

 FINISH
 BLACK ANODIZE FINISH ON ALUMINUM CUPS
GREAT  LAKES  -  ILLINOIS
 RIVER  BASINS  PROJECT
                                                HEAVY DUTY ANEMOMETER
                                                US DEPARTMENT OF THE INTEWO*
                                             FEDERAL WATER POLLUTION CONTROL AOMtN
                                             SrMl Lok**R«Qion           CMcogo.lllmoii
                                                                      PK3URE  4-14

-------
                                       ALUMINUM PIPE 1-1/4"
                                       1.66 O.D. X .140 WAUL.
                                       LENGTH AS REQUIRED
                                                   GALVANIZED STEEL
                                                   LIFTING EYE
  IDAY-GLO FIRE ORANGE)
                             U.S.  GOVERNMENT  PROPERTY
                                   KEEP OFF
ALUMINUM LEGS (3)
MARINE PLYWOOD PLATFORMS
 (YELLOW)
                                                                           30 DIA.
FOAM
2 L8/FT3
   MATERIAL
   AS SHOWN

   FINISH
   AS SHOWN
   SCALE
            4IN.
I I I I
                            IOCM.
   NOTE
       PAINT LEGS 8 BUOY DAY-GLO FIRE ORANGE
       WITH CLEAR ANTI-FADE FINISH COAT.
GREAT  LAKES  -   ILLINOIS
 RIVER BASINS PROJECT
                                       INSTRUMENT BUOY
                                          TOROIDAL SHAPE
                                           NOT TO SCALE
                                                   U.S DEPARTMENT OF TH£ INTEWOK
                                               FCOCftAL WATER POL LUTWN CONTKOL AOMIN
                                                    Luk«* fUflion           Chicago,
                                                                         FK3URE  4-15

-------
                                CAST IRON
                                EYE
   144
WATER
LINE-r
CAN FLOAT 7

SPAR BUOY — ••


                                7/8" GALVANIZED
                                    IRON PIPE
                                COTTER
                                PIN

                                WASHER
2
8" -
2'
i
4"
*"
2"
* -„
\ 2

1 , ..
r \ '
i, ,!'
                                6  DIA.
                                STYROFOAM
                                                         TOP VIEW

                                                        (BOTH ENDS)
                                35 GAL DRUM (13261.)
                                (DAY-GLO FIRE ORANGE)
                                 STEEL BAND-BOLT,
                                NUT, 8 CHAIN.
                                                         FRONT VIEW
                                                         CAN FLOAT
MATERIAL
AS SHOWN

FINISH
AS SHOWN
        5  DIA.
        LEAD WEIGHTS
    SCALE
0           4IN.
HIM   i   i   i

             10 CM.
                   SPAR BUOY
                                                   GREAT  LAKES  -  ILLINOIS
                                                    RIVER  BASINS  PROJECT
                                                        BUOY  8  FLOAT
                                                          NOT TO SCALE
    U S DEPARTMENT OF THE INTERIOR
FEDERAL WATER POL LUTION CONTROL ADMIN
Gr«ot Lokt* Rtgion           Chicago.lllmois
                                                                       FIGURE  4-16

-------
water and the anchor ie dropped.  The surface buoy 1* then launched and
its anchor is dropped vhea the line between anchors becomes taut.
       Retrieval of a  station  array  is  staple and consists of first
lifting the surface buoy followed by the  remainder  of  the  array  in
order.

       A winter array is  launched  and  retrieved in a similar manner.
A lighter concrete anchor is used for the  surface  buoy  part  of  the
system in winter, since it must moor only a small recovery buoy (Figure
       Some  difficulties  were  expected  in  the  mooring  system and
several have arisen.  The main problems have been in  the  instrumented
surface buoy mooring.  Apparently,  the  mooring  line  near the anchor
often  was  abraded by the anchor, setting the buoy adrift.  Polypropy-
lene rope, used  because of  its strength, buoyancy,  and resistance to
chemical and organic decay is, unfortunately, easily abraded.

       Another problem with the  surface  buoy has  been that  it would
capsize during storms.   The  buoy is just as stable inverted as  right
side  up.   Chain  in  the  mooring line lessened the frequency of this
occurrence but did not eliminate it.  It became a major problem in Lake
Erie because  of short steep waves in shallower water.   It finally was
overcome by placing a 3-m length of railroad rail in the mooring line.

       A weak link was put into the surface buoy mooring line to elimi-
nate the  possibility  of  breaking  the  mooring line when pulling the
anchor.  In Lake Michigan the  weak link worked well, but  in Lake Erie
it was unsuccessful  apparently due to high frequency stresses  of wave
action.  Consideration had not been  given to the  results of weak link
breakage while  the  stations were unattended.  When breakage occurred,
the  surface buoy was then anchored to  the meter by a very  long line.
This line then wound around the instrument array, the line was abraded,
and the buoy was set adrift.

       A major problem in the work on Lake Michigan was inadequate nav-
igation.  Losses due to navigation  have not occurred since the vessel,
Telson Queen,  was  contracted  as the survey vessel.  This vessel  was
equipped with radar, gyro compass, and radio direction finder.

       Some equipment and/or data have been  lost because of vandalism,
passing ship  damage, ice damage, corrosion, wave hammering,  and array
assembly errors.  All of these losses were relatively minor.

       Except for the weak links, there have  been  no failures because
of exceeding the working strength of materials. Tables 4-1 and 4-2 list
the more important specifications of equipment which apply to mooring.


                                   6k

-------
                              TABLE 4-1

                 SPECIFICATION'S (W MEXERIH EQUIPHEMT
                 Buoyancy
Item
      Operating
Lbs   Depth (M)  Construction
Surface buoy   2,270   5,000

Recovery buoy     36      80       18

Subsurface buoy  227     500       18

Current meter    -13*6   -30    2,700

Temperature       -2.3    -5    1,350
  recorder
Recovery Ihst.    -4.5   -10    1,350
Tension Strength

  Kg      Lbs

3,178   7,000
                 Fiberglass-
                  wrapped styrofoam
                 Fiberglass-
                  wrapped styrofoam
                 Fiberglass-
                  wrapped styrofoam
                 Aluminum amd        2,270   5,000
                  stainless steel
                 Aluminum and
                  stainless steel
                 Aluminum and
                  stainless steel
6,810  15,000
3,600   8,000

1,816   4,000
                              TABLE
Item

£" rope(1.2 cm)
3/4" rope(1.9 cm)
3/8" chaln(9'6 em)
7/16" ahackle(l.1 cm)
I" shackle (1.2 cm)
  V shackle(1.9 cm)
  ' ring (1.2 cm)
5/8" ring(1.6 cm)

5/8" braid(l.6 cm)
7/16" braidd.l cm)

Construction
Polypropylene
Polypropylene
Oalv. steel
OelT. steel
GalT. steel
GalT. steel
Galv. steel

Oalr. steel

Polypropylene
Dacron and
Working
Kg
1,362
2,724
1,362
1,135
1,816
4,086
2,724

3,178

2,724
2,724
""-— "T|~ L"
Strength
Lbs
3,ooo
6,000
3,000
2,500
4,000
9,000
6,000
(yield)
7,000
(yield)
6,000
6,000
                         nylon
                                         Use	

                                     Weak link.
                                     Anchor line.
                                     Anchor line.
                                     Chain connection.
                                     Line and lustrum
                                       connection.
                                     Anchor connection
                                     Current meter lin
                                       connection.
                                     Anchor line
                                       surface buoy.
                                     Instrument line.
                                     Recovery buoy
                                       line.
                                  65

-------
       When a Italian  was  recovered  the  station diagram was used to
recheck the various pieces of equipment used sad all  corrections noted
on the sans sheet.  Damaged rotors, •vanes, or other items were  listed.
The instruments were returned  to the shop and a complete check made on
•various  components and entered against the instrument maintenance log.
When the current meter films vere removed  they  were placed in a metal
container and the instrument  serial number was taped to the container.
Later, a film log sheet (Table V-3) was filled in,  assigning permanent
film serial numbers to each record.   The film series 200 000  has been
assigned  to  the  Great  Lakes.   This  has been further subdivided as
follows:

                       200 000   Lake Michigan
                       210 000   Lake Brie
                       220 000   Lake Ontario
                       230 000   Lake Huron
                       2feO 000   Lake Superior

       The film log sheet was filled in and shipped  with the film to a
film reading agency where the records are filed and the films are  sent
for processing.

       The Inspection Sheets, Tables k-k, 4-5,  and 4-6, were used both
before and after each use.  A file was kept on each instrument with its
performance and maintenance background.  Proper inspection insures that
data are reliable.

film Processing
               Kodak, 16 •»,,  double X,  panchromatic,  negative  movie
film, Wa 449,  on 30 m  (lOO1)  daylight loading reels was used in the
current meter camera (Figure 4-17) •   The exposed film was delivered to
the processing contractor on 30 m reels in blacktape-sealed cans in the
original yellow boxes which have  been  marked in  accordance  with the
user's own identification and numbering information.

       Upon receipt of the film the contractor  perforated an identify-
ing number  or  code  on  the  tall of each roll and on the flap of the
yellow box from which it was taken.   The  film  was  "tail out" on the
reel.

       All films from a single order were then spliced together head to
tail  for  processing.   This  processing  was  described  as "Extended
Processing."

       A positive  print  was  then  made  of the original film on fine
grain release  film  using  emulsion-to-emulsion  contact  for  maximum
                                    66

-------
Date
Film Serial Mo..

Type of last.
Date/Time Started,


Date/TlMB Ended
Speed of Film (Cont.)_


Lat.:	


Lake
Beginning Ft. Nark_

Batch Ho.
Processing Meg.
Edge Ho.'s Original^


Original Stored
1st Print Stored__


Film to be read

       Continuous^

Recovery Buoy #
Copy
      Geodyne
 CABLE k-3

16 •» FllA
  iFicATica
   AID LOG
      University of Wisconsin
     _Pemanent File

      Other Files
                                          Data
                                            saaa
                    Mo.

           Serial Mo.
           Station Mo.,

           Depth	
           Tine (Interval),


           Long.:	


           Job:
           Fraaes Skipped
           Positive_


           Prints
Quantity
           Interval
           Temperature Recorder


           Wind Recorder #
                                          Sfc. Tencp. Recorder

-------
                                TABLE k-k*

                 INSPECTION SHEET-CURRENT METERS TEAR-DOWN
 8.
10.
11.
Seconds
Board and
Elect, connections
STROBE
a. 	
b.
c. ~
d. 	 Cont. and strobe lights
«. 	 Operational check
CLOCTT"
        Secure
        Elect, connections
        Operational
        Timed
        Can

        Secure
        Elect, connections
        Operational
        Timed
        Gear and shaft
    	 RPM
MOTOR SWITCH
a. 	 Secure
b. 	Elect, connections
c. 	Operational check
CLOCK SWITCH
a. 	 Secure
b. 	Elect, connections
c. 	Arm adjustment
d.      Operational check
MERTmWITCH
a. 	 Secure
b. 	Elect, connections
c.      Functional check
POWBTSWlTCH
a. 	 Secure
b. 	Functional Check
c. _____ Elect, connections
BATTERY
a. 	Secure - no leakage
b.	Voltage
BATTERY CONNECTOR
a.      Elect, connections
        Clean
        Resistance check

        Secure
        Lens tight
        Lens* setting
        Drive engaged
   	 Pulley and rubber
f.      Film record (L, S, H)
VAJffi
a. 	 Clean
b. 	Magnets
c. _____ Bearings
d. 	Adjustments
e. 	Free rotation
f.      No visual damage
                                        12.  VANE FOLLOWER
                                        13-
                                        Ik.
                                        15.
                           16.




                           17.


                           18.


                           19-


                           20.



                           21.

                           22.

                           23.
                                                     Secure
                                                     Leakage
                                                     Bubbles
                                                     No binding
                                                     Disc alignment
                                                     Lite
                                                     Lite pipes
                                                     Viscosity
                                                     Diaphraa
                                                     Clean
                                                     Magnets
                                                     Bearings
                                                     Free rotation
                                                     No visual damage
                                        Elect, connections
                                        I-I lite
                                        10-I lite
                                        Lite pipes

                                        Secure
                                        Leakage
                                        Bubbles
                                        No binding
                                        Disc alignment
                                        Lite
                                        Lite pipes
                                        Diaphram
                                                            connections
h. 	
READ PULSE
a. 	 Secure
b. •"""   Elect.
c. 	Lite
d.  __   Lite pipe
FRAME~AND HARDWARE
a. 	 Clean
b. 	 Secure
"©""KINGS
a. 	 Seats undamaged
b. 	No leakage
OPERATIONAL CHECK
a. 	Advance of film
b.      With film removed
POWEinSWlTCH
a. 	 Continuous
b.      Off
c. ~    Interval
CASE
a.	No visual damage
EXTERIOR BOLTS
a.	Tight
DATE
a. 	 Open
                                    68

-------
                                 TABLE

                 HSPECTIOB SHER-CURREMT MBTIRS BUILD-UP
 8.


 9.



10.
     STROBE
     a. 	Seconds
     b. 	Board and
     c. 	Elect. connec%i<
     d.     ' Coat, and strobe lights
     e.     ' Operational check
     CLOCK""
     a. 	Secure
     b. 	Elect, connections
     c.      Rewind
     d.
13.
     a. _ Secure
     b. _ Elect. connections
     c.    '" Brushes cleaned
     d.      Timed
     e. _ Oear and shaft
     f."~HPM
Ik.
      SWETCH
a. 	 Secure
b. 	Elect, connections
c.   	 Operational check
CLOCK. SWITCH
a. 	Secure
b. "~   Elect, connections
c.      Arm adjustment
d. 	Operational check
MERC. SWITCH
a. 	Secure
b. 	Elect, connections
e.      Functional cheek
POWHU UWlTd
a. 	Secure
b. """""" Elect, connections
c. 'Functional cheek
BATfEY
a. 	Secure
b. """   Toltage
BATTERY CCHOCTGR
a. 	Elect, connections
b.      dean
c.      Resistance cheek
                                        15.
a.
b.
c.
d.
e.
f.
11.  VAMl
             Secure
             Clean
                 1 setting
             firire engaged
             Pulley and rubber
             Fila loaded
     b.      Magnets
     c.      Bearings
     d. 	Adjustments
     e. 	Mo visual
     f.      Free rotation
12.  TAME FOLLOWER
             Secure
             Leakage
             Bubbles
             Mo binding
             Disc alignment
             Lite
             Lite pipes
             Ylscoslty
             Diaphram

             dean
             Magnets
             Bearings
             Free rotation
     _. __^^ Mo visual damage
     ROTCOQLLOWER
     a.      Secure
             Elect, connections
             I-I lites
             10-1 lites
             Lite pipes

             Secure
             Leakage
             Bubbles
             Mo binding
             Disc alignment
             Lite
             Lite pipes
     _. 	Dlaphra*
16.  REAFWLSE
     a. 	Secure
     b.      Elee. connections
     c.      Lite
     d. 	Lite pipes
IT.


18.


19-


20.



21.

22.

23-
     a. 	Ser. no. on outside ease
     b. 	Type of cam (lobes)
     "o"""53ss
     a. 	 Seat clean
     b. __ Properly seated
     QPBfiZrTCHAL CIBCK
     a. 	Without film
     b.      With film
     POWIK ByiTC
     a. 	Continuous
     b. 	 Off
     c.      Interval
     DlSsICAiT
     a.	Installed
     EXTERIOR BOLTS
     a.	Torqued
     max—
     a. 	Open
     b.      Closed
                                     69

-------
                                TABLE 4-5 a


             INSPECTION SHEET - TIMPERA3WRE RECORDER TEAR-DOWN

 1.   GENERAL EXTERIOR
     a.  	 Exterior clean, no damage to case or end plates
     b.  	Case properly seated
     c.  	Tie rod nuts drawn up tight
     d.  	 Tie rod nuts, washers and end plates removed
     e.  	No damage to case sealing surfaces
 2.   OERKRAL INTERIOR
     a.  	 Clock operating - note switch position
     b.  	 Battery voltage checked (record reading)
     c.  	 Graph tracking on spool (indicate end and date on graph)
     d.  	 Indicate length of graph as: long, short, none, normal
     e.       Operational check (indicate type of cam)
 3.   TEMPERATURE SENSOR
     a.  _____ Sensor and components secure
     b.  	 Scribe tracking and secured to shaft
     c.  	Sensor spiral free, no corrosion
     d.  	 Calibration check (record results)
     e.  	 Stops on slide bar properly positioned
     f.  	 Graph removed and identified as to serial number and date opened

             Spools and shafts free and clean, restraining clips secure
     b.  	 Check spring tension of shafts
     c.  	Face plate smooth and clean
 5.   CLOCK MOUNT
     a.  	Mount bracket secure
     b.       Electrically isolated from frame
     c.  	 Air gap between bracket and power switch
     d.  _____ Clock secure on bracket
 6.   CLOCK
     a.  	Elect, connections.
     b.  	Rewind (check and record timing)
     c.  	 Clock micro switch secure and operational
 7.   MOTOR SWITCH
     a.  	 Secured
     b.  	Elect, connections
     c.  	Functional check
 8.   MERC. SWITCH
     a.  	 Secure
     b.  	   Functional check
 9.   POWBTSWITCH
     a.  	 Elect, connection
     b.  	Functional check
10.   MOTOR AND MOUNT
             Elect, connections
             Functional check
             Timed
             Gear and shaft secure
             No binding of gear-train
        	 Motor and mount secure
11.
             Removed battery
             Battery leads checked
             Starting at base all hardware secured
             No evidence of corrosion
             "0" ring grooved free of nicks, burrs, or dirt
             Instrument clean and rotating parts lubricated

-------
                                TABLE l*-5b

            INSPECTION SHEET - TEMPERATURE RECORDER BUILD-UP
                    (WITH UTILITY BATTERY INSTALLED)


12.  	
             Brushes and armature cleaned cad free
             Grov. points cleaned and adjusted
             Leads properly soldered and routed with no strain
             No visible damage to housing; shaft and gear secure
             With motor disengaged, gear-train movement free
             Micro switch secure and operational (leads properly routed)
             Motor gear properly meshed with gear-train
             Motor and mount secured to instrument
        	 Operational and time check
13-
             Installed, check arming and timing
             Leads secure with no damage or strain
             Adequate clearance between elect, connector and motor
             Mount bracket Isolated from frame and power switch
        	 Cam installed (indicate number of lobes)
Ik.  CLOCK MICRO SWITCH
     a. 	 Switch installed
     b. 	Leads properly soldered and routed with no strain
     c. 	 Verify routing of leads to other components
     d. 	Actuator arm adjusted
     e. __3^_ Functional check
15.  TEMPERATURE SENSOR
             Sensor and components secured
             Sensor spiral free and no corrosion
             No evidence of transfer fluid leakage
             No damage or improper routing of transfer tube
             Scribe secured to shaft and indicating approx. temp.
             Face plate smooth and clean
             Spool shaft bushings clean and lubricated
        	 Shaft locking clips secure with free movement
16.
             Free and clean
             Shafts clean and proper spring tension
             Test tape installed, scribe adjusted
             Operational test (2-3 weeks) completed
17.  CALlBTSTIOF
     a. 	 Install new tape, verify hole and sprocket alignment
     b. 	 Calibrate instrument (indicate range)
18.  BATTERY
     a. 	 Voltage (note on tape ser. no., date, and starting point)
     b. ______ Operational check performed
19.  "0" RINGS
     a. 	 Case clean, sealing surfaces free of damage or dirt
     b. 	 "0" rings installed in base and cover
20.  POWER SWITCH
     a. 	 Continuous
     b. 	 Off
     c. ___. Interval
21.  DESS53NT
     a.      Installed
22.  CASl
     a. 	 Case and cover - tie rods installed and nuts torqued
     b. 	 Instrument identified with ser. no. and type of cam
                                    71

-------
                                 TABLE l*-6a

                 INSPECTION SHEET-WIND RECORDER TEAR-DOWN
10.
11.
        	 Seconds
     b. 	Board and components
     c. 	Elect, connections
     d. 	 Cont. and strobe lights
     e. 	 Operational check
     CLOCK
     a. 	 Secure
     b. 	Elect, connections
     c. 	 Operational
     d. 	Timed
     e. 	 Cam
     MOTOR
     a. 	 Secure
     b. 	 Elect, connections
     c. 	 Operational check
     d. 	Timed
     e.      Gear and shaft
     f. 	 RPM
     MOTOR SWITCH
     a. 	 Secure
     b. 	 Elect, connections
     c. 	 Operational check
     CLOCK SWITCH
     a. 	 Secure
     b. 	 Elect, connections
     c. 	Arm adjustment
     d. 	  Operational check
     BATTERY CASE
     a.	Clean
             Cover fasteners secure
             No visible damage
                                   13-
                                   Ik.
             Secure
             Elect, connections
             Operational check
b. 	
c. 	
POWER
a.
b.
c. 	
BATTERY
a. 	 Secure, no leakage
b. 	 Voltage
BATTERY CONNECTOR
a.      Elect, connections
        Clean
        Resistance check

        Secure
        Lens tight
        Lens1 setting
        Drive engaged
        Pulley and rubber
        Film record  (L,S,N)


        Clean
        Magnets
        Bearings
        Adjustments
        Free rotation
        No visible damage
12.  VANE FOLLOWER
     a. 	 Secure
     b. 	 Leakage
     c. 	 Bubbles
     d. 	No binding
     e. 	 Disc alignment
     f. 	 Lite
     g. 	 Lite pipes
     h. 	 Viscosity
     i. 	 Diaphram
     ANEMOMETER
     a. 	Frame secure
     b. 	 Pickup and leads checked
     c. 	 Bearings and free rotation
     d. 	 Cups and shaft secure
     e. 	 Operational check
     BOARD AND LITES
     a.      Board and lites secure
             Elect, connections
             I-I lite
             10-I lite
             Lite pipes

             Secure
             Leakage
             Bubbles
             No binding
             Disc alignment
             Lite
             Lite pipes
        	 Diaphram
16.  READ~PULSE
     a. 	 Secure
     b.    _ Elect, connections
     c.      Lite
     d. 	 Lite pipe
     FRAME AND HARDWARE
     a.      Clean
             Secure
                                   15-
                                        17.
                                        18.
                                        19.
                                        20.
                                        21.
                                        22.

                                        23.
b. 	
"0" RINGS
a. 	 Seats undamaged
b. 	 No leakage
OPEHKTTONAL CHECK
a. 	 Film advance
b. 	With film removed
POWKK SWITCH
        Continuous
        Off
        Interval

   	 No visible damage
EXTERIOR HARDWARE
a.	 Secure
DATE
a. 	 Open
                                     72

-------
                                 TABLE 4-6b

                 INSPECTION SHEET-WIND RECORDER BUILD-UP
 3.
 8.
10.
11.
STROBE
a.
b.
•(•••MUM
C.
a-
e.
CLOCK
a.
b.
c.
d.
e.
MOTOR
a.
b. 	
••^••M
C.
d.
«•••«••
e.
f.
MOTOR
a.
b.
c.

Seconds
~ Board and components
~ Elect, connections
~ Cont. and strobe lights
~ Operational check

Secure
"~ Elect, connections
~ Rewind
~ Timed
~ Cam

Secure
~ Elect, connections
"~ Brushes cleaned
~ Timed
~ dear and shaft
~ RPM
SWITCH
Secure
~ Elect, connections
~ Operational check
                                   12.  VANE FOLLOWER
                                        a. 	 Secure
                                        b. 	 Leakage
                                        c. 	 Bubbles
                                        d. 	 No binding
                                        e. 	 Disc alignment
                                        f. 	 Lite
                                        g. 	 Lite pipes
                                        h. 	 Viscosity
                                        i.	Diaphraa
                                   13.  ANEHOHETER
                                        a. 	 Frame secure
                                        b. 	Pickup and leads checked
                                        c. 	 Bearings and free rotation
                                        d. 	 Cups and shaft secure
                                        e. 	Operational check
                                   14.  BOARD AND LITES
                                        a.      Board and lites secure
CLOCK SWITCH
a. 	 Secure
b. 	 Elect, connections
c. 	Arm adjustment
d. 	 Operational check
BATTERY CASE
a. 	 No visible damage
b. 	 Cover fasteners secure
c. 	 Clean
POWER SWITCH
a. 	 Secure
b. 	 Elect, connections
c. 	Functional check
BATTERY
a. 	 Secure
b.      Voltage
BATTERY CONNECTOR
a.      Elect, connections
        Clean
        Resistance check

        Secure
        Clean
        Lens1 setting
        Drive engaged
        Pulley and rubber
        Film loaded

        Clean
        Magnets
        Bearings
        Adjustment
        Free rotation
        No visible damage
                                             b. 	
                                             c. 	
                                             d. ^^
                                             e. 	
                                        15.  CONFESS
                                             a. 	
                                             b. '~
                                             c. 	
                                             d. 	
                                             e. 	
                                             f. 	
                                             g- 	
                                             h.
             Elect, connections
             I-I lite
             10-1 lite
             Lite pipes

             Secure
             Leakage
             Bubbles
             No binding
             Disc alignment
             Lite
             Lite pipes
        	 Dlaphram
16.  READ PULSE
     a. 	 Secure
     b. 	 Elect, connections
     c.      Lite
     d. 	 Lite pipes
17.  IDENTIFICATION
     a. 	 Ser. no. on outside
     b. 	Type of cam (lobes)
18.  "0" RINGS
     a. 	 Seat clean
     b.	 Properly seated
19.  OPEHRTTONAL CHECK
     a. 	Without film
     b.      With film
20.  POWER-SWITCH POSITION
     a. 	 Continuous
     b.      Off
     c.	Interval
21.  DESB1CANT
     a.      Installed
22.  EXTERIOR BOLTS
     a.	Torqued
23.  DATE
     a.      Closed
                                    73

-------
SPROCKET
                                                           TAKE UP SPOOL
                                                           SUPPLY SPOOL
                                                           GUIDE ROLLERS
                                                           EMULSION SIDE
                                                                 5CM.
                                               GREAT  LAKES  -   ILLINOIS
                                                RIVER  BASINS PROJECT
                                             CAMERA  LOADING  DIAGRAM
                                             U S DEPARTMENT OF THE INTERIOR
                                          FEDERAL WATER POL LUTION CONTROL ADMIN
                                          Great Lukes Region           Chicago,Illinois
                                                                   FK3URE  4-17

-------
clarity of reproduction.  Due to this,  the print and the original were
mirror images of each other as viewed  from the same, such as the emul-
sion, side.   For reference  it should  be noted here that the original
film, when viewed frosi the evulsion side with the beginning  (head)  end
to the right,  concluding  (tail)  end  to the left, had the continuous
channel on top.

       After developing  the  original  and  making the positive print,
both were edge-numbered serially using a common starting point for com-
plete coincidence.   The numbering proceeded from the head of the first
30 m consecutively increasing throughout those spliced together  to the
tall of the last.  The four digit number (0000 to 9999) was preceded by
one of the following letters according to the user's choice:   A, B, C,
D, E, P, G, I, J.

       The original film was then broken down,  rewound head out on the
original spools and returned to the original boxes.

       The prints were broken  down and rewound head  out on individual
30 m reels and boxes.  These boxes are marked according to the perfora-
tions made In the original film and the user's number as it appeared on
the original yellow box.   The prints  were then returned  according to
Instructions.

       Following the processing  the  exposed  film was returned to the
reading  agency  and  the  length of record determined as well as other
information pertaining to the record.

       The clear-edged prints  were visually  viewed for  completeness.
The rotor pulses, timing marks, and direction channels were scanned for
normality (or what was interpreted as normal behavior).   The processed
16-mm films were then ready for conversion to magnetic tape.

       The film was converted on a  Digital Film  Recording  instrument
onto a reel of standard  magnetic  tape.   The tape was recorded at 200
characters per Inch into an IBM 7 channel binary format. Each 50-second
record was read by a flying spot  scanner  at less than 1-second inter-
vals.  The format for reading on magnetic tape varied according to  the
film reading agency used.  One such format was as follows:


Format for Film Beading

a.  120-character Hollerith identification including lake name and
    speed units.
                                   75

-------
b.  120 characters of numeric information

    1 15    film number (5 digits, one xero omitted)                  5
      «
    2 13    Station Kumber                                           12
      3X
    3 13    Depth (meters)                                           18
      3X
    k 12    Tine between observations 20 or 30                       23
      3X
    5 lit-    Starting foot Bark                                       30
    6 12    +Sprocket holes                                          33
      2X
    7 12    Month 01-12                                            37
    8 12    Day 01 - 31                                              39
    9 12    Year (last 2 digits)                                     M
   10 12    Hours                                                    43
   11 12    Minutes                                                  45
      3X
   12 14    Boding foot mark                                         52
      IX
   13 12    +Sprocket holes                                          55
      2X
   Ik 12    Month                                                    59
   15 12    Day                                                      6l
   16 12    Year (last 2 digits)                                     63
   17 12    Hours                                                    65
   18 12    Minutes                                                  67
      IX
   19 Ik    number of read pulses                                    72
      IX

Tape Data Format

      11    type
      13    compass
                     12 such readings
      13    rane
      13    speed

       Current meter speed was recorded in cm/sec.   Current  direction
was defined on  strip charts and  computed magnetic tapes as the direc-
tion toward which the current was flowing.

       Wind speed was recorded in miles per hour.   Wind  direction was
defined on  computed  magnetic  tapes as the direction toward which the
                                   76

-------
wind was bloving.  In processing data l80° was added to computed direc-
tion to present data in the standard manner, i.e., direction from which
the wind was coming.

       A series of records,  with identifying headings,  were then sent
for computer processing.
                                   77

-------
                              CHAPTER 5

                    CURRENT METER FILM PROCESSING
Specifications

       The films  for  both  the  current and wind meters are read by a
film reading agency using a special film scanner  in  connection with a
computer.  Both the compass and vane are read and reported in the orig-
inal Gray Binary Code.  Readings of the vane and compass are taken, the
number of readings varying with the company.

       Rotor speeds are read  and interpreted  by the  computer.   If a
reading is  to  be  meaningful,  at  least  two rotor pulses have to be
interpreted by the film reader.  The instrument has two speed channels,
R-l for every rotor rotation and a  R-10  for  every  10 rotations.  At
times the  R-l  rotor  is  jammed because the signals are too rapid and
cannot be separated in the interval.   This is  then interpreted by the
film reader as a single pulse since the light merely goes off-on-off.

       The R-10 rotor is interpreted initially.  If it is meaningful it
is reported on  magnetic tape.   If  it  is  not, then the R-l rotor is
interpreted.  If meaningful information is available  from the R-l,  it
is reported as a rotor speed;  otherwise, it is reported as too slow or
too fast to be read.  If the read pulse cannot be found at all, this is
reported,  and in this case physical time is kept track of by using the
film sprocket holes as a guide.

       The meter information is noted on magnetic tape in the following
specification format which has  been  adopted by the Project,  the com-
puter  processor,  and  the  film  reading  agencies.  One method is as
follows:

            Each record consists of I,0d0 characters.

            The first record is the  identification record.   The first
60 characters are in IBM tape BCD code (20 = blank).   These characters
are supplied by the reading company.  They include the lake name, speed
unit,  and date processed.   The first character has a one as the first
bit.  The next 60 characters are 20 18-bit binary integers.   The first
19 are supplied by the computer processor.  The 20th is supplied by the
reading company as the constant needed to change the speeds into proper
units (miles/hr for wind records, or cm/sec for current records).

            Succeeding  records  are  broken  up into words of 36 bits.
Each word consists of:
                                   78

-------
       14.-7-7-2-7-9 bits respectively:

         k - diagnostic information

         7 - vane 1

         7 - compass

         2 - type of data word

               0: readable data word

               1: no speed

               2: nonreadable data

               3: end of film
Note;  If the word type is unity,  the indicated speed will be given as
0 or 511  (the upper  speed limit),  depending  on whether it cannot be
read because it is too low or too high, respectively.

       Film is started and ended  as  specified  in the  identification
record.  An end-of-file mark separates each film.

       Bach magnetic tape  is  checked  by  the computer.  The printout
includes  the identification record, the total number of  read  pulses,
and the first three and last three observations in each film.

       Bit 1 (highest order) of the  diagnostic word  (first k- bits) is
zero or one, depending upon whether the speed  is computed from the R-l
or R-10 rotor, respectively.  The R-10 rotor speed should be multiplied
by 2.  This allows better resolutions for speeds.

       The identification  sequence as supplied by the computer service
consists of the following 19 numbers;

       l) Film number (second digit denotes lake — 20 = Lake Michigan,
          21 = Lake Erie, 22 = Lake Ontario, 23 = Lake Huron, 2k = Lake
          Superior).  Ail film codes are in the 200,000 series.

       2) Station number — corresponds to  physical location in lake.

       3) Depth in meters.   A zero depth is not a current meter record
          but is a wind recorder.
                                   79

-------
 4) Time  in  minutes  between  observations — either  20  or 30
    minutes.

 5) Footmark of starting point.  (Footmarks are marks on original
    film at intervals of 1 foot.)

 6) Film sprocket holes.

 7) Month — an integer, 1-12.

 8) Day — an integer, 1-31.

 9) Year — last two digits of the year

10) Hours — based on 2400 hours.

ll) Minutes — an integer, 0-60.

12) Footmark of ending point.

13) Film sprocket holes.

    Month.
                                                      Starting time for
                                                      meaningful data.
      15) Day.

      16) Year.                                      I Ending time for
                                                     I meaningful data.
      17) Hours.

      18) Minutes.

      19) Total number of read pulses (time slices).

Initial Processing

       A copy of the field record sheet giving the salient film Identi-
fications such as  station  number,  starting time, ending time, depth,
time between observations, etc., is sent from the  Project  to computer
processor  and  to the film reading agency.  After film processing, the
reading agency Inspects the original  film  and determines the starting
and  ending  points  of  good  data since there may be a lag of several
hours between the time the Instrument is set in place and the  time  it
starts functioning properly.  The starting time is reported as a combi-
nation of footmarks  (which are numbered on the film at each foot)  and
film sprocket holes.
                                   80

-------
       The 19 elements  of  the  identification  vector  are punched on
paper tape for input to the film scanner.

       A simple consistency check is now performed on these identifica-
tions.  The total number of recordings is:

       a)  given from inspection;

       b)  computable time from the given starting and ending date;

       c)  computable from the starting and ending footmark and film
           sprocket holes.

       Any discrepancy among  these  numbers is investigated and incon-
sistencies  are  reconciled.  At this point the corrected paper tape is
sent on to film scanner.

       The magnetic tape output ia sent by the reading  company  to the
computer processor.   It is  then  copied on a master tape by a special
control data <$2k "MUPBATE" program.

    ;   'The;'data inpu,t tape is composed of an  arbitrary number of films
followed "'"by  "si  double  end  of  file.  Each file contains an arbitrary
number of records in low density. Each record contains 1,080 characters
of odd parity.  The first 120 characters  of  the  first record of each
file contain the file  identification  (i.e., IX, 9A6, A5, 20R3).   The
first  character  is to be skipped.  The second character  to  the 6oth
inclusive is in binary  coded decimal (still  in odd parity).   Each of
the next 20, three-character symbols, is to be interpreted as an 18-bit
binary integer.

       The output tape  is  a master  tape  which contains an arbitrary
number of records  of previous type (except  that density is  now high,
500 PSl) followed by a double end of file.  Column one of the data card
is zero or one,  depending on whether or not the master  tape is blank.
The remaining columns are a job label.

       Required processing:  If the output tape is not blank, files are
skipped until a double end of file  is reached.  A count of  the number
of files is found  and noted.  When new film is copied  onto the master
tape the second end of file is eliminated by being written over.

       As each file is copied, the ordinal number of the file is print-
ed followed by the first 120 characters of the first record in required
format, and the  number of records in that file.  A double  end of file
is written at the end of processing.  The copying  program thus  allows
the handling  of  a single master  tape instead  of its  many component
                                  81

-------
tapes.  Furthermore, it allows a measure of insurance.  In case of tape
failure, there remains the facility to write another master tape.

       The computer is now ready for the processing of the master tape.
This data processing consists of three passes.   Each pass  (except the
first) has as its input the output tape of the preceding pass.

First Pass Program

       The first pass program consists of  the  formation  of a compact
binary Input tape  which the computer can read quickly and efficiently.
This makes it unnecessary to decode the special input formats more than
once.

       This  initial  tape  generation program is buffered, i.e., while
the computer is reading in one record, a previous one is being process-
ed into its individual components  (compass, vanes, speed, etc.).  Vane
readings are averaged into a single vane.   By average,  we do not mean
arithmetic average, since this mean at times yields poor results (i.e.,
the arithmetic average of 0°  and  360°  is 180°).   A short  algorithm
insures  that  vane  readings  are less than 180° apart, by judiciously
adding 360° to the smaller where necessary.   Only then  are the angles
averaged and reduced by 360° where necessary.
                              Figure 5-1
                                   82

-------
       Both the compass  and vane  are given as a clockwise  deflection
from the vertical   (Figure 5-l), the convention used for the vertical y
axis as the major axis,  and the horizontal x  axis  as the minor axis.
The angles,  although  clockwise,  are still  to "be considered positive
angles, since  they are formed from the  major axis to  the minor axis,
Figure 5-2.  In fact, if the above diagram were rotated 90°, its mirror
image would  take on  the more familiar form.   The  basis direction is
defined to be compass + vane + 180° reduced by 360° (or 720°) if neces-
sary, so that the resulting angle is between zero and 360°.  Thus,  the
direction is given  in its meteorological mode, i.e., the direction from
which the wind (or  current)  is coming.   The speed is modified so that
it  is  in  units of miles/hr for wind recorders and cm/sec for current
                                                              y - major
                                                                  axis
                              Figure 5-2
meters.  If the speed is below the instrument range of 0.8 cm/sec it is
recorded as zero. If above the instrument range, over 100 cm/sec, it is
recorded as -2.  If the compass and vane cannot be read (because a read
pulse is missing), the speed cannot be read either.   In this case both
speed and angle are recorded as -1.

       The speed and angle for every time slice are preserved on binary
tape.  In addition, the  complete  identification,  the  total number of
read pulses  (time slices)  and the maximum speed actually attained are
retained.  This maximum speed is needed for future graphing routines so
that the scales can be immediately determined. The total number of read
pulses tells how to read the remainder of the data.
                                  83

-------
       The original magnetic  tape should have cm it the correct vector
identification ariaing from the paper tape prepared at New York Univer-
sity.  However, under the exigencies of production processing, communi-
cations  at  tines  break  down.   At  tines the paper tapes are either
incomplete or totally missing.  In view of the anomalous situation, the
first pass program has  been  modified  to  accept  the  identification
sequence from cards to override the false identification  on tape.  The
calculated  risk  in  this procedure is readily acknowledged.  A single
card out of order can spoil an entire tape and void all future process-
ing based on it.  To insure against this eventuality, a special reading
program has been vritten  to  scan  the  binary  tape and print out all
identifications.

Second Pass Programs

       Second pass programs use the previously  formed binary  tape  as
input.  At present five such programs are being run.

       l)  Six-hour averages

       2)  Histograms

       3)  Envelopes

       k)  Spectral programs

       5)  Filters

       Six-hour averages:   Six-hour averages are computed at 0, 6, 12,
and 18 hours.   These times were selected so  that comparison  could be
made with official weather maps.   Pour parameters  centered around the
midpoint of each 6-hour interval are computed.  These are:

       l)  The number of meaningful data points in the 6-hour interval.
           This may be zero.

       2)  Speed average.

       3)  Angle average. While speeds may be averaged, it is obviously
           impossible to average  angles.   Therefore,  both speeds and
           angles are defined by means of horizontal and  vertical com-
           ponents and each set of components is averaged.  The average
           speed and  angle  are  defined to be the vector resultant of
           their respective average x and y components.

       4)  Standard  deviation  of speeds in order to show a measure of
           dispersion.

-------
       Two days of data including statical depth and date are punched on
cards as a permanent record.  Thus  on  one card we have data for eight
different time slices.  Each slice contains four observations.  Since a
card is limited to 80 columns, we are limited to two columns per obser-
vation.  Both the total number of observations and the speeds obey this
limitation.   The angle is given to  the nearest 10° so that the three-
digit number can be fitted in.   Thus an angle of 2k signifies an angle
between 235° and
       The standard deviation  of speed*  is more  troublesome since it
cannot be reduced to two digits.  However, it can be shown that in most
cases the standard deviation is less than the mean.  Hence the standard
deviation is normalized by dividing it by the mean speed.  This number,
which is unitless, is called the coefficient of variation.  The printed
value is 100 multiplied by this coefficient of variation. The resulting
integer  is  not  permitted to become greater than 99 to insure against
possible (though unlikely) overflow.  In symbols, the number printed is
the minimum of


                90   100 x standard deviation of speed
                yy>          average speed

This unitless number describes the dispersion: the smaller the integer,
the smaller the dispersion. Standard deviations can be readily noted by
multiplying the given number by the average speed.

       The  resulting  data  are  punched on cards and printed.  Sample
output is shown in Table 5-1.

       Histograms ;  Two-dimensional  distribution of speed versus angle
is given for  each  month  of  data.  The distribution of all data of a
stated station at a stated depth  for  all  months is also given.  Each
such distribution is given by 36 angles (each of 10°)  and of 18 speeds
(for  current  meters  3 cm/sec; for wind recorders 5 miles/hr) .  Total
flow is given for each angle and  also  by  total flow which is defined
as FSjNi, where Si is the speed in the i column  (of a  given row) and
NI is the number of observations there.

       The marginal  distributions of both speeds and angles  are  com-
puted and printed.  Each of these, of course,  sums up the total number
of observations.  Note that the number may be smaller  than  the  total
number of time slices,  as observations may be missing at some of these
times.  A sample output is given in Table 5-2.

       Envelopes :   A visual display of  the variations of both  speeds
and angles in a 2-hour period was desired.  A sample result is given in
                                   85

-------
                         TABLE 5-1




                  FORMAT SIX-HOUR AVERAGES




SIX HOURLY AVERAOES-STA. 13 . DEPTH 10 - TINE DTTERVAL 20 HIM.

DATE
4/11/64

4/13/64

4/15/64

4/17/64

4/19/64

4/21/64

4/23/64

4/25/64

4/27/64

4/29/64

5/1/64

5/3/64

5/5/64

5/7/64

5/9/64

5/11/64

5/13/64

5/15/64

5/17/64

5/19/64

5/21/64

5/23/64


H
18
18
18
18
18
18
17
18
13
16
18
18
18
15
6
18
18
3
2
8
12
12
9
9
18
18
17
18
17
18
18
18
18
4
17
18
15
18
18
18
18
18
18
16

D
11
31
25
27
13
12
44
13
28
36
14
18
19
26
74
16
15
16
75
99
46
51
65
66
36
38
33
48
36
18
15
23
16
46
31
9
29
31
13
15
20
16
19
46

AH
1
10
33
0
0
4
6
5
2
3*
35
6
10
9
4
36
36
6
5
29
27
7
2
36
29
33
33
3
1
4
3
6
7
32
29
36
9
4
13
0
0
4
2
32
0
SP
11
17
12
6
14
13
17
13
4
15

7
10
6
5
9
6
2
9
6
5
3

5
5
6
7
14
4
5
4
15
11
5
6
5
3
5
12
5
5
5
6
4

•
18
18
18
18
17
18
16
18
17
17
16
18
18
15
12
18
15
5
5
8
8
8
17
6
17
5
8
18
18
17
18
18
18
9
17
10
4
18
18
4
18
15
18
16

D
18
48
24
23
25
11
41
15
28
18
26
25
19
80
59
35
28
99
74
53
95
26
27
46
21
52
71
17
20
14
8
21
23
97
21
20
42
32
13
34
7
72
27
31

AH
2
35
33
36
1
4
4
4
35
32
35
7
10
5
32
3
4
7
7
32
1
7
4
4
31
4
34
3
2
4
4
5
7
32
33
4
30
7
5
0
0
5
36
2
6
SP
10
17
16
8
11
13
15
11
3
13
10
6
8
4
6
6
5
5
8
3
5
2
3
8
12
8
6
14
5
4
4
16
7
4
5
3
11
3
11
3
5
5
9
4

H
18
18
18
18
18
18
18
18
13
18
18
17
18
12
10
15
16
6
10
5
5
9

7
18
13
18
18
18
18
18
18
18
5
11
5
5
18
18
13
18
18
18
4

D
25
31
31
13
18
8
25
23

12
18
31

42
28
24
33
27
44
67
73
57
63
21
18
54
36
38
25
20
20
15
56
26
30
50
94
63
25
29
17
25
22
41

AH
5
5
1
0
3
6
4
4
35
30
2
9
11
4
32
3
4
9
6
31
7
7
8
26
31
32
33
1
2
3
4
4
7
32
2
34
1
7
6
33
1
0
5
16
12
SP
9
18
10
8
6
13
17
7
5
12
6
7
9
4
3
3
3
2
3
8
8
4
4
4
13
6
14
11
4
5
3
14
5
2
4
3
5
11
8
4
6
7
8
8

H
18
17
18
18
18
18
17
18
15
18
18
16
18
16
15
14
16
5
H
7
11
2
1
18
18
18
17
18
18
18
18
17
7
17
10
15
8
18
17
18
18
17
9
17

D
24
10
13
15
10
26
14
31
47
16
15
25
18
99
41
27
22
97
86
64
26
21
0
32
25
21
33
23
11
22
*9
12
84
28
57
17
83
24
22
14
20
23
95
38

AH
8
5
36
36
2
4
5
2
2
32
3
9
10
6
35
35
5
2
2
5
10
4
9
28
31
32
3
2
2
3
5
2
32
33
32
3
2
8
36
36
3
3
13
29
18
SP
15
13
7
13
12
18
14
4
6
12
6
9
8
6
5
4
3
5
4
5
3
2
3
7
9
11
18
5
5
5
9
14
8
4
5
3
6
15
5
5
4
7
8
4
                             86

-------
                              TABLE 5-2

                      SAMPLE FORMAT OF HISTOGRAM

     TWO DIMENSIONAL SPEED-ANGLE DISTRIBUTION BY MONTH IN LAKE ERIE

           STATION 5.  DEPTH 10.  TIME INTERVAL 20.   AUG.  1964


   SPEED   ^     123^56789
                1.5 ».5 7.5 10.5 13.5 16.5 19.5 22.525.5   ^
 -515
  5   2   15
 15   3   25
 25   4   35
 35   5   ^5
 45   6   55
 55   7   65
 65   8   75
 75   9   85
 85  10   95
 95  11  105
105  12  115
115  13  125
125  14  135
135  15  145
145  16  155
155  17  165
165  18  175
175  19  185
185  20  195
195  21  205
205  22  215
215  23  225
225  24  235
235  25  245
245  26  255
255  27  265
265  28  275
275  29  285
285  30  295
295  31  305
305  32  315
315  33  325
325  34  335
335  35  345
     36  355
1
8
3
4
7
9
10
12
13
25
26
24
15
16
9
7
6
4
6
1
0
7
5
2
2
2
1
3
11
5
17
9
10
7
6
2
4
3
22
17
21
26
46
36
47
52
51
42
25
21
24
18
19
3
3
3
5
8
1
3
3
7
3
3
9
2
10
8
10
6
6
6
2
7
10
4
6
43
47
62
60
50
57
46
27
12
15
7
14
6
0
1
1
2
3
3
6
l
1
0
6
3
3
6
5
3
2
2
10
6
13
6
18
37
43
50
50
22
30
28
21
31
14
13
6
10
3
2
5
2
8
3
5
3
1
2
3
2
3
7
0
2
3
5
0
3
3
8
2
12
17
13
44
22
23
1
12
21
16
7
5
8
0
0
0
3
2
0
2
0
0
2
2
1
3
0
1
3
0
1
0
0
0
4
0
0
0
1
4
4
0
3
2
7
4
1
0
1
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
5
0
0
3
3
3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
0
0
0
0
0
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
17
27
53
l± o
C|i
127
163
174
223
175
187
149
105
111
82
53
50
34
12
7
11
22
19
11
19
13
6
10
31
13
36
30
27
21
17
16
139.5
181.5
406.5
3^9.5
366.0
1,003.
1,255.
1,362.
1,963.
1,240.
1,321.
1,030.
811.5
991.5
663.0
391.5
330.0
339.0
54.0
43.5
82.5
123-0
145-5
70.5
157.5
73-5
33-0
56.0
160.5
73-5
165.0
168.0
130.5
121.5
82.5
111.0
                                   87

-------
Figure 5-3.  Note that  the  number  in the extreme left is the ordinal
day of the year  representing the data.  The speed scale  can be formed
immediately as the  maximum speed  is  known.   Instrument failure  was
indicated by a random array of speeds.

       Both  the  maximum  and  the minimum angle and speed in a 2-hour
interval were graphed side by side.   If no real data points existed in
the 2-hour interval, no points were graphed.

       At times a series of rotations showed up with an inertia! period
of about IT hours, very close to the local inertia! period which varies
with latitude and is 16.96 hours at ^5°H.

Spectral Analysis

       Spectra! analysis is a technique for  investigating the variance
of a time series.   It permits finding the individual components of the
variance.  Any marked peak in  the  spectrum  graph is interpreted as a
vital frequency. The total area under the graph is exactly equal to the
variance.   Thus,  spectral analysis,  unlike harmonic analysis, allows
one to determine the sizes of the important  frequencies  without  pre-
knowledge of their locations.

       The key number in spectra! computations is an integer called the
lag.  The greater the lag, the more resolution one gets in studying the
spectrum. The Nyquist Frequency is defined as 1/2/\ T where /\ T  is the
time between observations.   The last  element  of the spectrum  always
corresponds to this Nyquist  Frequency.  A lag of  M will break up this
basic frequency into M parts.

       Thus to determine long periods, i.e., small frequencies, we need
large lags.  Often this is  impractical  because  the  shortness of the
series  does  not  allow long lags to be used; and, as a rule of thumb,
there is nothing to be gained by using  lags much longer than one-tenth
of the length of the series.

       One way around  this  difficulty  is to filter the series with a
low-pass filter  (with consequent loss  of high  frequencies,  although
this is usually not serious) and then to decrease the Nyquist Frequency
by taking,  say, every fifth data point.  A smaller lag, therefore, can
be used to give information on the required low frequencies,  as illus-
trated by the following example.

       The current meter and  wind recorder  record every 20 or 30 min-
utes.  The Nyquist Frequencies for  these  two  sampling intervals  are
respectively, 1.5 and 1.0 cycles per hour (cph).  If we apply a digital
filter to the data which does not pass frequencies above 0.25 cycle per

-------
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                         "59"
FiGuPf  5-3

-------
hour, then 0.25  cph is an "effective" Hyquist  Frequency.  This  means
that we can subsample the 30-minute records every kth data point (every
2hr) and  subsample  the  20-minute records every 6th data point (every
2hr).  Subsampling every 2 hours yields a Nyquist Frequency of 0.25 cph.
Thus, the number of filtered data points which  we  must  lag with each
other has  been  reduced four- or sixfold.  Since the frequency resolu-
tion of a spectral analysis is given by fN/m (where m = number of lags),
it can be seen that, if a specific resolution is desired, the effect of
reducing fjf is to enable  one  to  reduce  m also.  Thus, filtering and
subsaapling the records, has enabled us to obtain good spectral resolu-
tion in the frequency range 0.0 - 0.25 cph  using  fewer  lags and data
points than if we had not performed these operations.

                                Formulas

       Suppose the series is x(t) for t = 1, H and M is the maximum lag.
The following  sequence of operations  computes the power spectrum S(i)
for i » 1 to M.

       a) The mean of the series is removed, i.e., x(t) is replaced  by
                                  1=1

       b) The correlation function Q(i) is computed for 1=0  to  M,
where

                                  N-l

                       Q(l)  -    £  x(t)   .  x(t +1) /  (H - i)

                                  t=l

Q(0) is the variance of the series.

       c) Let F(i) be the Fourier cosine of Q(i) for i =0 ... M,  i.e.,

                                   M
where Q(0) and Q(M) are replaced by half their values.
                                   90

-------
       d) The spectrum  function  is  finally computed by smoothing the
above cosine transform by the 3-point Banning formula:
                    =  .25 Fi+1  +  .5 F±  +  -25 F^!

where

              P0  =  F2  and  FM + i  =  FM . I


are defined to give Meaning to 8(0) and e(M+l).

       e) The frequency  in cycles  per unit  time is computed in terms
of the lag number as follows:


              FRE(i)  =
                         2M  .  delt
for i = 0 to M where delt is the time between observations. If the time
is measured  in  hours,  the  frequency  will  be  given  in  units  of
cycles/hour, etc.  The period is the reciprocal of frequency.

       The power spectrum  at  a particular  frequency is the amount of
power or variance in the frequency  band centered around  the frequency
in question.  The width of this frequency is given by
                        2N delt
                            Cross Spectrum

       A cross spectrum  is a generalization  of spectrum  analysis  as
applied to two series.  It is actually made up of two numbers for every
frequency.  One is called the co-spectrum  while the other is the quad-
rature spectrum.

       If the cross spectrum of a series with itself is  taken, the co-
spectrum  turns  out  to  be  the spectrum  of  the  series  while  the
quadrature spectrum is identically zero.
                                   91

-------
       The formulas  are  quite analogous.  Again we remove the average
from both sides.  We then lag both series separately.


                    =    £x(t)  y(t + i)
                               H - i

                               + i)  y(t)
                               N - i

We now define the correlation function  to be half the sum and half the
difference of P and Q, i.e.,
              Q2(i)  =
We now find the  Fourier cosine  transform  of Q^ and the Fourier  sine
transform of Qg.  (The formula for the latter is identical with that of
cosine  transform of  replacing  cosine  with  sine.)  After respective
three-point smoothlngs as'before, the resulting functions  are  defined
as the co-spectrum (Co) and quadrature (quad).

       Coherence, C(i),  is  the  measure  of the relation between both
series at a particular frequency.
                             C02(i)  +  quad2(i)
                               SPl(i)SP2(i)

where SPl(i) and SP2(i) are the respective spectra  of  the  individual
series.  It can  be  shown that coherence must be a number between zero
and  one.  A coherence close to zero  shows  very  little   correlation
between  series.  A coherence close to one means that series are highly
correlated at that frequency.

Graphing

       Digital graphs are especially useful.  For their description,see
Mehr (51).
                                   92

-------
       An analog plotter  was  extensively  used to replace the digital
envelope.

       The resulting graph is both more  accurate and esthetically sat-
isfying. However, its usefulness is marred by the long lag time between
the digital program and its resulting graph for long runs.

Third Pass Programs

       Third pass programs employ 6-hour average cards as input.

       Trajectory programs;  The 6-hour speed  and angle data were used
to plot the path of  a  mythical  point  being  moved  at these average
speeds.  Two days of data were given a single  diagram.   Two  diagrams
made up a  page.  The starting  point was at the center of the diagram.
Succeeding points were designated by succeeding  letters  of the alpha-
bet.  If a letter was missing, it had  obviously been written over by a
succeeding letter.  (See Figure 5-k.)  Major  trends  over  a period of
several days were thus readily observable.

       Maps:  To study the 6-hour data intelligently, it was  necessary
to study data from all  stations at a given depth at a given time.  The
computer printed out a map of Lake Michigan for every 6-hour period for
every  depth  having  data  in  a  key 3-month period (October-December
1963).  Each station was marked by an asterisk in its correct geograph-
ical position. Dots represented the boundary of the Lake.  If data were
present at a particular station, the four  parameters  described  above
(for 6-hour averages) were printed as four integers around the station.
                              10     15

                                  #

                              2       7
       These maps allowed  us to assimilate many terms of data simulta-
neously, as illustrated by Figure 5-5.

Temperature Data

       Hourly temperature data have been obtained from various stations
at several depths.  Computations  are  used to determine the basic fre-
quencies by means of:
                                   93

-------
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-------
 TIME = 12
      DATE -• 2/  9/63
              o   o
                         O 18 12
                            O  .'
                           19 10.
      . O
   18 12
O   O
   29  23 O   O
I0o"
19  II
  18 20  18  16
   O     O    18 17    18 13
  19 II   24 20    O      O     O
               8 21    3 23
DEPTH = 15
                                             6 HOD R   AVE.
                                        No. of Data
                                           Points
                                        Angle
                                        Average
                                                    V*
                                                    29 29
                                              Coefficient
                                              of Variation
                                                (Speed)
                                              Speed
                                               Average
                                          GREAT  LAKES  —  ILLINOIS
                                           RIVER  BASINS PROJECT
                                         FORMAT  OF  MAPPING

                                                   PROGRAM
                                         0 S DEPARTMENT OF THE  INTERIOR

                                    FEDERAL WATER POLLUTION CONTROL  ADMIN

                                    Great Lakes Rtgio"            Chicago.Illinois
                      95
                                                                 FIGURE  5-5

-------
       a)  Spectral analysis.

       b)  Harmonic analysis.

It is known that any finite sequence can be written as a finite Fourier
Series.  It is too costly to compute all frequencies.  However,  a band
of five harmonics  was  taken  around  every suspected major frequency.
Furthermore, the powers at these frequencies were  computed so that the
percentage of the variance of the original series, that  was  accounted
for at each of these frequencies, could be found. Finally, the percent-
age of the variance that  was unaccounted for by any of the frequencies
was noted.

       c)  Regression analysis.

A linear least squares model  was  computed  based  on  particular sus-
pected frequencies.  The standard error and the coefficient of correla-
tion were also computed.   The former is the square root of the average
of the square of the deviations,  while the latter  is a measure of the
percentage  of the  variance that is accounted  for by this  particular
model.

Drogue Surveys

       Drogue surveys of lake currents near  Chicago were undertaken by
the GLIKB Project.  The  mechanical  details are reported in Chapter 8.
The original data consisted of aerial photographs on color film.  Every
drogue was identified by shape  and  color.   Dr. Akira Okubo  of Johns
Hopkins University proposed a series of computations on the data matrix
consisting of the x-y positions of each of the  drogues  at each of the
time slices.  These computations  consisted of the calculation of means
and standard deviations  of x values and y values,  in  both  time  and
space.  For each  time slice,  the center of gravity of the drogues was
found.  The collection of distances between any two points was studied.
Histograms were formed, and moments computed. The results of these com-
putations and their interpretation have been reported by Dr. Okubo.

       Most of the effort expended  was comprised of obtaining the data
needed for the Okubo computations from the aerial photographs. Essenti-
ally the problem consisted of  finding local coordinates for every time
slice, i.e., a common coordinate system had  to be  constructed for all
frames of a particular time slice.  Global coordinates  for every  time
slice also had to be found, i.e., a common  coordinate system had to be
constructed for all time slices.

       It was assumed that the plane was flying level as the photographs
were taken.  This implied that the equations of transformation from the
UV local plane to the xy global plane was:


                                  96

-------
                      x = A(1)U + A(2)V + A(3)

                      y = A(2)U - A(1)(V)

vhere A(l) =^008 9, (2) = /* sin Q in terms of the  magnification fac-
tor, p , the rotation angle 0, and  the translation of the origin of UV
coordinate system to the point A(3), A(l4.) in the xy plane.  Coordinates
of the two fixed points needed to be given in both  coordinate  systems
to determine  the  transformation  constants,  since  this yielded four
equations in the four unknowns A(l) , A(2), A(3), and
       It is  believed  that  more  accurate  results  would have  been
obtained without the assumption that the plane was level.  However,  we
could not proceed  without  it,  since  at times only two common points
were given.  As a matter of fact, at times, even two fixed points could
not be found  which  were  common  to  two successive frames.  In these
cases, a slow moving drogue had to be considered as a  temporary  fixed
point.  Since this assumption was not abused, it caused  no difficulty,
i.e., it was used only between  frames  of the same time  slice and not
between time slices.  Furthermore,  if  the  same drogue was used  as a
fixed point  at  two  separate  times, it was given a different name to
avoid confusion.

       At times as many as five  fixed points  could be found common to
the  successive  frames.  In  these  cases  the  equations  are   over-
determined.  It was decided to  use least squares.  The following quan-
tity was to be minimized:
A(l)Ui + A(2)V± + A(3) -
                                          A(2)U1 -
       Differentiating
following equations:
                 with  respect  to the unknowns A(i) yielded the
          /  e   0   b   c

            0   e   c  -b

            b   c   d   e

            c  -b   0   d
          \
A(2)

A(3)

                                              f

                                              g
                                    97

-------
where :
              b .  £
              8
             •y -


where w represents the weight of a particular observation.  Thus a real
fixed point can be assigned a higher  weighting factor than a temporary
fixed point.  Varying weights are not used in the first run.

       It can easily  be  verified that  the required  solution to  the
matrix equation is
                     (fd - bsx - csy)/Q

              A(2) = (gd - csx + bsy)/Q

              A(3) = (-fb - eg + esx)/Q

              A(10 = (-fc + bg + esy)/Q
                           p p
and where       Q  = ed - b c
The above relations are imbedded in subroutine  TRANS  (NAX, U, V, X, Y,
A) which determines  A(i), ± = 1...k from NAX sets of xy and UV coordi-
nates .

       The first program is  called  COFIX,  the reduction of all fixed
points to  a  common  coordinate system.  At the start, we  were  given
global coordinates of only two points. To find the third point, we were
given local  coordinates  of the two  fixed points and the third point.
We now computed  the transformation and transformed  the third point to
its global coordinates. These coordinates were punched out on cards for
future use and were added to the memory bank of fixed points.
                                    98

-------
       The computation of the fourth  globed coordinate depended on two
or three (in this case) fixed points.  The same  subroutine  was  again
utilized.   At  each  stage, the fixed points were recomputed.  No dis-
crepancy could be found.

       In general, the computation of the Nth fixed  point  depended on
H-l common fixed points to the  global and the local coordinate system.
(In practice, no more than six com»on points  were  found.)  The output
of this program was the deck of fixed points in global coordinates.

       The actual data were now ready  to be  processed and  the global
coordinates  of  all  data  points  in each time slice were computed as
required by the Okubo program.

       The first card was a time slice  identification card telling the
number of frames in the  particular  time slice and  the  corresponding
frame  Identifications.  A frame  identification card was processed for
each such frame.  It consisted of:

       (a)  The number of drogues in the frame.

       (b)  The number of fixed points in the frame.

       (c)  Identification numbers for the fixed points of both x and y
            local coordinates for each such fixed point in the frame.

       Since the number in (b) was assumed no greater than five, it was
possible to get all the information in (a), (b), and (c) on one card in
addition to a job and time slice identification in order to insure that
the cards were in proper order.

       The global coordinates  of these  fixed  points (which were read
into the computer memory) were now called on and the equation of trans-
formation from the frame to the global coordinates was found. The local
coordinates could now be read.  The drogue data were read for the frame
which had drogue  identification, and its corresponding x and y coordi-
nates. It was known from the frame identification how many drogues were
expected.  Then each drogue was transformed  to its global  coordinate.
A check was made to  find  out if a global determination of this drogue
in this particular time slice had been made previously.  If so, the two
determinations were averaged.

       After completing the particular frame, another frame identifica-
tion card was read  and continued as before.  Since the expected number
of frames in a particular time slice was known, the end of a time slice
was known. The list of all drogues was saved for reference in that time
slice with their corresponding global coordinates.
                                   99

-------
       The computer distinguishes between real data and missing data by
denoting the latter by zero. In the printing program, missing data were
denoted by x = 0 and y = o.  The only  point at which a human  might be
confused  was  the  origin,  which might conceivably be (0, 0) or, most
likely, missing.  However, the computer cannot  be  confused since care
was taken  to  add  some  noise,  about 10*25 at each meaningful point.
Therefore, the computer distinguished between a real  zero and a ficti-
tious zero to denote a missing point.  The fictitious zero was actually
zero while the real zero was simply very close to zero.

       Each succeeding time slice was now processed in a similar manner
until all time slices were processed.  The  resulting  tape was used as
input for further processing of the Okubo program.
                                  100

-------
                              CHAPTER 6

                           CURRENT STUDIES
Introduction

       Preceding sections  of this  report  have described the methods,
techniques, testing, and other activities connected  with  the study of
currents  on  Lake  Michigan.  This  Chapter details the results of the
study.

       Before the data from unattended  current  meters and anemometers
can be published or released for further usage, the first step  must be
the assessment  of  reliability  (timing,  direction, and speed) of the
data.  Assuring correct timing is one of the most  difficult  problems.
The clocks may run slow (or fast) by a fraction of a second in  an hour
and  thus  be  inaccurate  for  an hour or more at the end of a 6-month
record.  Using techniques of 2-hour envelopes  (shoving the maximum and
minimum readings in a 2-hour period) and 6-hour averages does not elim-
inate the error but such errors are  insignificant  over  such  a short
period.   In  reporting  monthly net flows and histograms, the probable
error is less than 0.5 percent.

       It was noted early in dealing with the  6-hour averages that the
current speeds responded  to  a wind input.  This response was found in
the  currents  from top to bottom regardless of current direction.  All
speed records were analyzed to correct any  obvious  errors  which  may
have arisen from automatic scanning or instrument deficiencies.

       By comparing, for each instrument,  the  length  of  the records
with the  known  times at which the instrument was set in and recovered
from the Lake, it is possible to arrange the records on a quality scale
as shown in Table 6-1.   Over  half  of  the  records  show differences
between  recorded  time and the known time of less than kO minutes, and
the maximum error for the remaining records, when corrected,  was  less
than 2^ hours.

                              TABLE 6-1
                      TIMING ACCURACY OF CLOCKS           MAXIMUM HOURLY
       QUALITY                                         RAMGE/MONTH CORRECTED
          A                                                   0 to 1
          B                                                   1 to 2.5
          C                                                   2.5 to 5
          D                                                   5 to 10
          E                                                   Over 10
                                  101

-------
       Ranges B, C, and D permit monthly  evaluation but are not usable
for accurate 6-hour averages unless corrected.   Range  E,  unless cor-
rected,  is  considered  poor  quality  and  normally discarded.  On an
average, the maximum time error permitted is limited to 1 percent.  The
quality of the time values is usually based on the percent error in the
total record.

       Direction errors are not difficult to detect unless the meter is
off by an unknown number of degrees.  The instruments are checked prior
to setting  and  after  retrieval  to reduce this error to zero.  Under
certain circumstances the direction is  meaningless,  due to turbulence
or  other  factors;  and a record of this type is discarded.  A certain
objectivity enters into the search for  errors  in  direction.   Visual
scanning of millions of data points reveals certain constantly repeated
patterns.   These  patterns form the basis for ascertaining good versus
bad data.  Water movements, especially direction patterns do not repeat
specific degrees over any long time period.  Thus, a record which shows
repetition of  the  same  degrees  for more than k hours is immediately
suspect.  Figure 6-1 shows a histogram of  data  which  produced  false
modes due to blurring of the light pipes.  Blurring is due to the rapid
fluctuation of the vane  and  the  light pipes appear (when scanning by
electronic methods) as permanently in the "on" position.  This blurring
appears at certain stations and not others.   All  films  were visually
inspected to remove films which had serious blurring problems.  Quality
values  based  on  the  percent of blurring indicate the quality of the
direction data.

       Speed values are scanned similar to directions.   Values below 1
centimeter per  second  (cm/sec)  are discarded.  Long-term high or low
values are questioned and checked against similar  stations nearby.  On
many occasions high values  occur and appear to be due to reading prob-
lems in the automatic scanning of the records.   New reading techniques
have nearly eliminated these errors.  Quality values, based on the per-
cent of spurious  high  values,  indicate  the reliability of the speed
data.

Data Compilation

       After the data had been compiled into the several forms used for
review purposes by computer printouts, the master lists for identifica-
tion were prepared.   Current  data  were identified in master lists by
film number  (200 000 series, see Net Flows) and by station.

       The original station number  in  Lake  Michigan included 6l sta-
tions of which  38  were  actually  used in the study.  One station was
added  (number 62) near the tower erected for  the  U. S. Weather Bureau
at Muskegon,  Michigan.   The locations are shown on Figure 6-2 and are
identified by longitude and latitude in Table 6-2.
                                   102

-------
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-------
STA.I3
                                                                   40 Kilometers
                                                GREAT  LAKES -   ILLINOIS
                                                 RIVER  BASINS  PROJECT
                                                    LAKE   MICHIGAN
                                              CURRENT  STATION  LOCATIONS
                                               U.S DEPARTMENT OF THE INTERIOR
                                           FEDERAL WATER POLLUTION CONTROL AOMIN
                                           ttrtat Lake* Rtgion           Chicogo.llimoi*
                             104
                                                                    FIGURE 6-2

-------
                                  TABLE 6-2

                             CURRENT METER RECORDS
CO  O
                                     co
                                                    II
                                                    o

                                                                          CO
                                                              «
     I.
s
CVJ

                            I
001  010  033  41 °48'    87°20.5'    20.1  03/31/63 1020  07/26/63  1350  2812
003  010  004  42°02.5'
     015  005

004  010  000  42°01'
     015  001
     022  002
     030  044
     022  203
     010  347
     030  368

005  015  197  4l°59'
     030  199
     060  200
     015  324

007  010  120  42°25'
     015  121
     010  185
     010  321

008  060  049  42°23'
     022  056
     030  057
     015  063
     010  065
     015  374

009  022  051  42°23'
     120  052
     030  053
     090  054
     060  058
     015  062

    *Estiaated
             87°32'     19-5  12/17/62  1530  03/22/63  1300  2280
                              12/17/62  1530  03/22/63  1300  2280

             87°20'     46.6  12/18/62  0815  03/22/63  1550  2264
                              12/18/62  0815  03/22/63  1550  2264
                              12/18/62  0815  03/22/63  1550  2264
                              03/28/63  1125  10/15/63  1430  4827
                              11/17/63  1300  04/12/64  0916  3524
                              04/12/64  0825  07/08/64  0705  2077
                              04/12/64  0825  07/08/64  0705  2077

             87°00-     62.5  11/25/63  0900  04/12/64  1455  3342
                              11/25/63  0900  04/12/64  1455  3342
                              11/25/63  0900  04/12/64  1455  3342
                              05/12/64  1035  07/06/64  0855  1318

             87°45'     22.2  07/30/63  1500  11/09/63  1708  2450
                              07/30/63  1500  11/09/63  1708  2450
                              11/18/63  0800  04/02/64  0900  3265
                              04/10/64  1410  06/16/64  1300  1607

             87°25'    100.6  07/30/63  1730  10/16/63  1100  1866
                              07/30/63  1730  10/16/63  1100  1866
                              07/30/63  1730  10/16/63  1100  1866
                              07/30/63  1730  10/16/63  1100  1866
                              07/30/63  1730  10/16/63  iioo  1866
                              11/24/63  1000  04/10/63  1700* 3319

             86°59'    134.4  08/18/63  1330  10/17/63  1035  1435
                              08/18/63  1330  10/17/63  1035  1435
                              08/18/63  1330  10/17/63  1035  1435
                              08/18/63  1330  10/17/63  1035  1435
                              08/18/63  1330  10/17/63  1035  1435
                              08/18/63  1330  10/17/63  1035  1435
                                     105

-------
                            TABLE 6-2 (Continued)

                            CURRENT HETER RECORDS
                                             KJ       H      W
 010  015   050   42°23'    86°38«     66.1  08/16/63  1045  10/17/63  0805  1485
      022   060                             08/16/63  1045  10/17/63  0805  1485
      030   061                             08/16/63  1045  10/17/63  0805  1485
      060   043                             08/16/63  1045  10/17/63  0805  1485
      015   230                             11/25/63  1600  04/15/64  0900  3401
      022   231                             11/25/63  1600  04/15/64  0900  3401
      030   232                             11/25/63  1600  04/15/64  0900  3401
      060   233                             11/25/63  1600  04/15/64  0900  3401
      010   316                             05/11/64  1535  07/05/64  1352  1318
      015   317                             05/11/64  1535  07/05/64  1352  1318
      022   318                             05/11/64  1535  07/05/64  1352  1318

 Oil  015   123   42°21'    86°21«     20.1  08/06/63  0950  11/08/63  1220  2257

 012  010   124   42°46'    87°42'     22.2  07/31/^3  1020  11/10/63  0730  2445

 013  010   236   42°45'    87°21.8f  117-0  11/19/63  1030  04/10/64  1002  3431
      015   237                             11/19/63  1030  04/10/64  1002  3431
      022   238                             11/19/63  1030  04/10/64  1002  3431
      030   239                             11/19/63  1030  04/10/64  1002  3431
      090   241                             11/19/63  1030  04/10/64  1002  3431
      010   350                             04/10/64  0915  07/08/64  1510  2142
      015   351                             04/10/64  0915  07/08/64  1510  2142
      022   352                             04/10/64  0915  07/08/64  1510  2142
      030   353                             04/10/64  0915  07/08/64  1510  2142
      060   354                             04/10/64  0915  07/08/64  1510  2142
      090   355                             04/10/64  0915  07/08/64  1510  2142

 014  022   126* 42°4l'    86°55'    161.0  08/05/63  1530  11/07/63  1800  2018
      030   127                             08/05/63  1530  11/07/63  1800  2018
      060   128                             08/05/63  1530  11/07/63  1800  2018
      120   130                             08/05/63  1530  11/07/63  1800  2018
      150   131                             08/05/63  1530  11/07/63  1800  2018

 015  022   183   42°44'    86°35f     87.8  08/05/63  1900  12/11/63  1030  3063
      010   242                       89.6  11/26/63  0830  04/15/64  1200  3388
      022   244                             11/26/63  0830  04/15/64  1200  3388
      060   246                             11/26/63  0830  04/15/64  1200  3388
*Previously labeled 200 174.

                                       106

-------
                             TABLE 6-2 (Continued)

                             CURRENT METER RECORDS
                                                                           CO

                                                                      B    1
                                              25
 016  010  133  42°44'     86°15'    20.1  08/04/63  1720  11/08/63  0900  2296

 01?  010  008  43°08f     8T°51f    21.9  12/01/62  1035  Ok/19/63  1100  3096
      015  180                             07/16/63  1000  11/21/63  0830  3070
      015  188                             11/21/63  0900  04/02/64  1515  3196
      010  356                             04/02/64  1615  07/09/64  1225  2118
      015  357                             04/02/64  1615  07/09/64  1225  2118

 018  010  009  43°09'     87°28-    79-8  11/29/62  1550  04/20/63  0900  3401
      030  012                             11/29/62  1550  ok/20/63  0900  3401
      060  191  43°08«     87°24.5'         11/21/63  1300  04/09/64  1236  3360
      030  192                             11/21/63  1300  04/09/64  1236  3360

 020  015  015  43°08f     86°32'   104.2  11/28/63  1530  Ok/22/63  1345  3478
      030  017                             11/28/63  1530  Ok/22/63  1345  3478
      090  019                             11/28/63  1530  Ok/22/63  1345  3478
      022  137                             07/12/63  1115  11/07/63  1330  2834
      060  139                             07/12/63  1115  11/07/63  1330  2834
      090  140                             07/12/63  1115  11/07/63  1330  2834
      010  247                             12/07/63  0930  04/15/64  1830  3070
      060  251                             12/07/63  0930  04/15/64  1830  3070
      010  306                             05/10/64  1005  07/05/64  0745  1342
      015  307                             05/10/64  1005  07/05/64  0745  1342
      022  308                             05/10/64  1005  07/05/64  0745  1342
      030  309                             05/10/64  1005  07/05/64  0745  1342
      090  311                             05/10/64  1005  07/05/64  0745  1342

 021  010  330  43°08'     86°19T    18.3  07/12/63  1230  06/02/64  1330   *

 027  010  Il6**44°03'     87°33'    32.3  08/21/63  1000  10/28/63  1605  1638
      022  118                             08/21/63  1000  10/28/63  1605  1638
      015  212                             12/04/63  0845  04/23/64  1020  3385
      010  358                             04/23/64  1020  07/10/64  0600  1868
      015  359                             04/23/64  1020  07/10/64  0600  1868
      022  360                             04/23/64  1020  OJ/IO/6k  0600  1868

 028  022  207  44°04.5'    87°l4.5l  137-2  12/04/63  1144  04/23/64  1430  3386
      010  361                             Ok/23/6k  1400  07/10/64  0757  1866
      015  362                             04/23/64  1400  07/10/64  0757  1866
      060  365                             04/23/64  1400  07/10/64  0757  1866
      120  367                             04/23/64  1400  07/10/64  0757  1866

 *Station originally lost, end computed.
**Previously labeled 200 016.

                                      107

-------
                            TABLE 6-2 (Continued)

                            CURRENT METER RECORDS
                                             H
                                                                         CO

                                                            a
029  010  107  44°06.5'    87°00'    157-3 08/20/63  1800  10/28/63  1220  1650
     015  108                            08/20/63  1800  10/28/63  1220  1650
     022  109                            08/20/63  1800  10/28/63  1220  1650
     060  in                            08/20/63  1800  10/28/63  1220  1650

030  015  254  44°04'      86°48'    152.4 12/05/63  0900  04/19/64  0835  3263
     030  256                            12/05/63  0900  04/19/64  0835  3263
     060  257                            12/05/63  0900  04/19/64  0835  3263
     090  258                            12/05/63  0900  04/19/64  0835  3263
     120  259                            12/05/63  0900  04/19/64  0835  3263
     150  260                            12/05/63  0900  04/19/64  0835  3263
     022  300                            04/19/64  0705  07/04/64  0925  1826
     030  301                            04/19/64  0705  07/04/64  0925  1826
031  010  142  44°04'      86°33.3'   70.4 08/20/63  1015  11/06/63  1830  1880
     015  143                            08/20/63  1015  11/06/63  1830  i860
     022  144                            08/20/63  1015  11/06/63  1830  1880
     030  145                            08/20/63  1015  11/06/63  1830  i860
037  030  104  44°50'      87°09f     66.4 08/23/63  0930  10/29/63  1120  1610
     010  261                            12/02/63  0900  04/20 /64  1717  3368
     030  264                            12/02/63  0900  04/20/64  1717  3368
     022  295                            04/20/64  1610  07/03/64  0740  1767.5
     030  296                            04/20/64  1610  07/03/64  0740  1767.5
     060  297                            04/20/64  1610  07/03/64  0740  1767.5

038  010  215  44°97.5'    86057.5'  162.8 12/02/63  1200  05/03/64  1615  3676
     030  218                            12/02/63  1200  05/03/64  1615  3676
     120  221                            12/02/63  1200  05/03/64  1615  3676
     060  289                            04/24/64  1210  07/03/64  1220  1680

039  090  027  44°42'      86°45'    246.9 12/02/62  1550  07/19/63  1000  5490
     150  029                            12/02/62  1550  07/19/63  1000  5490
     210  031                            12/02/62  1550  07/19/63  1000  5490
     240  032                            12/02/62  1550  07/19/63  1000  5490
     022  150  44°45f      86°45'          08/22/63  1630  11/06/63  1045  1818
     030  151                            08/22/63  1630  11/06/63  1045  1818
     120  154                            08/22/63  1630  11/06/63  1045  1818
     180  156                            08/22/63  1630  11/06/63  1045  1818
     150  155* '                          08/22/63  1630  11/06/63  1045  1818

*200 155 mislabeled 200 176.
                                     108

-------
                             TABLE 6-2 (Continued)

                             CURRENT METER RECORDS
                                    a                                     co

  R     co  o      3          5      SCQ      ss        o       L?       owH


  S   «5.  |k, §   ^          ^      £•£•      3        H       O       EH   £ H

 o4o  010  266  44°43»     86°3i'    195-T  12/03/63  1130  04/19/64  1627  3316
      060  270                             12/03/63  1130  04/19/64  1627  3316
      120  272                             12/03/63  1130  04/19/64  1627  3316

 041  010  160  44°39'     86°20'    188.4  08/22/63  1000  11/05/63  1430  1804.5
      015  l6l                             08/22/63  1000  11/05/63  1430  1804.5
      090  165                             08/22/63  1000  11/05/63  1430  1804.5
      120  166                             08/22/63  1000  11/05/63  1^30  180^.5

 046  015  097  ^5°33'     86°3V     ^3-3  10/06/63  Ul5  10/29/63  1855  0557
      030  099                             10/06/63  1U15  10/29/63  1855  0557

 047  010  087  45°22'     86°l4«    159-1  10/04/63  1425  10/31/63  1835  0653
      015  088                             10/04/63  1425  10/31/63  1835  0653
      030  090                             10/04/63  1425  10/31/63  1835  0653
      060  091                             10/04/63  1^25  10/31/63  1835  0653
      090  092                             10/04/63  1425  10/31/63  1835  0653
      150  094                             10/04/63  1425  10/31/63  1835  0653

 048  010  082  45°12'     86°02'     45.4  10/04/63  1115  10/31/63  204o  0658

 054  010  077  45°48.5'    84°44.5f   31 A  09/24/63  1505  10/30/63  2115  0870
      022  079                             09/24/63  1505  10/30/63  2115  0870
      030  080                             09/24/63  1505  10/30/63  2115  0870

 061  010  072  45°27'     86°47'     48.8  09/23/63  1245  10/29/63  1700  0868
      015  073                             09/23/63  1245  10/29/63  1700  0868
      022  074                             09/23/63  1245  10/29/63  1700  0868

 062  010  171  Muskegon Tower       15.0  08/04/63*  0930  10/30/63  0800  2086.5
      015  173                             08/04/63*0930  10/30/63  08002086.5
      022  369                             06/22/64** 0815  09/28/64  0800  2352
 *Started on land 40.5 hrs earlier,  time shown is  in water  only.
**Started on land 16 hrs earlier,  time shown is in water  only.
                                     109

-------
       The master list for data identification  by film number is shown
in Table 6-3 and by station in Table 6-2.   These two cross  referenced
lists  permit  rapid  identification of all data from the original com-
puter printouts.  The data included in the master  list  have been cor-
rected for time by methods previously described, a check against master
listings, and individual film scanning.

       In addition to the master  listings  and data printouts, a ques-
tionnaire was prepared for field use.  This questionnaire  is  shown as
Table  6-4  and  was  used  in conjunction with a map of the Lake.  The
questionnaire was directed to local fishermen  who had spent many years
fishing in local areas of the Lake.  The purpose was to obtain detailed
information concerning local areas to compare with other data  obtained
from the current study.  Several of the  questionnaires  were sometimes
used in one  interview and supplementary sheets were added as necessary
to record additional information.  Unfortunately, the data secured were
widely scattered, especially as  to time of occurrence.  After a series
of interviews at three different cities,  the  information obtained was
reviewed and summarized.  The data collected were inconclusive and much
too general in nature to be of any importance.   Accordingly, the ques-
tionnaire method was dropped.  A long-term,  systematic  approach might
produce tangible results from this type of investigation. Fishermen who
have sailed a specific  area  for  many  years are extremely helpful in
gathering general information about that area.

       Table 6-5 includes a brief list of  conversion  factors for easy
reference where conversions are not shown.

Net Flows

       A major objective of the current study was to  determine the net
circulation of  the Lake  and relate this to wind movements for predic-
tion purposes.  Perhaps if there were  direct  relationships they would
have been well understood many years ago.

       Drogue studies  in the upper 1.5  meters (5 feet)  of water show
that the  upper  layers are  directly wind-driven  and respond to  wind
shifts in about 1 hour.  This would  imply that the  immediate  surface
layers will respond to reversals in wind inputs in a matter of minutes.
The depth of  direct wind-driven circulations will vary  from  place to
place, especially if a  thermocllne exists.   The depth also depends on
the wind strength and duration.   Direct wind control of currents under
moderate wind conditions (400 to 500 cm/sec), appears to extend to 3 to
5 meters in  depth.  Below this level a shear zone may exist, depending
on its location, movements in adjacent parts of the Lake, and the pres-
ence or absence of a thermocline.
                                  110

-------
                               TABLE 6-3

                    CUBREHT METER AMD WIND RECORDER
                         RECORDS BY FILM NUMBER
FILM
MO.
200-
000
001
002
004
005
008
009
015
016*
019
027
029
031
032
033
037
038
043
044
049
050
051
052
053
054
056
057
058
060
061
062
063
065
066
067
STATION
oo4
004
004
003
003
017
018
020
027
020
039
039
039
039
001
005
001
010
004
008
010
009
009
009
009
008
008
009
010
010
009
008
008
008
009
DEPTH
00
010
015
022
010
015
010
010
015
010
090
090
150
210
240
010
000
000
060
030
060
015
022
120
030
090
022
030
060
022
030
015
015
010
000
000
FILM
HO.
200-
068
069
070
072
073
074
076
077
079
080
081
082
086
087
088
090
091
092
094
095
097
099
100
104
106
107
108
109
in
115
116**
118
120
121
123
STATION
015
013
010
061
061
061
061
054
054
054
054
048
048
047
047
047
047
047
047
047
046
046
046
037
037
029
029
029
029
029
027
027
007
007
on
DEPTH
(M)
000
000
000
010
015
022
000
010
022
030
000
010
000
010
015
030
060
090
150
000
015
030
000
030
000
010
015
022
060
000
010
022
010
015
015
FILM
NO.
200-
124
126
127
128
130
131
133
137
139
l4o
141
142
143
144
145
150
151
154
155
156
160
161
165
166
169
170
171
173
180
183
185
188
191
192
197
STATION
012
014
014
014
014
014
016
020
020
020
020
031
031
031
031
039
039
039
039
039
041
041
O4l
O4l
041
018
062
062
017
015
007
017
018
018
005
DEPTH
(M)
010
022
030
060
120
150
010
022
060
090
000
010
015
022
030
022
030
120
150
180
010
015
090
120
000
000
010
015
015
022
010
015
060
030
015
 *Nuznber 200
**Mislabeled 200 016
                                  in

-------
      TABLE 6-3 (Continued)

CURRENT METER ADD WIND RECORDER
     RECORDS BY FILM NUMBER
FILM
NO.
200-
199
200
203
207
212
215
218
221
223
224
230
231
232
233
236
237
238
239
241
242
244
246
247
251
254
256
257
258
259
260
261
264
266
270
272
STATION
005
005
004
028
027
038
038
038
017
007
010
010
010
010
013
013
013
013
013
015
015
015
020
020
030
030
030
030
030
030
037
037
040
040
040
DEPTH
(M)
030
060
022
022
015
010
030
120
000
000
015
022
030
060
010
015
022
030
090
010
022
060
010
060
015
030
060
090
120
150
010
030
010
060
120
FILM
NO.
200-
289
295
296
297
300
301
306
307
308
309
3H
316
317
318
321
324
330
334
337
338
339
340
341
342
345
346
347
350
351
352
353
354
355
356
357
STATION
038
037
037
037
030
030
020
020
020
020
020
010
010
010
007
005
021
005
004
015
017
027
028
030
040
007
004
013
013
013
013
013
013
017
017
DEPTH
(M)
060
022
030
060
022
030
010
015
022
030
090
010
015
022
010
015
010
000
000
000
000
000
000
000
000
000
010
010
015
022
030
060
090
010
015
FILM
Kw.
200-
358
359
360
361
362
365
367
368
369
374

























STATION
027
027
027
028
028
028
028
004
062
008

























DEPTH
(M)
010
015
022
010
015
060
120
030
022
015

























              112

-------
                                 TABLE 6-4




                               QUESTIONNAIRE








 Name 	   Age
 Address 	   Telephone
 1.  Type of boat used: 	   2.  Years fished: _



 3.  Season or seasons you fish?



     Spring	  Summer	  Pall	Winter 	



 4.  Area normally fished:     map	   5.  Miles off shore



 6.  Do you fish other areas:  map	   7.  Miles off shore
 8.  Does the current in the area you normally fish, flow in one direction



     during:  Spring	  Summer	  Fall	  Winter 	



 9.  Can you say if a particular wind direction or directions usually occur



     with the currents:



     Spring ________  Summer 	  Pall 	  Winter 	



10.  Have any of your nets broken loose? 	  How many times? 	



     Wind direction during storm: 	  Where did nets go? 	
                                     113

-------
                             TABLE 6-5

                          CONVERSION FACTORS
MULTIPLY

Centimeters
Centimeters/second
Centimeters/second
Cubic feet/sec
Cubic meters/sec

Fathoms
Feet
Feet/sec
Feet/sec

Knots
Knots

Kilometers
Kilometers/hour
Kilometers/hour
Kilometers/hour

Meters
Meters/second
Meters/second

Miles
Miles/hour
Miles/hour
Miles/hour
Miles/hour

Square feet
Square meters
   BY

 0.3937
 0.03281
 0.02237
 0.02832
35-31

 6
30.48
30.48
 0.6818

 1.15
 1.85

 0.6214
 0.9113
 0.5396
 0.6214

 3.281
 3.281
 2.237

 1.609
44.70
 1.467
 1.609
 0.8684

 0.0929
10.76
TO OBTAIN

Inches
Feet/sec
Miles/hour
Cubic meters/sec
Cubic feet/sec

Feet
Centimeters
Centimeters/se c
Miles/hour

Miles/hour
Kllometers/hour

Miles
Feet/sec
Knots
Miles/hour

Feet
Feet/sec
Miles/hour

Kilometers
Centimeters/sec
Feet/sec
Kilometers/hour
Knots

Square meters
Square feet
                                Ilk

-------
       The studies in the Chicago area were about 2 km (1.25 miles) from
shore in 8.2  meters  of  water.   There  is  no doubt that the 6-meter
drogues are influenced less by winds than by  bottom  topography.  They
are also affected by shifts in currents in the upper layers.  Table 6-6
illustrates the variation of flow found in the 1.5-m and 6.1-m drogues.
Approximately 75 drogues were  used for each run  and they were allowed
to drift freely for 3.5 to 5.0 hours.

                              TABLE 6-6

                          DROGUE VARIATIONS
Date
Drogue Depth
in Meters
             Mean Wind
             Direction
             for Previous
             10 Hours
6/25/64
6/26/64
6/26/64
7/15/64
7/15/64
8/15/64
8/16/64
8/16/64
6.1
1.5
6.1
1.5
6.1
6.1
1.5
6.1
59°
46°
46°
80°
80°
33°
15o
15°
                                           Mean Wind
                                           Direction
                                           During Study

                                                47°
                                                61°
                                                61°
                                               122°
                                               122°
                                               171°
                                                94°
                                                94°
Current
Direction
Over Study
Period

   293°
    84°
   280°
   147°
    93°
   1020
   125°
   215°
                            that  the
                                         between the wind and
                          difference
the 1.5-meter depth was about 27° to the right of the pre-
       It is very apparent
currents at
vailing mean wind.   However, when considered against the mean winds of
the previous 10 hours, the angle is increased to 72°. The 6.1-m drogues
varied greatly, both  right  and  left of the wind, ranging from 29  to
l^l0 during the study and from 13° to 126°  for the previous  10 hours.
A weak thermal  discontinuity  occurred  between  the two layers during
the period of study and a shear zone existed.

       When the  summer  thermocline  had become firmly established the
shear zone also existed at the interface between the epilimnion and the
hypolimnion.  In general,  there was found to  be a reversal of current
direction  at  the  thermocline  such that the currents above and below
this  layer  were moving in  approximately  opposite  directions, i.e.,
approximately l80° out of phase.  Such a reversal  is  consistent  with
the presence of  internal  waves  of the first vertical mode, i.e., the
internal waves which would occur  in  a  two-layered  system  and which
exhibit a current  reversal across the boundary between the two layers.
But, in Lake Michigan,  the velocity does not go to zero but appears to
                                 115

-------
spiral to the right in very  confined layers within the upper layers of
the themocline.  A  zero  speed  level  at  the thermocllne-epilimnion
interface was not detected in any of the lakes.   The  so-called  shear
zone appears rather as a very  narrow  level where the currents rotated
(clockwise) through 180° with increasing depth.  This would account for
the wind-current relationships in the thermocline (Vcrber,  85).  Figure
6-3 at  station  8  illustrates  this  shift.  Currents are 180° out of
phase, and  this  is  confirmed  "by cross-spectra between velocity com-
ponents of current meter data above and  below the thermocline.  A high
coherence (0.9) was shown between the two meters at the  local inertial
frequency.

       Internal waves of the first  vertical mode, mentioned above, set
in motion in a lake with relatively homogeneous upper and  lower layers
and a sharp thermocline, would be accompanied by.an upper layer current
similar in speed and direction at ail  depths  down  to  just above the
thermocline,  a  lower  layer current running in the opposite direction
and with little change in depth until just above the bottom.  The rela-
tive speeds of the upper and lower layer  currents  will  depend on the
relative depths of the two layers,  to conform with the condition  that
the local mass transport in each layer must be equal. This was observed
by Mortimer (private  correspondence  and  paper read at the Tenth Con-
ference on Great Lakes Research,  Toronto, April 1967 > to be published)
at  anchor  stations  in  July  and  August  1963  in  mid-lake east of
Milwaukee.  Using current meters, with deck read-out, the vertical cur-
rent structure was measured at 2-meter depth intervals down to 20 meters
and at more widely spaced intervals thereafter for every 2 hours during
three periods covering seven days in all.  The vertical distribution of
temperature was measured at the  same time and a wave-like displacement
of the  thermocline  was  noted  which  exhibited a main periodicity of
approximately 17  hours with a conspicuous component of about half that
period.   This internal  wave increases  in amplitude after a wind dis-
turbance, and  the currents, which were clearly coupled to the internal
wave, also increased  in  speed at  that  time.  The current  direction
rotated clockwise with a dominant period of 17 hours; the highest speeds
observed in  the  upper  layer  were  close to kO cm/sec velocities and
directions were generally similar throughout the upper layer;  a rever-
sal in direction occurred  on passing through the  thermocline; but the
speed of  the  current (also rotating) in the lower layer was very much
less, consistent with the greater depth of that layer.

       These observations confirmed Mortimer's prediction (5^4-) that the
dominant internal wave pattern in Lake Michigan, remote from the shores
and  from the ends of the Lake, could be described in terms of Poincare'
waves with  characteristic periods  close  to  but always significantly
less  than the local inertial period  (17-5 hours  at  the latitude  of
Milwaukee)  and  with  associated  currents  which exhibited  clockwise
                                 116

-------
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                                  117
                                                                           F'GU^F 6-3

-------
rotation having the same periodicity and following an elliptical track.
Mortimer shoved that, just as  standing waves  in a closed  nonrotating
basin can be  regarded as a combination of a progressive wave traveling
in one direction  with an equivalent wave of the same amplitude travel-
ing in the opposite direction, so a pattern of standing  Poincare" waves
can be built up by the combinations of Sverdrup waves traveling in dif-
ferent directions, the Sverdrup wave being the type of long progressive
wave  characteristic of rotating systems  in  regions  remote  from the
boundary.  By contrast,  near the shore where the rotating currents are
ruled out by the boundary, the occurrence of Kelvin waves was predicted.
In these waves, which are also a response to the  Earth's rotation, the
wave crests run  normal  to  the  shore  and  decrease exponentially in
amplitude  away  from  it, and the associated cvrrents,  which decrease
in speed away from the shore,  do not rotate but are constrained to run
parallel to the shore.  In the internal  wave  mode,  Kelvin  waves are
expected  to  be  cf  importance  in Lake Michigan only in a near-shore
strip 10 or 15 km wide.  If waves of this type do, in fact,  occur, the
maximum currents associated with them will be close inshore and running
roughly parallel to the shore but reversing  in direction  from time to
time.  Except for those  waters close inshore, however, the theoretical
picture  suggests that the influence of internal  Poincare-type  waves,
expressed by rotation cf the  currents  at ne&r  inertial  frequencies,
will be  strongly  ftIt  elsewhere in the lake after wind disturbances.
With the destruction cf a  thermocline  in the  late fall, the internal
waves of both classes (Kelvin and Poincare), of course, disappear.

       The above predictions  appear  to  be  directly  relevant to the
Project's  observation."  at  mid-lake  stations  (6 km or more from the
shore).  During stratified  conditions the short-term analysis  of data
does not indicate a wind-driven current system.   The hour-to-hour cur-
rents  are  dominated  by  the  internal wave reginie which receives its
principal energy from  the  wind.   The  internal  wave  regime is also
affected by the Earth's rotation which  tends  to  obscure  the  direct
relationship between  winds as the driving force and currents  produced
by  internal waves.  The internal wave rotation, with a period close to
the inertial frequency, is often altered  by  sudden wind inputs.  This
regime lasts  from late spring (April) into November or early December.
The rotating influence is normally not found in the inshore waters.

       By contrast-  the  winter circulation is less complex and almost
entirely wind-driven.  The major exception  appears  when an  ice cover
occurs or a reverse (winter type)  thermocline  develops in the central
basin.

       A straight prediction  model,  based  on  wind, is not valid for
summer (stratified) conditions in mid-lake. Inshore current patterns in
the upper 5 m appear  to have a wind-driven circulation throughout  the
                                 118

-------
year.  The response to this  system  appears in about 1 hour under mod-
erate wind conditions.

       The inshore zone varies in width and probably extends as much as
10 miles from  the  shore  during  the most favorable conditions and as
little as 2 miles during periods  of  upwelling.   Mid-lake circulation
patterns in winter are not under the influence of internal waves except
under very special conditions. Spectral analysis of current meter data,
for the winter period,  gives no evidence of a dominant frequency which
could control current patterns.  Winter patterns in mid-lake are, simi-
lar to the inshore areas during summer, wind-driven.  The response time
of the mid-lake portion is probably the same as the inshore waters.

       Although the -rinds  are  the  primary  driving  force in winter,
other forces exist which complicate the pattern.  When a  wind reversal
occurs in  one  sector of  the Lake, the remainder of the Lake is at or
attempting to maintain equilibrium under  the  prevailing  wind regime.
No steady-state system  can  exist  while  external conditions are con-
stantly  changing.   ior  this  reason,  Lake  Michigan  probably never
achieves a steady-state or equilibrium condition everywhere at one time.
However, large sectors, such as the southern basin,  do achieve a near-
equilibrium condition. Under these conditions, during the nonstratified
period, a prediction model is applicable.

       Current data, collected  over  Lake  Michigan  were programmed to
display monthly flow *;ata in  10-degree  intervals  in direction and ?-
cm/sec  intervals  in  speed in a two-dimensional histogram.  The total
flows were grouped into 30-degree  increments, i.e., 0°, 30°, 60°, 90°,
etc., and the flows of the  opposite angles subtracted.  The result was
a net or residual flow.  These flows were then translated  into percent.
so there would be continuity from one station to another.

       Records of less than 1 month but more than 20 days were included.
The use of  the net flow value is purely relative and cannot be used to
determine average speed or  varying local flow patterns.  The data show
the long term flow in any single area  and  effectively  mask  out  the
rotary summer flows?.  The histograms can be used to disclose the normal
flow at each station.

       The net windo  were  computed  for  land  stations at Green Bay,
Milwaukee, Chicago, and Grand Haven.  These were  used  in  addition to
the wind  measurements  made  on  the Lake, and are superimposed on the
monthly maps.

       Flow lines have  been  used to connect  one region with another.
Liberty was  taken to smooth out minor differences between stations and
to use conformal flow along the boundaries to the best conformance with
                                  119

-------
the data.  Data for the maps  are  normally  from the current meters at
the 10- and 15-meter depths.

       A hydrostatic head on the Lake is  produced by  an excess of in-
flowing water which makes the Lake surface higher than its outlet. This
head is present  throughout  the  entire  vertical column of water, but
only the volume  above 35 meters  (the depth of the sill of the outlet)
is  affected by an outflow.  The Michigan-Huron seiche, on a short-term
basis, will exceed the normal outflow by more than two orders of magni-
tude.  Net  circulation  patterns  in  the  vicinity  of the Straits of
Mackinac are no doubt affected by  the  seiche.   The  permanent  head,
however, is always present  in  the  entire  Lake.  Although minor, the
head will exert a continual south to north influence.

General Circulation Patterns - Surface

       Two basic patterns of water movement occur in the  upper layers,
one in summer and one in winter.  The effect of each current pattern on
nearshore currents can DC modified by the prevailing or net winds.  The
two winter patterns are shown in Figures 6-4 and 6-5-  Figure 6-k shows
the influence  of  the  north-northwest  winds.  The currents along the
chore move southerly.  This type of flow is usually found from November
through March,  although  not  necessarily  continuously.   It  can  be
expected to occur about 25 to 30 percent of the year,  and  principally
in the winter months.   The mid-lake pattern, shown in both figures, is
a large gyre  that  -otat.es  around  the  basin.   This rotation exists
because of the prevailing wind direction.  The rotation is strengthened
by  the  southwest-northeast  winds  and  slowed  or  reversed  by  the
northwest-southeast w: nds.

       The flow shown  in  Figure  6-5  represents  the south-southwest
winds which will occur normally from January to April, but on an inter-
mittent  basis.   The  shore flow is reversed from that shown in Figure
6-k.  The southwest wind predominates  from January to March and north-
east wind occasionally occurs in April.  This type of flow accounts for
20 to 25 percent of the movements during the year.

       The reverse ?yre does net occur with the same frequency,  as the
•prevailing  winds  normally occur from the south-southwest annually and
may directly influence ;,he continuance of the rotation.

       In summer,  Figures  6-6 and 6-7, the shore currents  a^ain show
the influence of the prevailing winds. The mid-lake flow pattern breaks
down into several  cells  and shows more resemblance to the theoretical
models of standing Poincare waves presented by Mortimer (5*0 and further
discussed  by him in Chapter 10.  The generalized gyre is shown, as the
cell may vary and becomrs very complex.  The entire circulation is dom-
                                   120

-------
                  GREAT  LAKES —  ILLINOIS
                   RIVER  BASINS  PROJECT
                   WINTER  CIRCULATION
                         N-NW WINDS
121
    U S DEPARTMENT OF THE INI £PiOP
FtDERAc  WwTt" POLLUTION CONTROL ADMlN
    Lot"esPegicn           -".hiciji.:, no.o

                         •  30RE 6-4

-------
                  GREAT LAKES —  ILLINOIS
                   RIVER  BASINS  PROJECT
                     WINTER  CIRCULATION
                         S-SW WINDS
                 U.S DEPARTMENT OF THE INTERIOR
             FEDERAL WATER POLLUTION CONTROL ADMIN
             Great Lakes Region           Chicago,Illinois
122
FIGURE 6-5

-------
                  GREAT LAKES     ILLINOIS
                   RIVER BASINS PROJECT
                    SUMMER  CIRCULATION
                         N NE WINDS
                 U S DEPARTMENT OF THE INTERIOR
             rEDERAL WATER POLLUTION CONTROL ADMIN
             Gr«ot Lakes Region           Chicago.Illinois
123
FIGURE 6-6

-------
                   GREAT  LAKES  -  ILLINOIS
                    RIVER  BASINS  PROJECT
                   SUMMER  CIRCULATION
                       S-SW WINDS
                  U S DEPARTMENT OF THE INTERIOR
              FEDERAL WATER POLLUTION CONTROL ADMIN
              Great Lakes Region           Chicago,Illinois
12*
FIGURES-?

-------
inated by the  standing  internal  wave  pattern  during the stratified
period.

       The break between  the inshore and  offshore  circulation appears
to occur at or near where the thermocline intersects with the bottom of
the Lake.  This means that  the location will  vary  as the  thermocline
gets deeper.  In mid-summer the location will be in the vicinity of the
15- to 20-meter contour.   The  circulation  inshore  from this "fluid"
boundary  is  not dominated by the standing internal wave and is influ-
enced primarily by  the  prevailing  winds  and  topography.   The zone
between these regions is no doubt subject to unusual  water  movements.
For instance,  during calm or near equilibrium conditions,  flow may be
determined by proximity to a node or an  antinode of  an internal wave,
and during storm  periods  the  thermocline  may be depressed or tilted
upward and associated with the shear flows reminiscent  of  those found
in the Atlantic Gulf Stream.

       The circulation of the  central portion of the southern basin in
summer strongly suggests a cellular pattern, and clues to the  possible
nature of this have been provided by Mortimer's  1963 (54)  predictions
and by the observations he made to test these in Lake Michigan that year
(private  correspondence and paper presented at the Tenth Conference on
Great Lakes Research,  Toronto,  April  196?*  to be published  in  de-
tail) .   These observations supported  by the Office of Naval Research,
took the form of the current measurements at  anchor  station,  already
described,  in  mid-lake  off Milwaukee (from M. V.  Cisco, of the U. S.
Bureau of Commercial Fisheries)  and detailed  bathythermograph studies
of the temperature distribution in the Milwaukee-Muskegon cross section.
With facilities made available by the Grand Trunk and Western Railroad,
bathythermograph  casts  were  made routinely every 6 minutes (approxi-
mately every 2 km) from the company's  car  ferries  on  their  regular
crossings.   Over the interval July Ik through August 30, 80 cross sec-
tions of temperature distribution were plotted (not all complete because
of rough weather or instrument breakdown)  down to a depth of 55 meters
which includes the upper part of the hypolimnion.   The results of this
study, which are now being presented in a detailed report to the Office
of Naval  Research,  show  large  depth oscillations of the thermocline
often coupled with "upwelling" on one shore  and  "downwelling"  on the
other.  The gradient was relatively gentle when the  observations began
in mid-July,  but  later became much sharper, particularly after strong
northerly winds on August 13 which set up a striking pattern of internal
standing waves across the basin, see Chapter 10, Figures 10-1 and 10-2.

       Although  these  figures  do  not  represent  synoptic  pictures
because the vessel's crossing takes approximately 6 hours, they do dis-
close the main features of the standing  wave  pattern, because the car
ferries pass the mid-lake  position  at roughly every 8 or  9 hours, or
                                  125

-------
approximately every half-period of the predicted 17-hour internal wave.
A mid-lake node at 66 km from Milwaukee clearly persisted for 5 or more
days after the August 13 storm, and there is also evidence, less clear,
of a trlnodal standing wave, probably combined with the uninodal oscil-
lation  (Figure 10-2).  Because the effect of a strong wind disturbance
is normally to produce upwelling of the  thermocline  on  one shore and
downwelling  on  the  other,  the  number  of  transverse nodes for the
resultant internal wave must always be an odd number;  and  it is prob-
able that systems with 1, 3, and perhaps 5  nodes will be the ones most
frequently encountered, often with  a  mixture  of all three in varying
proportions according to the initial conditions.  This will, of course,
make the interpretation  of  any  actual  event complex; and it is only
during relatively simpler periods,  like the one which  occurred  after
the August 13 storm, that the main factors controlling the flow pattern
can be described with reasonable certainty.

       If the standing wave patterns (Figures 10-1 and 10-2) are inter-
preted, as Mortimer has done, in terms of standing Poincare waves, then
this implies that there must also be a nodal structure along the length
of the basin to satisfy the boundary conditions at the ends. It was not
possible, in 1963, to obtain much evidence on the characteristic dimen-
sions of the north-south  internodal distances,  but there were indica-
tions  that  these  might be roughly twice as long as those observed on
the east-west cross section.   If  this  is confirmed by research, then
the circulation cells associated with the internal  waves will be elon-
gated in the north-south direction, but it should be emphasized that if
several longitudinal and transverse nodalities are present, the pattern
will be a  complex one except  during particularly simple episodes.  No
doubt some nodalities will be commonly  preferred, and patterns charac-
teristic for the Lake will recur from time to time.

       It should also be emphasized  that Mortimer's  relatively simple
model of the super-position of Poincare (progressive and standing)  and
Kelvin (progressive;  wave  solutions  have been chosen to apply to the
central portion of the Lake,  between  k2°  and  kk° north, which comes
close to a rectangular north and south channel. For conditions near the
ends of the basin,  which the Project's  studies also covered, the fol-
lowing mathematical models may prove to be more appropriate:  the semi-
circular model (involving Bessel functions)  closing  the end of a long
channel,  or  a  high-eccentricity  elliptical model (involving Mathieu
functions).

       The results  from  the  current meters provide overwhelming con-
firmation that  waves  of  near-inertial  frequency  are  the  dominant
features of the circulation of the mid-lake area of Lake Michigan during
the  period  of  stratification  from  early  spring  right  through to
                                 126

-------
November.  In mid-winter,  when a deep winter  (reversed) thermocline Is
present, the  effects of Internal  waves  on   the  currents can also be
identified.   Two  of  the  best  documented   examples of Internal wave
effects are provided by stations 8 and 9 where the temperature and cur-
rent data were more complete during the summer of  1963  than at other
stations.  These stations are approximately 35 km apart, and one series
of measurements between August 19  and  August 2k,  1963> showed that,
with the top of the thermocline at about 20 meters,  the currents at 15
and 22 m were always in  opposite phase to each other.  Also, for short
intervals,  the  currents  at  any given depth at both stations were in
phase,  suggesting that there was no node (or  an even number of nodes)
between them.

General Circulation Patterns - Subsurface

       Figures 6-8 to 6-lU describe what appears to be the general cir-
culation found in the layers  from  60 to  240 m.   The general pattern
appears to be a counterclockwise rotation through  all  the  layers and
very dominant near the bottom.   Due  to the smaller number of stations
in the subsurface layers,  they were grouped together  to  form one map
for  each  level.   Where net flows reversed at a station, the data are
included on the table with each figure.   Although the counterclockwise
pattern prevails,  it is by no means a permanent circulation.  At least
to 180 m there are several  instances at each  depth  level to show that
the pattern reverses.   At the 210-m level and below, however,  the net
flow pattern may be more stable.  The day-to-day movements suggest that
there is as much variability at 2^0 meters as  at the 10-meter level. In
summer and winter the rotary component of the  horizontal flow patterns,
due to the Internal wave on the thermocline, was found at the 240-meter
level,  portraying movements very similar to surface  movements in  the
summer.

       Figure 6-8, for 60 m depth,  suggests   that the subsurface flows
move across the bar region.  Some of the stations indicate that the net
flows  can  be  in the opposite direction and  reverse patterns no doubt
can occur.  Since the stations include data  collected  under all types
of external forces, it is  understandable  that  reverse  patterns  can
exist.

       On Figure 6-9, at the 90-meter level,   the counterclockwise pat-
tern again is  demonstrated.   The  ridge  is  clearly  evident and two
pockets  are  defined.   Several  stations  still indicate that reverse
patterns are present.

       At 120 meters, Figure 6-10,  the Lake is divided into two parts.
The south  basin and the  north  basin  apparently  rotate in the  same
direction although reversal is still evident from the data,  especially
                                  127

-------
                      6D Meter .Contour
' / Station
/ 5

/ 6

f $

10

13
14

20
28

29

30

37

38
V 4O

Direction of Flow
0
120
o o o
60-330-180
O O
0- 150
o
30
o
180
330°
o o o
330-60-150
300°
o o
60-30
o o
240-30
O O
210-0
o
210
0°

Average Spec^fd
6.3

7.3

6.6

9.1

8.4
10. 0

10.0
4.8

4.3

8.8

8.2

7.5
16.9
6.8
                  GREAT  LAKES -  ILLINOIS
                   RIVER  BASINS PROJECT


                  SUBSURFACE NET FLOWS
                 U.S DEPARTMENT OF THE INTERIOR
             FEDERAL WATER POLLUTION CONTROL AOMtN
             Grtat Lokt* Region           Chicago,Illinois
128
FIGURE 6-8

-------
                           Meier Contour
             Station   Direction of Flow  Average Speed
                          180
                         0°-I80°
                        30° 240°
                             o
                          180
                           0°
5.8
7.6
6.7
2.8
4.5
5.3,
3.7
                   GREAT LAKES  -   (LLINOIS
                    RIVER  BASINS PROJECT
                  SUBSURFACE  NET FLOWS
                  U.S DEPARTMENT OF'THE INTERIOR
             FEDERAL WATER POLLUTION CONTROL ADMIN
             Great Lake* Region           Chicugo.liitnois
129
                                       FIGURE 6-9

-------
         120 Meter Contour
       Direction of Flow
             6°
               o
             30
             150°
             O   O
            0-Z40
            210°
            210°
             0°
             30°
Averoge Speed
    2.3
    5.3
    5.7
   10.8
   10.4
    3.5
    5.3
    5.8
     GREAT  LAKES —  ILLINOIS
      RIVER  BASINS  PROJECT
     SUBSURFACE NET FLOWS
    U S DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL AOMIN
Great Lakes Region           Chicugo.Illinois
                          FIGURE 6-10

-------
      150 Meter  Contour


     Direction of Flow Average Speed
            o
         240
         240"
         330
4:7
7.2
5.6
6.5
     GREAT  LAKES  —   ILLINOIS
      RIVER BASINS PROJECT
     SUBSURFACE NET  FLOWS
    U S DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL ADMIN
Great Lakes Region           Chicago,Illinois
                         FIGURE e-i

-------
                    ISO Meter  Contour
                Station
                Direction of Flow
                Average Speed
                      39
                      210°
                      2.7 cms
                 GREAT LAKES  - ILLINOIS
                  RIVER BASINS PROJECT
                 SUBSURFACE NET FLOWS
138
    US DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL ADMIN
Great Lakes R«gion           Chicago,Illinois

                         FIGURE 6-12

-------
                  Station
                  Direction of Flow
                  Average Speed
,5.7cm».
                  GREAT  LAKES -   ILLINOIS
                    RIVER  BASINS PROJECT
                  SUBSURFACE NET FLOWS
                 U S DEPARTMENT OF THE INTERIOR
             FEDERAL WATER POLLUTION CONTROL ADMIN
             Great Lodes Region           Chicugo.Illinois
133
  riGURE6-l3

-------
                      240 Meter Contour
                 Station
                 Direction of Flow
                 Average  Speed
39
 0°
9.3cms
                   GREAT  LAKES  -  ILLINOIS
                    RIVER  BASINS PROJECT
                   SUBSURFACE  NET  FLOWS
                 US DEPARTMENT OF THE INTERIOR
             FEDERAL WATER POLLUTION CONTROL ADMIN
             Great Lak«» Region            Chicago,Illinois
13*
  FIGURE 6-14

-------
in the north basin.  There is a hint from station 14 that the south end
may have two gyrals occurring at the same time.

       The 150-neter  level, Figure 6-11, shows  that  reverse patterns
still exist from the data at station  30.  The southern basin, although
now comparatively  small, is still a complicated area of more than  100
square  miles.   It  cannot be assumed that an  area of such proportion
exhibits such a simple pattern,  because the currents  are  still quite
complex.   For the first time the pattern in the southern basin shows a
clockwise circulation. The net flow was 180° out of phase from the 120-
meter level.

       Figures 6-12 to 6-14  are based on data from the winter of 1962-
63.  The data indicate a counterclockwise rotation at the three depths.
The data for station 39 shifts nearly 180° from the  180-meter level to
the 210-meter level.   The area of the basin is reduced in size between
the 180-meter level and the 210-meter level.  The change in shape main-
tains  the  same  counterclockwise circulation pattern.  Since stirring
occurs to the bottom of the Lake, the lower levels no doubt can reverse
direction.

       The  circulations  just  described  under  the  heading "General
Circulation," which represent flow over long periods and which  can  be
either clockwise or counterclockwise,  should not be confused  with the
clockwise circulation coupled with  internal  waves  which  is  sharply
tuned to the inertial frequency.  Further examples of this,  and of the
effect of wind on currents and on internal waves, are  given in Chapter
10.

Spectral Analysis

       While the near-inertial frequency of current rotation associated
with internal  waves  in  summer  is very evident for shorter or longer
intervals and the records from many stations,  our  spectra  of current
data are useful in detecting this and other frequencies and facilitated
the interpretation of  a complex picture.  The spectra presented  here,
covering the period November 1962 to July 1964, are summarized in Table
6-7,  and  selected  results  are  depicted graphically on Figures 6-15
through 6-43-  Station locations are shown on Figure 6-2.

       Station 3 is located  near the west shore at the southern end of
Lake Michigan.  The  data  were gathered from January 17, 1963 to March
22, 1963, at 15 meters.  There are no statistically  significant  peaks
in the speed,  Vx and Vy  spectra, the north-south and east-west compo-
nents of the current, although there  was  energy  in  the  long period
disturbances.
                                 135

-------
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                        STATION -  18    20   38
      DEGREES   OF  FREEDOM-  32    31   36


      NO  OF  OBSERVATIONS  -6482 6252 7316
                                                      GREAT  LAKES —  ILLINOIS
                                                       RIVER  BASINS  PROJECT
   WINTER   CURRENT SPECTRA

           LAKE  MICHIGAN
    U S.DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL ADMIN.
Grtot Lakts Rtgion           Chicago,Illinois
                                   130
                          FIGURE  6-15

-------
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DEGREES OF FREEDOM- 20

NO OF OBSERVATIONS - 4455
GREAT LAKES — ILLINOIS
RIVER BASINS PROJECT
STATION — 10

SUMMER CURRENT SPECTRA
LAKE MICHIGAN
U S DEPARTMENT OF THE INTERIOR
FEDERAL WA^ER POLLUTION CONTROL ADMIN
Great Lakes Region Chicago, 'llmois
FIGURE 6-16

-------
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                          HOURS
DEGREES  OF  FREEDOM-  20
DATE - 8/18/3-10/17/3
NO. OF  OBSERVATIONS- 4312
                                              GREAT  LAKES — ILLINOIS
                                               RIVER BASINS  PROJECT
                                             SPECTRA  OF  COMPONENTS
                                                  LAKE  MICHIGAN
    U S DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL  AOMIN
Greot Lakes Region           Chicago,i:hnc/is
                                                                 FIGURE  6-17

-------
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                   Y AXIS   0°- 180°
                                                    GREAT  LAKES — ILLINOIS
                                                     RIVER  BASINS  PROJECT
           100
                        20    16.7
                                HOURS
      DEGREES  OF FREEDOM- 20
      DATE - 8/18/3 - 10/17/3
      NO.  OF  OBSERVATIONS - 4315
SPECTRA  OF  COMPONENTS

     LAKE  MICHIGAN
                                       U S DEPARTMENT OF THE INTERIOR

                                   FEDERAL WATER POLLUTION CONTROL
                                   Great Lakes Region           Chici.g,. '
                                                                        FIGURE 6-19

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DEGREES OF FREEDOM -20
DATE - 5/11/4 -7/5/4


NO. OF OBSERVATIONS - 3057








GREAT LAKES — ILLINOIS
RIVER BASINS PROJECT
SPECTRA OF COMPONENTS
LAKE MICHIGAN

U S DEPARTMENT OF THE INTFRIOR
FEDERAL WATER POLLUTION CONTROL ADMIN
Great Lakes Region Chicago, illmc s
FIGURE 6-21

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          100   50     33     25     20     167
                                  HOURS
     DEGREES  OF  FREEDOM-20
     DATE -  4/10/4- 7/8/4
     NO  OF   OBSERVATIONS  -  6341
                                                   GREAT  LAKES — ILLINOIS
                                                    RIVER  BASINS  PROJECT
     SPECTRA  OF COMPONENTS
          LAKE  MICHIGAN
    U S DEPARTMENT OF THE
FEDERAL WATER POLLUTION CONTROL  ADMIN
Great Lakes Region          Chicago,Hlirois
                                                                      FIGURE  6-22

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                                                       Y AXIS   0°- 180°
                                               14.3    12.5   II.I
                                                   GREAT  LAKES — ILLINOIS
                                                    RIVER  BASINS PROJECT
          100    50    33     25     20    16.7

                               HOURS
     DEGREES  OF  FREEDOM- 21
     DATE-  4/10/4 - 7/8/4
     NO. OF  OBSERVATIONS - 6417
     SPECTRA  OF  COMPONENTS

          LAKE  MICHIGAN
    U S DEPARTMENT OF THE INTERIOR

FEDERAL WATER POLLUTION CONTROL  AOMIN

Great Lakes Region           Chicago,Mlmois
                                                                      FIGURE  6-23

-------
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HOURS
    DEGREES  OF  FREEDOM-  21
    DATE -  4/10/4 -  7/8/4
    NO  OF   OBSERVATIONS  - 6423
                                                 GREAT  LAKES  — ILLINOIS
                                                  RIVER  BASINS PROJECT
SPECTRA  OF
     LAKE  MICHIGAN
               U S DEPARTMENT OF THE INTERIOR
           FEDERAL WATER POLLUTION CONTROL AOMIN
           Great Lakes Region          Chicago,llnno s
                                1*5
                                                                    FIGURE 6-24

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                                                   GREAT LAKES — ILLINOIS
                                                    RIVER  BASINS  PROJECT
          100    50 \  33     23
                               HOURS
     DEGREES  OF  FREEDOM- 20
     DATE -  5/10/4- 7/5/4
     NO. OF  OBSERVATIONS -4029
     SPECTRA  OF  COMPONENTS

          LAKE  MICHIGAN
    US DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL ADMIN
Greot Lok»s Region          Chicugo lliino.s
                                                                       FIGURE 6-26

-------
                                   HOURS
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                                                   GREAT  LAKES  — ILLINOIS
                                                    RIVER BASINS PROJECT
10
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                          HOURS
DEGREES  OF  FREEDOM- 20
DATE- 5/10/4-7/5/4
NO. OF  OBSERVATIONS-4029
16.7
                                                  SPECTRA  OF COMPONENTS
                                                       LAKE  MICHIGAN
                                                  U S DEPARTMENT OF THE INTERIOR
                                              FEDERAL WATER POLLUTION CONTROL ADMIN
                                              Great Lakes Region           Chicago,Illinois
                                                                      FIGURE 6-27

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DEGREES OF FREEDOM - 20
DATE -8/20/3-10/28/3
NO
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GREAT LAKES — ILLINOIS
RIVER BASINS PROJECT

SPECTRA OF COMPONENTS
*J i W » 1 • » f^ V ' w w ITI i ^ 1 » L_ 1 » 1 w
LAKE MICHIGAN

U S DEPARTMENT OF THE INTERIOR
TEDERAL WATER POLLUTION CONTROL ADMIN.
Greot Lake* Region Chicago, Illinois
FIGURE  6-26

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16.7
                                                    GREAT  LAKES —  ILLINOIS

                                                     RIVER  BASINS  PROJECT
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     LAKE   MICHIGAN
         U S DEPARTMENT OF THE INTERIOR

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                                                                       FIGURE 6-29

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GREAT LAKES — ILLINOIS
RIVER BASINS PROJECT
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                                         FIGURE  6-30

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GREAT LAKES — ILLINOIS
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Great Lok«t Region Chicago, Illinois
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GREAT LAKES — ILLINOIS
RIVER BASINS PROJECT
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-------
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Gr«at LoMs Region Chicago, Illinois
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-------
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NO. OF  OBSERVATIONS - 5412
                                                   GREAT LAKES — ILLINOIS
                                                    RIVER  BASINS  PROJECT
SPECTRA  OF COMPONENTS

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-------
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GREAT LAKES — ILLINOIS
RIVER BASINS PROJECT
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-------
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Great Lodes Region Chicugo,lluno,s
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DATE — 9/23/3 - 10/24/3 FEDERAL WATER POLLUTION CONTROL AOMIN
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•LOK FIGURE 6-41

-------
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Great LoMs Region Chicago, (Minces
163
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-------
HOUR
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Great LoK«» Region • -'ic^g.. I "L, s
FIGURE 6-43

-------
           TABLE 6-7



LAKE MICHIGAN CURRENT SPECTRA DATA
STATIOH
03
04


05

07

08




09


10






13




s]
015
010
015
022
015
030
010
015
010
015
022
030
060
015
030
090
015
022
030
060
022
010
015
010
015
022
030
090
010
090
| , DATES OF
*8 SPECTRAL RECORDS
£] START END
005
000
001
002
197
199
120
121
065
063
056
057
049
062
053
054
050
060
061
043
231
316
317
236
237
238
f
if
01/28/63
01/04/63
12/21/62
12/24/62
H/25/63
11/25/63
07/31/63
07/31/63
07/30/63
07/30/63
07/30/63
07/30/63
07/30/63
08/18/63
08/18/63
08/18/63
08/16/63
08/16/63
08/16/63
08/16/63
11/25/63
05/11/64
05/11/64
11/19/63
H/19/63
H/19/63
lip/63
04/10/64
04/10/64
i * / * / >» t
04/10/64
04/10/64
03/22/63
03/22/63
03/22/63
03/22/63
04/13/64
04/13/64
11/10/63
11/10/63
10/16/63
10/16/63
10/16/63
10/16/63
10/16/63
10/17/63
10/17/63
10/17/63
10/17/63
10/17/63
10/17/63
10/17/63
04/15/64
07/05/64
07/05/64
04/11/64
04/11/64
pit /I.I /64
04/U/64
07/08/64
°W/64
07/08/64
07/08/64
S
325-145
0-180
345-165
305-125
25-205
26-206
0-180
0-180
0-180
0-180
0-180


0-180
0-180
0-180
0-180
0-180
0-180
0-180
26-206
0-180
0-180



0-180
0-180
0-180
Is IR «, «. ®
P3 O OO 05 95
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X






X
X
X
X
X
X
X
X
X
X
X
X
X
X

X
X



X
X
X
X
X X
X X
X X
X X
X X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
X X
X X
X X
X X
X
X
X
X
VELOCITY C<
SPECTRA
X
X
X
X
X
X
X
X
X
X
X


X
X
X
X
X
X
X
X
X
X



X
X
X
              165

-------
      TABLE 6-7 (Continued)




LAKE MICHIGAN CURKEBT SPECTRA DATA
£
17

18
20










27

29



30





31



^->
S
x^
010
015
010
015
100
022
060
090
010
060
010
015
022
090
015
022
010
015
022
060
015
030
060
090
120
150
010
015
022
030
a
| , DATES OF
«g SPECTRAL RECORDS
g START END
356
357
009
015
019
137
139
140
247
251
306
307
308
3H
359
360
107
108
109
111
254
256
257
258
259
260
142
1*3
144
1*5
04/02/64
0*/02/6*
12/02/63
11/30/62
11/30/62
07/12/63
07/12/63
07/12/63
12/07/63
12/07/63
05/10/6*
05/10/64
05/10/6*
05/10/6*
0*/23/6*
0*/23/64
08/20/63
08/20/63
08/20/63
08/20/63
12/05/63
12/05/63
12/05/63
12/05/63
12/05/63
12/05/63
08/20/63
08/20/63
08/20/63
08/20/63
07/09/6*
07/09/6*
0*/20/63
0*/17/63
0*/17/63
11/07/63
11/07/63
11/07/63
04/16/64
04/16/64
07/05/6*
07/05/6*
07/05/6*
07/05/6*
07/10/64
07/10/64
10/28/63
10/28/63
10/28/63
10/28/63
04/20/64
04/20/64
04/20/64
04/20/64
04/20/64
0*/20/64
11/06/63
11/06/63
11/06/63
11/06/63
H W «2
tj'ra §» lg ^
^^ ^5 Nl— ' Cyfo C503 C5
0-180 X X

26-206 x
X
325-145 x
0-180 X X
X X
0-180 X X
345-165 x
X
X X
0-180 X X
X X
0-180 X X
X X
45-225 x x
X X
0-180 X X
X X
330-150 x x
X
65-245 x
65-245 x
X
65-245 x
X
20-200 x x
20-200 x x
20-200 x x
20-200 x x
WJJTr.EK liAT,
SPEED SPEC?
VELOCITY O
SPECTRA
x x

XXX
XXX
XXX
X X
X
X X
XXX
X X
X
X X
X
X X
X
X X
X
X X
X
X X
X X
XXX
XXX
X X
XXX
X X
X X
X X
X X
X X
               166

-------
      TABLE 6-7 (Continued)



LAKE MICHIGAN CURRENT SPECTRA DATA
STATION
37




38

39






40


4l



54


61


*~*.
m
1
010
030
022
030
060
030
120
090
150
210
022
030
120
180
010
060
120
010
015
090
120
010
022
030
010
015
022
Is
261
264
295
296
297
218
221
027
029
031
150
151
154
156
266
270
272
160
161
165
166
077
079
080
072
073
074
DATES
SPECTRAL
START
12/02/64
12/02/64
04/20/64
04/20/64
04/20/64
12/02/63
12/02/63
12/04/62
12/04/62
12/04/62
08/22/63
08/22/63
08/22/63
08/22/63
01/22/64
01/22/64
01/22/64
08/22/63
08/22/63
08/22/63
08/22/63
09/24/63
09/24/63
09/24/63
09/23/63
09/23/63
09/23/63
OF
RECORDS
END
04/21/64
04/21/64
07/03/64
07/03/64
07/03/64
05/04/64
05/04/64
03/21/63
03/21/63
03/21/63
11/06/63
11/06/63
11/06/63
11/06/63
04/19/64
04/19/64
04/19/64
11/05/63
11/05/63
11/05/63
11/05/63
10/30/63
10/30/63
10/30/63
10/29/63
10/29/63
10/29/63
I ill
25-205 x
25-205 x
25-205 x x
X X
25-205 x x
X
45-225 x
X
X
X
0-180 X X
X X
0-180 X X
X X
26-206 X
0-180 X
X
0-180 X X
X X
0-180 X X
0-180 X X
110-290 x
110-290 x
110-290 x
350-170 x
350-170 x
350-170 x
WINTER DATA
SPEED SPECTRA
X X
X X
X
X
X
X X
X X
X X
X X
X X
X
X
X
X
X X
X X
X X
X
X
X
X
X
X
X



"1
80u
to
X
X
X

X

X



X

X

X
X

X

X
X
X
X
X
X
X
X
               167

-------
       Station k is located in the southern "basin of Lake Michigan.   It
is an offshore  station and  the data were collected between January k,
1963 and March 22, 1963*   The  recorders were located at three depths;
10, 15, and 22 m. The principal peak located in the 10-m speed spectrum
was at 91 hours (hr) and in the 15- and 22-m speed  spectra at  100 hr.
Another peak in  the  15-m  spectrum  is  at 8.9 hr.  The 91- to 100-hr
period is probably due to long wave pressure systems,  such  as  Rossby
waves.  Apparently there is some forcing by meteorological disturbances
which tend to come at intervals, on the average,  of about k- or 5 days;
and this is confirmed in the spectra of wind data.   The  8.9-hr period
is Lake Michigan's first mode.  The Vx spectra were primarily noise and
no statistically reliable peaks were observed.   The  Vy spectra showed
important peaks at 91 hr in the 10-m record, 8.6 and 111  hr  at  15 m,
and 100 hr at 22 m.

       Station 5  is an offshore station in the southern  basin of Lake
Michigan near the  southeast  shore.   The  data  were gathered for two
depths, 15  and 22 m, during November 25, 1963  to April 13, l$6k.  The
speed spectra contained no  reliable  peaks.   The  velocity components
showed tendencies of energy to peak around 10 and 20 hr.

       Station 7 is an inshore station near the middle  of the southern
basin.  The data were gathered for two  depths,  10  and  15  m, during
July 31> 1963 to November 10, 1963.   The  speed  spectra  have several
peaks which are reliable.   At 10 m there is a peak at ^5-5 hr while at
15 M there  is  a  broad peak between 33 and 50 hr and also one at l6.7
hr.  The energy was generally in the high  frequency  oscillations  for
the speed spectra. In the Vx spectra at the 10-m depth, there are peaks
at 9.1, 18.2, and 50 hr, while at 15 m the peaks are at 18.2, 33, and a
broad peak between 8.8 to 9.5 hr.   The  Vy  spectrum  has a broad peak
between 50 and 100 hr and another peak at  18.2  hr in the 10-m record.
At 15 m there is a peak at 18.2 and 55 hr.

       Station 8 is an offshore  station  in  the southern basin and is
west of the center of the Lake.   The  date  of  these  observations at
depths of 10, 15, 22, 30 and 60 m, was between July 20, 1963 and October
16, 1963.   The speed spectra showed a gigantic inertia! frequency peak
at 17.2 hr in the 22-m record,  17.5  hr  at  10,  15, and 60 m; and an
indication of peaking  around  17  hr at  30 m.   The Vx spectra have a
gigantic peak  at  Yf.k  hr  at  10, 15, and 22 m.  The peaks in the Vy
spectra have identical period  estimates  as  the  Vx  spectra  but are
slightly  smaller  in  energy  magnitude  at corresponding depths.  The
inertial period at this location is 17.8 hr.

       Station 9  is located in the southern basin and approximately in
the center of the Lake, at this latitude. The data for the spectra were
collected between  August 18, 1963 and October 17, 1963-  Speed spectra
                                 168

-------
for depths 15, 22, 30, 60,  and  90  m were calculated from these data.
The velocity component spectra were confuted for 15, 30, and 90 m.  For
the speed spectrum, the principal peak is near the inertia! period with
each depth having its peak at a different tine:  15 m  (17-9 hr),  22 m
(19.6 hr),  30 m (l6.4 hr), 60 m (15.6 hr), 90 m (l4.9 hr).   The  15-m
record also has a significant peak at 8.3 hr.   The Vx  spectrum  gives
estimates  with  a 0.4-hr spread in the location of the inertia! period
from 17.5 hr for 30 m to 17.9 hr for 15 and 90 m. The 15-m spectrum has
another peak at 8.6 hr and the 30-m spectrum has a questionable peak at
8.9 hr*   The  Vy  spectra  show the same period estimates as do the Vx
spectra, Figures 6-17, 6-18, and 6-19.

       Station 10  is an offshore station in the southern basin east of
the center  of the Lake.  The duration of the first data collection was
from August 16, 1963 to October 17, 1963.   The  data were collected at
depths of 15, 22, 30, and 60 m. At 15 m, two significant peaks are com-
puted in the speed spectra, one at 8.5 hr and the other at 17.4 hr.  At
22 m a peak is found at 17.2 hr and an indication of a significant peak
at 8.8 hr.   The 30-m spectrum is noise with more energy evident in the
low frequency.  The 60-m spectrum has a peak at 17.2 hr. The Vx spectra
revealed a peak near  the  inertia!  period  of around 17.k hr at 15 m,
17.2 hr at 22, 30, and 60 m.   Spectral peaks of the first mode of Lake
Michigan  appeared at 8.8 hr in the 15- and 22-m records, 8.6 to 8.8 hr
at 60 m.  For the Vy spectra two peaks are  evident  at  the  following
times and depths:   8.5 and 17.5 hr at 15 m,  8.8 and 17.2 hr at  22 m,
8.7 and 17.2 hr at 30 m, 8.6 and 17.1 hr at 60 m.

       The second set of data was a winter record  between November 25,
1963 and April 15, 1964  at  22 m.  Only velocity components are avail-
able.  The Vx spectra are mostly noise.  The Vy spectra have two signi-
ficant peaks; one at 23-6 and the other at 18.2 hr.

       The third set of data was recorded between May 11, 1964 and July
5, 1964 at 10, 15, and 22 m. The speed spectra show a peaking of energy
around 16 and 24 hr.  The  Vx  spectrum  has two peaks, one at 9*1  and
another at 17.2 hr, in the 10-m record;  and one peak at 18.2 hr in the
15-m record.  The Vy spectrum has the same features excepting the  peak
at 9*1 hr is broadened into a square peak between 8.6 and 9 hr, Figures
6-20 and 6-21.

       Station 13  is  located  in the southern basin of Lake Michigan,
west of the center of the Lake. Winter speed data for depths of 10, 15,
22, 30, and 90 m, during November 19, 1963 to April 11, 1964  show pri-
marily a random response  due  in  part to  a high number of zero speed
readings.   The  summer  data  were recorded between April 10, 1964 and
July 8, 1964 at 10, 30, 60, and 90 m.  The speed spectra show a peaking
of energy around the inertia! period but the Vx  and Vy  spectra show a
                                 169

-------
very strong peaking at the  Inertia! oscillation at  17-4 hr for depths
of 10, 30, and 60 m.   There is evidence of the first free  oscillation
of Lake Michigan in the Vy spectra between 9 and 9.5 hr, Figure 6-22 to
6-24.

       Station 17 is located  in  the  northern part of Lake Michigan's
southern basin near the western shore.   The data were collected during
the sunmer of 1964  from  April  2 to  July 9 at depths of 10 and 15 m.
The principal peak in the 10-m speed spectrum is that near the inertia!
oscillation at 15.4 hr.   There were no statistically significant peaks
in the speed spectrum at the 15-m depth.  In the 10-m record the Vx and
Vy spectra show one significant peak around 16 hr, Figure 6-25.

       Station 18 is an offshore station  located near the northwestern
end of the southern basin.  The data were collected between December 2,
1962 and April 20, 1963 at the  10-m  depth.   The speed spectrum has a
peak  near  the  inertial  period  at  18.8 hr.  The velocity component
spectra have the same peak at 18.2 hr;  however,  due  to an abnormally
high number of zero speeds, the period estimates are not too reliable.

       Station 20 is an offshore station located near the northeast end
of the southern basin.  There  are  four sets of data starting November
1962 and ending July 1964.  The first record is  from November 30, 1962
to April 17, 1963. at 15 and 100 m.  The  15-m  depth shows an inertial
peak at 18.1  hr  but  also contained an unidentifiable peak at 33• 3 hr
which might be due to spurious data.   The 100-m  speed spectrum has an
inertial peak at 18.5 hr and the Vx spectrum's inertial peak is at 17.8
hr.  The Vy spectrum is mostly noise.   The second  record is from July
12, 1963 and  November 7, 1963 at 22, 60, and 90 m.  An inertial oscil-
lation shows a peak at 16.0 hr  at 22 m, 17.4  hr at 60 and 90 m In the
speed spectra.  The Vx spectra showed  a broad inertial  frequency peak
between 16.7 and 17-4 hr at both 22 and 90 m.   The 90-m  spectrum con-
tains a 100-hr peak.   The Vy spectra  show an inertial peak at 16.7 hr
at 22 m and one between 16.7 and 17.4 hr at 90 m.  There is evidence of
Lake Michigan's  first free  oscillation at 22 m  in both the Vx and Vy
spectra.   The third record was  obtained between  December 7, 1963 and
April 16, 1964 at 10 and 60 m.  These  winter spectra show  only noise.
The fourth  record  was gathered between May 10, 1964 and July 5, 1964,
at depths of 10, 15, 22, and 90 m  for the speed  spectra and at depths
of 15 and 90 m  for the velocity component spectra.  The principal peak
in the speed spectra is the one near the inertial period with values of
16.4 hr at 10, 15 and 90 m and 17-5 hr at 22 m.  The Vx and Vy  spectra
have a value of 17.5 hr at both depths for the inertial period oscilla-
tion.  The spectra! peak near Lake Michigan's first mode of free oscil-
lation showed a scatter of values at 8.3 hr (15 m) and 8.5 hr (90 m) in
the Vx spectrum, and 8.5 hr (15 m) and 8.9 hr (90 m) in the Vy spectrum,
Figures 6-26 and 6-27-
                                 170

-------
       Station 27  is located near Manitowoc on the western side of the
Lake. The spectra from this station resulted from data taken from April
23, 1964 to July 10, 1964 at 15 and 22 m.  The 15-m record is not reli-
able due to numerous zero speed readings. The 22-m speed spectrum has a
1?.5-hr inertia! oscillation.  The  Vx  and Vy spectra at 22 m show the
inertia! oscillation  at  17-5  hr.   The Vx spectrum has a smaller but
still significant peak at 8.6 hr which is near  the  first mode of Lake
Michigan.

       Station 29 (inertial period of 17.25 hr)  is an offshore station
located in the approximate center  of the Lake.  The data were gathered
between August 20, 1963 and October 28, 1963 at four depths, 10, 15, 22,
and 60 m. The speed data showed a period near the inertial frequency of
17.1 hr in the 10- and 60-m records, 17.8  hr  at  15 m, and 16.4 hr at
22 m. The Vx and Vy spectra have a very distinct period at the inertial
frequency of 17.25 hr at 15 and 60 m  with the Vx  inertial peak having
slightly more energy than the Vy inertial peak, Figures 6-28 and 6-29-

       Station 30 is in  the middle basin of Lake Michigan, located  to
the east of the center of the Lake.   The  data  were collected between
December 5, 1963 and April 20, 1964.  The speed spectrum for depths 15,
30, 60, 90, 120,  and  150  m shows no statistically significant peaks;
however, there is a concentration of energy in the long period oscilla-
tions.  Several smaller peaks are  computed  in  the velocity component
spectra at depths of 30, 60, and 120 m.   The questionable peaks in the
Vx spectra at 25 hr in the 30- and 60-m  records and 17-5 hr  for 120 m
and in the Vy spectra are around 20 hr in the 30- and 60-m records, and
at 18.1 in the 120-m record.

       Station 31 is an inshore station near Ludington on the east side
of Lake Michigan.   The data were collected between August 20, 1963 and
November 6, 1963.  The speed spectra  show periods ranging from 16.1 hr
at 30 m to 17.0 hr at 10 m, with values of 17.8 to 18.5 hr at 15 m, and
16.3 hr  at  22  m.   (See Figures 6-30, 6-31, 6-32, and 6-33.)  The Vx
spectra show a similar scatter at  all  depths  instead  of  the  usual
sharply defined inertial  oscillation, with 15.3 hr at 10 m, 16.1 hr at
15 m,  16.0  to  16.7  hr  at 22 m, and 16.0 hr at 30 m.  The Vy period
estimate is also scattered, with 15.3 hr at 10 m, 17.0 hr at 15 m, 16.7
hr at 22 m, and 16.0 hr to 17.0 hr at 30 m.   The problem of scattering
is due to the lack of resolving  power  in the spectral analysis proce-
dure; but by using harmonic analysis the scatter is resolvable.

       Station  37  is  a  nearshore  station  near Sturgeon Bay on the
western side of the Lake.  The first set of  data  was collected during
December 2, 1963 to April 21, 1964, for depths  of  10  and  30 m.  The
spectra were primarily noise  with  energy  concentrations indicated in
the long period oscillations around 200 hrs. The second set of data was
                                  171

-------
collected from April 20, 1964 to July 3, 196k at 22, 30, and 60 m.  The
speed spectra show a peaking of energy in the periods between 14 and 25
hr, with  little  elsewhere.  The three  most  significant peaks in the
velocity spectra are the first free oscillation  of Lake  Michigan, the
near-inertia!  period  coupled with  internal waves, and a long  period
oscillation near 100 hr.  The seiche  period  is near 8.7 hr at 60 m in
the Vx spectra and near  8.9 hr at 60 m in the Vy spectra.  Those peaks
near the inertial oscillation had a period of 17.4 hr at 22 m  and 16-7
hr  at  60  m for both Vx and Vy spectra.  A long period oscillation is
evident only in the Vy spectra and it is between 66 and 90 hr.

       Station 38 is an offshore  station in the northern basin of Lake
Michigan east of Sturgeon Bay and west of the  Lake's center.  The data
were gathered from December 2, 1963 to May 4, 1964 at 30 and 120 m. The
speed  spectra  showed a peak at the near-inertia! frequency of 17.4 hr
at 120 m.  The rest of the speed  spectra have  only noise, with energy
concentration in long period oscillations. Both of the velocity spectra
showed an  oscillation at 16.7 hr very clearly at the 120-m depth.  The
Vx spectrum had a significant peak at 66 hr.

       Station  39  is  in  the  middle  of the Lake west of Frankfort,
Michigan. During December 4, 1962 to March 21, 1963, the speed spectrum
data were collected for 90, 150 and 210 m. Large peaks are seen at 15-3
hr at 150 m and  20  hr  at   210 m; however,  these estimates are just
indications  of the periods due to the large number of zero speeds con-
tained in the data. The second set of data was collected between August
22, 1963 and November 6, 1963 at four depths of 22, 30, 120, and 180 m.
The speed  spectra  show broad peaks at 16.4 hr  and 22 m,  15.6 hr and
30 m.  The 15.3-hr peak at 120 m is very prominent and the 15.6-hr peak
at 180 m is also very sharp.  The Vx  and Vy spectra have near-inertia!
periods at 16.4 hr at 22 m, 16.7 hr at 120 m with a broader peak in the
Vy spectrum.  The energy  in  the  Vx spectral peak is slightly greater
than in the corresponding peaks in the Vy spectra.

       Station 40 is an offshore  station in the northern basin west of
Frankfort  and east of the Lake's center.   The data were gathered from
January 22, 1964 to April 19, 1964 at 10, 60, and 120 m.  The speed and
Vx spectra are mostly noise, but a period of 17.4 hr is clearly evident
in the Vy spectrum, Figure 6-3fc.

       Station 4l is an onshore station near the east shore of the Lake
near Frankfort.  The data  were  gathered  between  August 22, 1963 and
November 5, 1963,  at  four depths, 10, 15,  90,  and 120 m.  The speed
spectra show a period  of 15-3 hr at 10, 90, and 120 m;  and 18.7 hr at
15 m.  A large amount of  energy is indicated in periods between 30 and
50 hr. The Vx spectrum shows a broad peak at 10 m between 15.3 and 16.3
hr while the  Vy spectrum at this depth shows a l6.1-hr period.  The Vx
                                 172

-------
and Vy spectra at 90 and 120 m show a 15•3-hr  period.  A reliable peak
of 12.5 hr appears at 90 m in the Vy data, Figures 6-35, 6-36 and 6-37.

       Station 5!* is  located  in the  Straits of Mackinac between Lake
Michigan and Lake Huron. The data were recorded during the fall of 1963
from September 21* to November 30 at three depths; 10, 22, and 30 m. The
speed spectra  have two  principal peaks.  The period near the inertial
oscillation  is estimated to be 15.3 hr at  10 and 30 m and 16.1* hr  at
22 m.   Peaks at 28 hours at 10 and  30 meters and 29.6 hr  at 22 m are
interpreted as the half period of the  oscillation of Lake Michigan and
Lake Huron, computed to be 56 hr.  The spectra at the station are based
on current speed  measured by  the Savonius  rotor.  The rotor is omni-
directional  and  the  spectra  thus appear as the half-period.  The Vx
spectrum has four principal peaks.  The co-oscillation period  of 56 hr
is recorded for all depths. The diurnal period is estimated to be 21 hr
for the 10- and 22-m records and 21* hr by  the  30-m record.  The semi-
diurnal period is  estimated to be around 12 to 12.9 hr  at all depths.
The first mode  of Lake Michigan appeared at 8.8 hr in the 10-m record.
The Vy spectra are mostly  noise  and  have no prominent peaks, Figures
6-38, 6-39, and 6-1*0.

       Station 6l is located in the mouth of  Green Bay.  The data were
recorded during  the  fall  of 1963 from September 23 to November 29 at
three depths; 10,  22,  and  30 m.   The chief peak at this location is
around 12 hr which represents a combination of  energy  from  the first
mode of free  oscillation of Green Bay and the semi-diurnal oscillation
(Mortimer,  5*0,  a conclusion verified by  harmonic  analysis, Figures
6-41, 6-1*2 and 6-1*3.

                               Summary

       The data can be conveniently divided into two groups, the winter
data and the summer data.   The  stratification  of  the Lake plays the
dominant role in the summer data, but also affects the winter data when
a deep reverse thermocline is present.

       The winter data can be  divided  into  three  groups.  The first
group of data is that collected under an ice cover.   The  Lake,  espe-
cially the area around stations  18 and 20 during the winter of 1962 to
1963) was under ice.  Figure 6-15  ha8 winter spectrum  from station 18
during 1962-63 as an illustration of the  first  group  and station 20,
illustrates the  second group  using 1963-6!* winter data.  The inertial
oscillation presumed  due  to  the rotation  of the earth is evident at
both stations.  The second group is comprised of data of random oscill-
ations due to the turbulent nature of the Lake. There were no ice cover
or stratification evident at the time when noise spectra were collected.
                                   173

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The third group of data results when there is a reverse thenftocline and
the Internal wave oscillation  causes a peak near  the inertia! period.
Stations  33  and  39  «nov  an  inertial peak at great depths near the
thermocline with winter spectra froa station 38  in Figure 6-15 for the
third group.

       The summer data are  dominated  by  the  rotary currents largely
caused by  the  internal  waves.   The  first  free oscillation of Lake
Michigan is also readily evident along with some long  period  oscilla-
tions apparently due to long period meteorological disturbances. Figure
6-l6 shows a typical example of summer spectral data.

Monthly Histograms

       The monthly histograms provided the data for the net flow analy-
sis.  The data also provide the essential information on  total  flows,
mean direction, and speed variations at each station.  Zero values were
not used in the tabulation and spurious high speed values not consistent
with the station were dropped from the data.

       The prime value of the histograms  is  to  visually disclose the
distribution of speed and direction over a period of time large  enough
to mask the long period rotations. The 17-hour period accounts for only
2.5 percent of the total time during a month and the rotations are thus
effectively hidden.

       Where the internal wave is most conspicuous the histograms  show
little net movement  in  any  direction, Table 6-8.  In the winter most
stations show a to-and-fro movement if winds are variable, but are uni-
directional if winds are dominant from one quadrant.   Along the shore,
during winter  and  summer,  movements are usually binodal.  In general
currents  parallel the  axis  of  the  Lake.  The only major  exception
appears in the ridge area between Milwaukee and Muskegon.

       Speed profiles for currents are normally smooth, peaking  in the
vicinity of the average  speed  of  the station and decreasing out to a
maximum speed (Verber, 89).  Ninety histograms were examined and summer
speeds were normally greater than  winter  speeds  at depths from 10 to
60 m.  Below this depth, the winter speeds were greater.

       Station 6l, in the  channel  between Green Bay and Lake Michigan
had unusually low values for all three meters compared to other stations
in the Lake.  If such speeds had occurred at one level the rotor values
would have been suspect, but the speeds were uniform within the column.

       Station 5k, in the Straits of Mackinac, had the highest individ-
ual speeds, over 60 cm/sec,  in  the  Lake.  The average speed, near 20

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      TABLE 6-8




      HISTOGRAM




STATION 9, 15 METERS




  OCTOBER 1-17, 1963
   SPEED IN CM/SEC
ANGLE
0
30
60
90
120
150
180
210
240
2?0
300
330
TOTALS
4.5
11
9
15
11
11
7
4
3
8
11
10
15
114
13.5
27
30
35
35
29
39
34
39
43
U6
28
26
4ll
22.5
25
25
25
33
35
51
56
46
40
2k
16
28
4o4
31.5
13
2k
21
16
12
25
25
17
19
11
23
14
220
1*0.5
4
5
2
2
4
3
1
2
3
1
5
4
36
49.5
1
0
0
1
0
0
0
0
0
0
0
1
3
NUMBER
81
93
98
98
91
125
119
107
113
93
82
88
1188
FLOW
1603.5
1984.5
1872.0
1922.0
1786.5
2554.5
2515.5
2110.5
2227.5
1573.5
1701.0
1707.0

         175

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cm/sec, was not exceptionally greater than  for  stations 8 or 9 during
the summer.  In general,  speeds on the eastern  side of the Lake (near
the shore) averaged k to 5 cm/sec higher than the speeds on the western
side.  Stations near shore did not  show  unusually  higher speeds than
the offshore stations.

Six-Hour Averages

       Some of the most useful  data  programmed for analysis work were
the 6-hour averages.  Periodic functions in Lake Michigan  are  usually
18 hours or more and thus not completely  obscured  by  the   averages.
Similarly,  long-term trends can be readily displayed without a mass of
detail.  Daily  averaging (2k hours) produces spurious results from the
summer data because of  the  averaging  of the 18-hour inertial period.
The result is a fictitious 90-hour period.

       Phenomena  which occur over a 3-to-^-day period, such as current
speed responses  to winds, are readily  disclosed  by plotting (Verber,
89).  Table 6-9 illustrates 6-hour data from  one  station.  The summer
data include the average of 18  readings  where all data were valid and
12 readings for the winter period. If speeds go to zero, the vane read-
ing is  not included.  A continuous plot of the 6-hour averages, speeds
and direction, was made for some analysis work.   The  effect of rotary
currents,  produced  by  the  internal wave is readily disclosed by the
plots.

       Plotting of 6-hour average current speeds indicates that respon-
ses to wind energy can be traced from station  to  station and depth to
depth without difficulty.  Current speeds at a station have been traced
from the shore and across the Lake and for more than 200 km in a north-
south direction. Although current speeds show a direct response to wind
stress (within 2 hours),  the response to a change  in direction is not
well established in mid-lake.   The drogue study data included at least
three abrupt wind shifts, runs 3> 5> and 6.  The 6.1-m drogues were not
affected by a  wind  shift  on run 5, even after several hours.  It  is
believed that topography was the primary  influence  in maintaining the
direction. Wind shifts in run 3 indicated no shift in current direction
at 1.5 meters at the end of 1.25  hours.   The  study was terminated at
that point.  On run 6, the current shifted with the wind within an hour
whereas the 6.1-meter currents did not show any abrupt shift.

       Responses of current direction  change  to wind shifts are slow.
Within the Lake  proper one must  consider the previous wind regime, as
the force which must be changed, the newly applied force, and its areal
extent.  The  work by Ayers et al. (2), using a geometric series on the
winds is an attempt to uncover these relationships.
                                  176

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                              TABLE 6-9

                 LAKE MICHIGAN SIX-HOUR AVERAGE WINDS

                              STATION 54
0
Month
9

9

9

10

10

10

10

10

10

10

10

10

10

10

10

10

10

Day
26

28

30

2

4

6

8

10

12

Ik

16

18

20

22

24

26

28

Yr
63

63

63

63

63

63

63

63

63

63

63

63

63

63

63

63

63

An*
22
15
9
1
26
20
21
30
4
19
21
35
30
20
16
6
33
22
23
23
12
9
Ik
15
25
8
14
21
20
19
22
31
3k
0
Sp**
12
7
13
12
16
11
20
17
7
5
12
7
12
7
3
8
10
7
18
5
6
4
3
5
7
16
15
9
8
14
8
12
8
9
6
An
2k
22
11
36
33
21
23
3k
19
21
22
32
28
20
19
2
30
22
24
24
21
9
10
17
28
10
16
21
18
21
19
30
33
1
Sp
13
13
14
11
9
13
15
14
7
12
15
10
6
4
3
9
6
9
16
7
7
7
4
6
5
20
10
7
11
11
12
12
8
10
12
An
24
28
12
31
26
22
24
32
25
23
23
29
27
25
27
3
25
24
25
31
28
27
1
28
33
11
26
26
21
23
23
25
33
35
Sp
13
18
17
9
6
18
12
16
12
13
26
14
7
12
9
6
12
19
13
9
7
5
5
9
4
22
7
10
13
15
15
15
8
9
18
An
25
35
9
29
20
20
28
33
22
18
28
30
23
22
19
35
25
23
25
13
25
21
10
22
33
12
28
12
18
24
29
28
36
35
Sp
8
11
16
13
7
16
13
11
8
6
10
14
7
5
4
12
13
12
8
5
5
3
5
5
7
25
5
8
7
9
10
10
11
10
 *Angle in tens of degrees.
**Speed in cm/sec.
                                 177

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       Station 7 near  the shore,  and station 8,  approximately  3*4- km
east of station 7, were compared for responses to wind shifts. Winds at
station 8 were used as being representative for the area.

       Of the four wind shifts observed, which were due to frontal pas-
sages, station 7 responded  in  every  instance  as shown by the 6-hour
data.  Station 8, dominated by rotary currents,  continued  to  rotate,
with increased speeds, but the  residual  current did not change direc-
tion.

       Station 7 reacted to the wind shifts in 18 to 30 hours depending
on the speeds of the wind.  It is apparent from the 2-hour records that
the changes or response times occur much more quickly than the averages
indicate.

Two-Hour Envelopes

       The 2-hour maximum and Tn-tp-tiwift  values  show the great stability
in  water  movements.   No  great  changes  occur within short (2-hour)
periods of time and complete shifts usually  take  more  than 12 hours.
The rotary current,  approximately  17 to 18 hours,  usually represents
the greatest or  most rapid reversal  in direction for currents in mid-
lake.  Complete reversals in the upper layers may occur in 1 or 2 hours
near the shore, as indicated by the drogues. It may take up to 18 hours
for the entire column of water to reverse direction.

       The most significant use of the 2-hour  envelopes is  for visual
interpretation (see illustrations in Chapter 10). Problems of blurring,
extraneous high speeds, periodic changes, dally fluctuations, and other
features are seen instantly. Thirty centimeters (12 inches) of the com-
plete  printout  represents  5  days  which  include more than 300 data
points.

       The summer current data in mid-lake  (and some inshore stations)
are usually  dominated  by  the  internal  wave and exhibit some rotary
motion.  Stations 8 and 9,  where the internal waves exert their purest
influence, have shown  continuous rotary  motion for more than kO days'
duration.  Both direction and speed illustrate the undulating or rotary
form. Verber (90) indicates the presence of five types of flow normally
found in the Lake.  Straight  line flow is most prevalent in winter and
at selected areas in summer, such as nearshore flows and channels.  All
other types of flow in summer are some form  dominated  by the internal
waves.  Rotary motion in winter can be due to the deep internal wave on
the reverse thermocline or to true inertial motion.

       The visual display of the 2-hour envelopes makes them more valu-
able than the 6-hour envelopes.
                                  178

-------
Flow at Straits of Mackinac

       Station 54 is located in the  Straits  of  Mackinac, and current
meter records  are available for approximately a 1-month period — from
the last week in September through the month of October 1963.  The sta-
tion was first instrumented in December 1962, with intended recovery in
May 1963, but unfortunately those meters were lost.  Summarized results
from the October 1963 record are given in Table 6-11 and on Figure 6-44.

       Current through  the  Straits  reverses  approximately  every 26
hours, due to the Lake Michigan-Lake Huron 51-hour seiche.   The  nodal
point of the seiche  is  at  the Straits and here the currents would be
strongest.  Speeds in excess of 60 cm/sec are common in the record, and
speeds exceeding 30 cm/sec occurred 23 percent of the time.  Table 6-11
shows the average speeds during the 1-month record, at each of the three
depths where meters were  located  and  for  both eastward and westward
flow.

       For translating the velocity  readings into  volumetric rates of
flow, the cross sectional  area  of  the Straits was divided into three
parts and apportioned among the three current meters  at  station 54 in
the percentages  shown  in  Table 6-10.   The resulting calculated flow
rates are shown on Figure 6-44.  The net outflow shown  on the graph is
about 1,500 cubic meters per second for  the  period of record.  As the
graph also shows,  short-term  flow  rates  approaching  20  times this
magnitude occur both into and out of Lake Michigan.  Thus  the periodic
seiches provide  a mechanism for the exchange of large volumes of water
between Lakes Michigan and Huron.

Summary of Lake Currents

       The data from Lake Michigan  disclose  that a  simple pattern of
net circulation does not exist in summer,  but that one can be  identi-
fied in winter.

       Movements close to the shore  are  fairly stable  in both winter
and  summer  and  respond  to  the  winds prevailing over the Lake.  In
general, the shore currents move northward  on  both  sides of the Lake
except for periods during the late fall, winter, and early spring. Dur-
ing these periods  more  northerly  winds prevail.  The currents in the
western part of the Lake are noticeably slower than those in the eastern
part,  except  when northeasterly winds prevail.  Average speeds on the
western side of the Lake range from 5 to 10 cm/sec  while those on  the
eastern side range from 12 to 14 cm/sec.

       Inshore  and  offshore  currents  are  quite  separate  from one
another.  Offshore patterns are governed in the winter by long-term wind
                                   179

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                              TABLE 6-10

               CROSS SECTION OF THE STRAITS OF MACKHIAC
SECTION

Top

Mid

Lower
  DEPTH
IN METERS

   15

   12

   37


   6k
AREA IN
SQUARE METERS
68,560
2^,190
18,730
PERCENT
OF TOTAL
61.5
21.7
16.8
                             Total
         111,480
          100.
                              TABLE 6-11

              AVERAGE SPEED AND DIRECTION IN THE STRAITS
                          EASTWARD
                                       WESTWARD
SECTION

Top

Mid

Lower
   ANGLE

   276°

   291°

   271°
CM/SEC

20.05

20.80
ANGLE
120
 99*
   o
CM/SEC

20.66

16.58

13.71
                                  180

-------
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                                                                                        FIGURE  6-44

-------
movements and pressure patterns.  During the summer the  internal  wave
so overshadows all other features that the external effects are obscured
except  in  the  current  speeds.   The internal waves produce a rotary
motion in the currents with a  IT-  to  18-hour  period.   In  general,
epilimnion  and  hypolimnion flow are opposed in direction (l80° out of
phase).  The opposing phase relationship  applies  only  to  the rotary
motion and  not  to  the  net flows.  In a few instances certain layers
within the hypolimnion will not "be  a  perfect  180°  opposite  to  the
epilimnion. These cases occur when external pressures produce an oscil-
latory current rather than a spiral flow. Although the currents are out
of phase during part of the cycle, the  oscillatory  current  does  not
complete a full 3^0°.  This shift of flow can occur in  the  epilimnion
as well as the hypolimnion.  Net flows,  over a month period, may be in
the same direction from the surface to great  depths.   In  winter  the
vertical  profile  indicates  that extremely large masses of water will
react together and to 100 or more meters in depth.

       In the summer the net circulation in the  Lake  breaks down Into
cells which are largely controlled by standing internal waves.   As  it
takes time, after wind disturbance,  to build up standing oscillations,
and as a mixture of waves of differing nodality may  be  present,  each
decreasing in amplitude at a different rate, the boundaries of the cells
will not be rigidly fixed and the picture is likely to be  complex.  In
inshore waters, constraint and friction imposed by boundaries and shal-
low depth lead to a different current regime,  with  flow predominantly
parallel to the shore, and  internal waves are not so evident in  these
waters.
                                   182

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                              CHAPTER 7

                          TEMPERATURE STUDIES
Introduction

       Knowledge of temperatures within the  waters of  a lake,  and of
variations in water  temperature  with  respect to both time and place,
yields valuable  Insight into such phenomena as density stratification,
extent and effectiveness of mixing,  and consequent variations in water
quality.

       This section presents the results of temperature observations In
Lake Michigan, a review of and comparison with recorded previous studies
and the conclusions  which may  be drawn concerning temperature regimes
and their influence on water movement and mixing.

       Field observations of temperature changes in Lake Michigan began
in  September 1961,  and  continued  on  an  intermittent  basis  until
September 1963.  Temperature profiles were made  throughout the Lake at
the water quality sampling station sites  during cruises 1 to 8 and  10
through 18.   Bathythermograph (BT)  measurements were also made in the
deeper portions of the Lake during the  fall and winter of 1961-62 dur-
ing cruises 50 through 52.

                             Definitions

       Stratification occurs in a lake when its waters are divided into
layers having identifiable differences in temperature, density, or other
characteristics with rather sharply defined boundaries or zones of tran-
sition between layers. Thus, a lake in which the temperature was either
constant or varied uniformly from top to bottom would  not be thermally
stratified. A deep lake in the temperate zone usually stratifies during
the summer and may stratify during the winter. Very shallow lakes rare-
ly stratify, due to constant mixing from top to bottom by wind  action.
However, during prolonged calm periods in mid-summer, even shallow lakes
will stratify for  short periods of time.  A typically stratified  lake
is divided  into three thermal zones:  the top zone, called the epillm-
nion; the bottom zone, called the  hypollmnion,  and  a  zone  of rapid
temperature change called the thermocline.  The thermocline is normally
defined as  any  abrupt  change  in  temperature between two vertically
separated masses of water of different temperature.  There  may also be:
secondary thermoclines,  where more than one exists; the winter thermo-
cllnes,  where colder but less  dense water lies over warmer but denser
water; and pseudo or false thermoclines,  sometimes produced by unusual
local conditions.
                                   183

-------
       In Lake Michigan the epillmnion  varies from a few meters thick-
ness in late spring or early summer to over 6l meters in late fall. The
thermocline  normally is about 6 meters thick but can be over 15 meters
in thickness or as little as 1 meter  (during storm periods; see Figure
lO-l). The hypolimnion encompasses all the water belov the thermocline.

       An overturn is  a  descriptive  term denoting vertical mixing or
circulation from top to bottom of the entire lake. If the lake is shal-
low a complete overturn may occur.   Lakes  which are extremely deep or
sheltered  from  the  wind  may only experience a partial or incomplete
overturn. An overturn occurs when the lake is isothermal and, therefore,
of the same density.   According  to  Welch (92) the thermal resistance
under such  conditions is at a minimum and relatively light winds could
cause complete circulation.   Most lakes In the temperate  zone have an
overturn in the spring and fall.   In  Lake  Michigan  a  fan overturn
occurs in the southern basin when the Lake begins to cool, and is char-
acterized  by  the  sinking  and  mixing  of cold, dense water from the
surface,  displacing the warmer and lighter water below.   Cooling con-
tinues until the  Lake  reaches  the temperature of maximum density and
the water mass offers little resistance to mixing  from the wind energy
Imparted by late fall storms.  Figure 7-1 shows the temperature-density
curve for fresh water.   In the deeper northern basin of Lake Michigan,
the bottom portion of the Lake  remains permanently  at the temperature
of maximum density.  The temperature of maximum density of water varies
with pressure and therefore with depth,  being about 4"C at the surface
and decreasing about 0.06°C per 31 meters  of  depth  (see Eklund, 29).
This zone of constant  temperature  was found  to  extend from the 183-
meter  level  downward  during  the  period of observations.  The level
probably varies from year to year  depending  on  the  severity  of the
winter. A spring overturn occurs in the southern basin of Lake Michigan
when the surface water temperature rises  to ^°C and the denser surface
water sinks through the less dense layers below.  In the northern basin
there is also a partial overturn.

       A thermal bar or barrier,  as described by Rodgers (68),  occurs
in both spring and fall. This bar appears to inhibit or restrict mixing
between the nearshore and offshore waters during the few weeks it is in
existence. A sharply defined thermal barrier was found during the 1961-
1962 bathythermograph studies in the Milwaukee region. Records indicate
that the bar  or a condition similar to it may occur at any time of the
year.

Previous Studies

       Five important studies on the temperatures of Lake Michigan have
been published.  In addition,  hundreds of observations are being taken
every day at water  intakes by  the plant operators.  The bulk of these

-------
     1.00000-



     0.9 9 9 7 7 -



     0.9 9 9 5 4 -



>-   0.9993 I-
I-

eo
UJ
o
                               TEMPERATURE      °C

                01        4    6    8    »0    12    14    16    IS   20    22
                I   I   .   ,  I  i  1  .   I  i   I   i  I  .   I  i   I   i  I   i   1  i   I
     0.99908-
    0.99885-
     0.99862-
     0.9 9 8 3 9 -
     0.998 I 6-
     0.9979 3—'
    NOTE
    Welch, reference 10, page 350
                                               GREAT  LAKES  — ILLINOIS
                                                RIVER  BASINS PROJECT
                                             DENSITY OF FRESH WATER
                               185
    U S DEPARTMENT OF THF INTERIOR

FEDERAL WATER POLLUTION  CONTROL AuMlN
Greot Lokes Region           i~.hict.gi.' Ilir. 4


                         FIGURE  7 - I

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data nornally is  not  published  and  thus  not readily accessible for
general use.  Several thousands of observations have been made over the
past 15 to 20 years by research groups or other interested agencies for
application to other problems, such as biological studies.   The U.  8.
Mavy  Bade  observations  during World War II in its submarine tests in
Lake Michigan (Hough, Ho).   The  Great Lakes Research Institute of the
University of Michigan and the U. S.  Bureau of Commercial Fisheries at
Ann Arbor,  Michigan have collected and filed several thousands of tem-
perature soundings.

       The five principal  published  studies  on  Lake  Michigan  are:
Van Oosten (84),  Church  (l8, 19),  Millar  (52) and Ayers et al. (2).
Van Oosten carried out  most  of his vork in 1930-32 but the data  were
not published until 1960.  The work by Church (l8, 19) in the 19^0's is
probably the most comprehensive published to date,  covering all of the
seasons of the year.   Millar's  studies were for the surface waters of
the Lake and utilized the temperature recordings  from  ship's intakes.
The study does not  include  the mid-winter period.   Ayers et al. pre-
sented detailed temperature  profiles for various sections  of the Lake
during four synoptic cruises in the summer of 1955.   Van Oosten  lists
several of the minor published studies on temperature in Lake Michigan.
Moffett (53) has detailed an instance of upvelling on the east shore of
Lake Michigan;  and Mortimer (5^)  has assembled and interpreted summer
temperature records from 15 waterworks intakes.

       Although many studies of  temperature  have  been  made  in Lake
Michigan there  has  been  a  paucity of data for the winter period and
specifically from the deeper parts of the Lake.

Methods of Study

                             Instruments

       The investigation by  the Great Lakes-Illinois River Basins Pro-
ject utilized the instruments  discussed  below.  The  bathythermograph
(Figure 7-2)  was  invented  and first described by Spilhaus (73).  The
instrument was not generally  available  until the end of World War II,
and even then the cost was still prohibitive  for its general usage.  A
description of its operation and  capabilities  has  been  published by
Bralove (lU).  The most accurate of all  thermometers  is the reversing
thermometer, often called  a deep-sea thermometer.  A detailed descrip-
tion and specifications have been reported by Welch (92).  A hand ther-
mometer,  of the armored type,  is used for calibration of the BT.  The
temperature recorder, Figure 7-3>  developed  at the Woods Hole Oceano-
graphic Institution, has  been designed for long periods  of recording,
unattended, and at great depths (Feyling, 32).
                                  186

-------
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-------
     TIE RODS
     MERCURY SWITCH —
     CAM ADJUSTMENT KNOB
     (BACK SIDE)
     TIMING CLOCK 	
     TAKE UP ROLL
     PEN ARM
     PEN PRESSURE ADJUSTMENT

     PEN LIFTER	
      TEMPERATURE SENSING
      BULB
                                                        LIFTING PAD
                                                        (MAY BE USED ON BOTH ENDS)
       END CAP

       "0" RINGS


       PRESSURE CASE (ALUMINUM)
       RECORDER SWITCH
       CONTINUOUS OFF INTERVAL
                                                        SPINE


                                                        MOTOR CAM 8 SWITCH
       RELEASE  CATCH FOR SPOOL
       SHAFTS


       WAX-PLASTIC CHART PAPER


       SUPPLY ROLL


       TEMPERATURE ELEMENT


       HIGH-LOW TEMPERATURE STOP
                                                    	  BASE CAP
                                                            SCALE
                                                        0
                                                        LUJ
                                                                    41N
                                                                    IOCM.
MATERIAL
ALUMINUM a STAINLESS STEEL

FINISH
OXIDE FINISH 8 YELLOW EPOXY PAINT
ON ALUMINUM PARTS
 GREAT  LAKES   —  ILLINOIS
   RIVER  BASINS  PROJECT
TEMPERATURE RECORDER
                                   188
                                                U S DEPARTMENT OF THE INTERIOR
                                             FEDERAL WATER POLLUTION CONTROL ADMIN
                                             Gr.ol LuktsR.q.on           Ch,co«C,Mlm0,*

                                                                       FIGURE 7- 3

-------
       In general,  the  instruments have the following ranges of accu-
racy:

                              TABLE 7-1

                   DEGREE OF ACCURACY OF INSTRUMENTS

       INSTRUMENT                                  RANGE IN °C

       Band Thermometer                               - 1.0

       Thermometer Recorder                           ~ 0.25

       Bathythermograph                               - 0.1

       Reversing Thermometer                          i 0.01
       The BT is  useful  in  obtaining a complete temperature profile,
taking a few minutes of time,  in depths over 200 meters of water.  The
reversing thermometer can get accurate temperatures at  one depth  (such
as a sampling depth)  in a period of 3 "to ^ minutes.  A series of  these
instruments is frequently  used  on  a  single  line.   The temperature
recorder  can be placed at a specific depth and set to record the  tem-
perature every 20 or 30 minutes on a strip-chart for periods as long as
6 months.   Such recorders were used in conjunction with current meters
in the Great Lakes studies.

                       Bathythermograph Surveys

       Beginning in September 1961,  the  Project began intermittent BT
soundings on all cruises in the Lake.   The  last  continuous cruise to
collect BT  data was number 18 which ended in September 1963-  Approxi-
mately 1,300 BT records  were taken and read.  Figures 1-k to 7-27 show
the map locations and Table 7-2 gives an example of the data.

       Regular  lakewide  cruises  were  made  by  the Project from the
spring of 1962 through 1963.  These were identified as cruises 1 to 18,
see Table 7-3-   Since many temperature records were taken prior to the
regular  scheduled  cruises,  they  were  identified as 50, $!.» and 52.
Cruise 50 was principally in the south basin in 1961. Cruise 51 was all
in the deepest  portions of the northern basin and cruise 52 was in the
southern basin early in 1962. Special attention was given to the winter
of 1961-62 to determine if winter stratification existed in the Lake and
if so, to what depth.

       All data  were read at 3-meter (10 feet) intervals for the  first
31 meters and at  6-meter  intervals  (20 feet) to 6l meters.   From 6l
                                   189

-------
 s0' — GrttnBoy
   Fond Du Loc
            Port
   , .  «._ Washington
                                              uiMgon
                                             Grand Havin
>, 3. MILWAUK
          ffoot
                                          B«nton Harbor
                                                     GREAT  LAKES   —  ILLINOIS
                                                       RIVER  BASINS  PROJECT
                                                     LAKE   MICHIGAN
                                                              CRUISE NO. I
                                                          36 STATIONS SAMPLED
                                                             APRIL-MAY, 1962
                                                    U S DEPARTMENT OF THE INTERIOR
                                                FEOCRAL WATER POLLUTION CONTROL ADMIN
                                                8r'*of Lokts Region  .          Chkaao.Illinois
                                                                           FIGURE 7 ' 4

-------
   SCALE
0 5 10  20  SO MILES
ill   i   l
f l  i  T I
0 10 20 3040 KILOMETERS
                                                                      NORTH
                                                GREAT  LAKES  -  IL
                                                 RIVER  BASINS  PROJECT
LAKE   MICHIGAN
         CRUISE NO. 2
     29 STATIONS SAMPLED
         JUNE, 1962
                                              U S DEPARTMENT OF THE INTERIOR
                                           FEOCRAL WATER POL LUTON CONTROL ADIWN
                                           Gr*ot Lok*« Region           Chicago,Illinon
                             191
                            7-5

-------
    Kenosho
WIS. \ jo'
                                                                    i   i  i  i  i  i
                                                                  O 5 10 IS ao 25 3O KILOMETERS
                                                       SIBenton Harbor
                                                        GREAT  LAKES   -  ILLINOIS
                                                          RIVER  BASINS  PROJECT
                                     Michigan City
                                    R. —
LAKE   MICHIGAN
         CRUISE NO. 3
      31 STATIONS SAMPLED
          JULY. 1962
                                                       U.S DEPAHT«*€NT OF TH€ WTER4OK
                                                   FEOCRAL *WTER POLLUTION CONTROL AOMtN
                                                                             CMco«otHlmo«*
                                                                              FK5URE  7-6

-------
    U S DEPAi-  t
FEDERAL
Greot tunes.
jK  INTERIOR
• TL NTROL ADMI
                                        7 - 7

-------
    Shtboygon
    Kenosha
WIS. \so
ILL. j
   Woukegan
                                                                   0 5 IO 15 20 25 SO KILOMETERS

                                                         Benton Harbor  86o
                                                         GREAT  LAKES  -  ILLINOIS
                                                           RIVER  BASINS  PROJECT
                                                        LAKE   MICHIGAN
                                                                  CRUISE NO. 5
                                                             63 STATIONS SAMPLED
                                                                   OCT. 1962
                                                       U.S DEPARTMENT OF THE INTERIOR
                                                    FEDERAL WATER POLLUTION CONTROL ADMIN.
                                                    Great Lukts Region            Chicago,Illmoii
                                                                               FIGURE 7-8

-------
0 I  2 3 4 9 6 7 8 9 10 II 12 KILOMETERS
       GREAT  LAKES  -  ILLINOIS
        RIVER  BASINS  PROJECT
      LAKE   MICHIGAN
               CRUISE NO. 6
           32 STATIONS SAMPLED
             OCT.-NOV., 1962
     U.S DEPARTMENT OF THE INTERIOR
          WATER POL LUTON CONTROL AOMI*
 Grwt Luli«» fUgion
                            FK5URE 7-9

-------
            87°30
                                                 87,°I5
                                                                                           I
- ^!°30
                  3C-LE

                 3«5
                                    8 M'Lt
5 <  5  6 T  8  9 IO  II  i> KILOMETERS
                          196
                                               L  A  ".  r    v  i  c H i  c=
                                                          C?' '3E [JO •-.
                                                     nf- ~~A'IONS  SAM^LLD
                                                        jr T  r'CV.. ^-?
                                                           U S D£°«* "Mf1- T 0" '
                                                       FEOCBAL «*'ESPC_
                                                                                                  l
                                                                            M  /! DM N
                                                                                            7  10

-------
KENOSHA
        c
  WISCONSIN
                                    U S DEPARTMENT OF THE INTERIOR
                                 FEDERAL WATER POLLUTION CONTROL AOMIN
                                 Grtot Lch«» R«gion           Chicogo.tlMnoit
                     197
FtGURE 7-

-------
                   LWAUKEE
                                           GREAT  LAKES  - ILulNOIS
                                            RIVER  BASINS  PROJECT
                                          LAKE   MICHIGAN
                                                  CRUISE NO. 6
                                               86 STATIONS SAMPLED
                                                  OCT.-NOV.. 1962
i • i  r i—i—i—i—i—i—i
I  2  3 4  5  6  7 8  9 10 II 12 KILOMETERS
                                          U S DEPARTMENT OF THE INTERIOR
                                      FE.DCRAL WATEF POLLUTION CONTROL ADMIN
                                      Gr»o* Lukes Region          Chicago,Illinois
                         190
PK3URE 7-12

-------
    Kenosha
WIS. \so
ILL. j
   Woukeqan
                                                       GREAT  LAKES -   ILLINOIS
                                                        RIVER  BASINS  PROJECT
        IND.

MichiganCity
                                                      LAKE   MICHIGAN
                                                                CRUISE NO. 7
                                                            26 STATIONS SAMPLED
                                                              OCT.-NOV., 1962
                                                      U.S DEPARTMENT OF THE INTERIOR
                                                  FEDERAL WATER POLLUTtON CONTROL AOMIN
                                                  Grtot LuMs R«gion            Chicago,Illinois
                                                                             FK3URE 7- 13

-------
143

MILWAUKEE
 ILL.  J
   Waukeqan
                                                                     O  5  10 H 20 25 30 KILOMETERS
                                                         ^Benton Harbor  86o
                                                          GREAT  LAKES  -   ILLINOIS
                                                            RIVER  BASINS  PROJECT
                                                          LAKE   MICHIGAN
                                                                    CRUISE NO. 8
                                                               22 STATIONS SAMPLED
                                                                  NOV.-DEC.,  1962
                                                         U S DEPARTMENT CF THE INTERIOR
                                                     FEDERAL WATER POLLUTION CONTROL ADMIN
                                                     Grtat LoHii Region            Chicoqojlbnois
                                                                                       7-14

-------
201
                                      FIGURE  7-15

-------
46°
 30'—Gr««nBoy
43
                                                                                 NORTH
                                                                      NOTE
                                                                          S is for Special

                                                                  All special stations on cruise
                                                                     were "Spoil Banks"
                                                              30'  SI  Grand Haven
                                                                  32 Ludmgton
                                                                  S3 Manitowoc
                                                                  S4 Kewaunee
                                                                  S5 Frankfort
                                                                  S6 Menommee
                                                                  S7 Charlevoix
                                                                  S8 Sturgeon Bay
                                                                  S9 Mamstique


                                                                  45'
   4I°30'	
   SCALE
0 5 KD   20  30 MILES
111   1    l
I  II  T  r
0 » 20 30 40 KILOMETERS
                                                        GREAT   LAKES  —  ILLINOIS
                                                          RIVER   BASINS  PROJECT	

                                                       LAKE   MICHIGAN
                                                                  CRUISE  NO. II
                                                             49 STATIONS SAMPLED
                                                               MAY-JUNE, 1963

                                                       U.S DEPARTMENT OF THE INTERIOR
                                                   FEDERAL WATER POLLUTION CONTROL ADMIN.
                                                   Great Lakes Region             Chicago,Illinois
                                   202
                                                                                TK3URE 7-16

-------
  ,-^Port
 Washington
     \
    Kenosha
WIS. \,0-
ILL.
   Woukegan
                                                                         SCALE

                                                                    0   5  10      20 MILES

                                                                     I  I 'l  I1 I  |  |  I
                                                                    0  5  10  15 2O 25 5O KILOMETERS
                                                           Benton Harbor  86o
                                                           GRLAT  LAKES  -  ILUNOIS
                                                            RIVER  BASINS   PROJECT
MichigonCity
                                                          LAKE   MICHIGAN
                                                                   CRUISE NO. 12
                                                               110 STATIONS SAMPLED
                                                                  MAY-JUNE, 1963
                                                         US DEPARTMENT OF THE INTERIOR
                                                     FEDERAL WATER POLLUTION CONTROL AOMIN
                                                     Great Lakes Region            Chicago.lllinois
                                       205
                                                                                        7-17

-------
                    GREAT  LAKES  -  ILLINOIS
                     RIVER  BASINS   PROJECT
                   LAKE   MICHIGAN
                            CRUISE NO. 13
                        16 STATIONS SAMPLED
                             JUNE, 1963
                  US DEPARTMENT OF THE INTERIOR
               FEDERAL WATER POLLUTION CONTROL ADMIN
               0/Mt Lohts Region           Chicago,Illmoit
204
                                         FK3URE 7-18

-------
         -43°00-
      NOTE:
      Station No 14 not shown

      Latitude_42° 55' 20"
      Longitude_87° 5O1 15"
87°54'
                    SCALE
                                        I MILE
                      H	r
                          I KILOMETER
                                                        GREAT  LAKES  -  ILLINOIS
                                                          RIVER  BASINS  PROJECT
    LAKE    MICHIGAN
             CRUISE NO. 13
          25 STATIONS SAMPLED
              JUNE, 1963
    U S DEPARTMENT Of THE INTERIOR
FEDERAL HATER POLLUTION CONTROL ADM»N
Grtot Lu»t» R*gton           Chicoqo.Mkrtwf
                                     205
                           FIGURE  7-19

-------
             Mtnominte
so'-GreenBoy
                        80
                  ewaunee
                        77
                       76
                                                       Manistee
                                                        LSuding-
             hcboygan
Fond DuLoc
         Washington
     Milwaukee
                                         GREAT LAKES -  ILLINOIS
                                          RIVER BASINS PROJECT
             Racine
              30 MILES
                                        LAKE  MICHIGAN
                                               CRUISE NO. 14
                                            I03 STATIONS SAMPLED
                                               JUNE, I963
   *   i   i   i
0   10   20  SO  4O KILOMETERS
                                        U S DEPAHTMENT OF THE INTERIOR
                                     FEDERAL WATER POLLUTION CONTROL AOMIN
                                        Lo»«« Rtflion         Chicago,
                                                             7-20

-------
PlGURt

-------
7-22

-------
Manitttf
     utkegon
   Grand Hovtn
    South
    Hovtn
                     GREAT LAKES  -  ILLINOIS
                      RIVER BASINS  PROJECT
                    LAKE   MICHIGAN
                           CRUISE NO. 17
                         114 STATIONS SAMPLED
                         AUG.-SEPT.-OCT.. 1963
Benton Harbor
                    U.S.DEWHT*ttNT OF THE IHTERIO*
                 FC£CBAL WCTERPOLLUTION CONTROL AOMIN
                 firMt LokMfooion         Cfclcooo.tllinei*
                                       FIGURE 7-23

-------
210
                                    FIGURE 7-24

-------
   Green Bay
   Sheboyqan
 Milwaukee
CHICAGO
                                                            I 9 6

                                                       LAKE MICHIGAN
                                                                   40 Kilometers
                                                      GREAT LAKES  -  ILLINOIS
                                                       RIVER BASINS  PROJECT
                                                       STATION   LOCATIONS
                                                             CRUISE  50
                                                     U.S.DEPARTMENT OF THE INTERIOR

                                                 FEDERAL WATER POLLUTION CONTROL ADMIN.
                                                 Great Lakes Region           Chicago,Illinois
                                    211
                                                                           FIGURE  7-25

-------
212
                                      FIGURE 7 -26

-------
   Green
Mi Iwoukee
                                               I - 25-62
                                               2- 20-62
                                               6-14 - 62
                                               8-17 - 62
                                                                  40 Kilometers
                                      Bentort
                                       Horbor
 CHICAGO
     GREAT  LAKES  - ILLINOIS
      RIVER  BASINS  PROJECT
                                                     STATION  LOCATIONS
                                                           CRUISE  52
    US DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL ADMIN.
Great Lakes Region           Chicago,Illinois
                                 213
                         FV3URE  7 - 27

-------
                         TABLE 7-2

            TEMPERATURE DATA AND STATION LOCATION

            CRUISE 001                  YEAR 1962
       DEPTH                                   STATION NUMBERS
FEET
000
010
020
030
040
050
060
070
080
090
100
120
140
160
180
200
300
400
500
600
700
800
MfcL'JSKS
000
003
006
009
012
015
018
021
024
028
031
037
043
049
055
061
092
122
153
183
214
244
                                             002             003
                                                  (Temp., °C)

                                            03.5            06.5
                                            03-5            06.5
                                            03.5            06.5
                                            03-5            06.5
                                            03-5            06.5

                                            03.4            06.5
                                            03.4            06.5
                                            03.4            06.5
                                            03.4
                                            03.4

                                            03.4
                                            03-4
                                            03.4
                                            03-4
                                            03.4
TIME                                         1347            0917
DATE                                         0424            0425
SURFACE TEMP.                                03              06
TOTAL DEPTH                                  195             070
AVERAGE TEMP.                                3-4             6.5
                              214

-------
                    TABLE 7-2 (Continued)

            TEMPERATURE DATA AND STATION LOCATION
CRUISE

  001
  001
  001
  001
  001

  001
  001
  001
  001
  001

  001
  001
  001
  001
  001

  001
  001
  001
  001
  001

  001
  001
  001
  001
  001

  001
  001
  001
  001
  001

  001
  001
  001
  001
  001

  001
STATION

  001
  002
  003
  004
  005

  006
  007
  008
  009
  010

  Oil
  012
  013
  oik
  015

  016
  017
  018
  019
  020

  021
  022
  023
  024
  025

  026
  027
  028
  029
  030

  031
  032
  033
  034
  035

  036
LATITUDE

 4244oo
 1*22300
 420000
 420100
 414600

 414600
 420000
 422300
 422300
 424400

 424400
 424400
 430800
 430800
 433600

 433600
 440500
 440500
 440500
 443200

 442800
 444500
 444700
 444300
 444100

 443900
 442500
 442300
 443450
 442100

 440500
 440500
 433600
 430800
 430800

 430300
LONGITUDE

  861500
  863500
  863800
  865920
  870000

  872000
  871900
  872500
  870000
  872300

  870000
  863500
  870000
  872500
  874400

  872200
  873400
  872000
  870000
  872700

  870000
  870000
  871400
  864400
  863000

  861700
  864000
  863200
  861840
  862000

  863300
  864400
  863300
  863500
  861900

  862410
                             215

-------
                           TABLE 7-3

                       SCHEDULE OF CRUISES
CRUISE
50
T!
It
II
II
II
STATIONS
SAMPLED
106
VESSEL
PHS-19'
USCG-261
USCG-Woodbine
USCG-40'
USCG-36'
USCG-641
DATES
9/27/61, 10/6/61
10/11/61
10/21/61
10/24/61, 11/3/61,
11/8/61, 11/15/61,
11/21/61
11/29/61
12/21/61
OPERATING
AREA*
1
1
1
1
1
2
51       17     R/V Kaho, USCG-Mesquite

52       18     USCG-641
1
2
3
36
29
31
R/V Cisco
R/V Cisco
R/V Cisco
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
69
63
215
26
22

70
40
109
4l
105
123
22
114
51
                R/V Cisco
                R/V Cisco
                R/V Fitzgerald
                R/V Kaho
                R/V Kaho

                THIS NUMBER  NOT USED
                T-509
                R/V Cisco
                T-509
                T-509

                T-509
                T-509
                T-509
                T-509 Intermittent
                T-509
3/1/62, 3/20-22/62      2
4/14/62, 4/26/62
1/25/62, 2/20/62,       1
8/17/62, 6/14/62
4/24-5/7/62             1,  3
6/5-18/62               2,  3
7/17-30/62              l,  3

8/29-9/9/62             1,  3
10/10-22/62             1
10/18-11/30/62          1,  3
10/28-11/7/62           1
11/28-12/6/62           1
5/8-23/63               3
5/23-6/3/63             2, 3
5/22-6/9/63             3
6/9-6/12/63             3

6/13-6/25/63            3
6/26-7/12/63            2
7/15-7/26/63            2
8/8/63-10/8/63          1, 3
8/20-9/19/63            3
                                           *1   South Basin
                                             2   North Basin
                                             3   Shore or Harbor
                                216

-------
meters to  the  bottom  the  data were read at 30-meter intervals.  The
date, time, surface temperature  (using a  hand thermometer),  and total
depth were recorded.  On many cruises two or more FT casts were made at
the station.  In general, a cast was made prior to sampling the station
and after all sampling was completed.

                      Temperature Recorder Data

       Temperature recorder data were  collected  at all  current meter
stations in Lake  Michigan, Figure 7-28.  Approximately 2 million hours
of data have been  collected.   The  purpose  of  the  recorders was to
ascertain the relative position of the thermocline with  respect to the
current meter.

Results - BT Surveys

                              Fall, 1961

       Studies during the  fall of 19&L were made  only in the southern
basin.  This period  includes  data  from  the latter part of September
through December.  The Inshore areas  with  depths  to 20  meters  were
nearly isothermal, with surface temperatures of 15.5°C and still 15.0°C
at 20 meters.  The thermocline appeared sharply defined at depths up to
24 meters and less distinct at depths  of 47  meters or more.  With the
advance of colder  weather,  the thermocline  receded to greater depths
and disappeared completely between November 16 and 20.

                             Winter, 196l

       It is difficult to define the true winter  period,  as a thermo-
cline usually exists into late  fall.  The winter period, as classified
in this report, is the period  from fall  isothermal  conditions to the
formation of a thermocline in early spring.   Surface temperatures  are
usually near 7«0°C or lower in the fall and 6.0° to 7«0°C in the spring.
The onset of true winter  isothermal  conditions is preceded by unusual
thermal characteristics.

       Records taken in November 196! (Cruise 50) illustrate these con-
ditions.  Stations 48, 55, and 56 clearly indicate colder heavier water
overlying warmer lighter water.  This may be accounted for by hystersis
in the  instrument, but both the up and down traces were identical.  It
is more probable that,  as  the  water  cools toward the temperature of
maximum  density  during  calm  periods,  the  mixing process is slowed
because the differences in density are very small.  During  storm peri-
ods, with a great amount of turbulence in the water, the mixing process
is accelerated.
                                  217

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             ES C AN A • A
 G * e E
  MAN
MILWAUKEE
 CH i C.AGO
                                                               SCALE
                                                                       40 Kilometers
                                           BENTON  HARBOR
                                                     GREAT  LAKES  -  ILLINOIS
                                                       RIVER  BASINS  PROJECT
                                                          LAKE MICHIGAN

                                                  TEMPERATURE R£CORDER LOCATIONS
    U.S.DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL ADMIN.
Great  LaKes Region        Chicago.lllinois

-------
       The mean temperature in the southern Basic decreased by a  little
over 2°C between  November 29  and  December 21  and had fallen another
1.5°C by January 25-

       By February 20 (Cruise 52) the  low aid-winter  temperatures  had
been reached  which,  in the deeper parts of the southern Basin down to
150 meters, were characterized by uniformity,  from 2.0° to 2.3°C, from
top to bottom indicating complete mixing. There is no doubt that  mixing
from top to bottom  occurs  throughout  the entire winter period  during
every storm.  The inshore area had an ice cover  extending  out in some
locations to nearly 1.6 km.  Pack ice extended over  16  km   (lO  miles)
from shore.

       A thermal bar or barrier was found on January 25 and February 20.
Th-? inshore water,  out  to  nearly  16  km (deptn 42 meters) vas at or
slightly less than 0.01°C.  The adjacent  water  was  nearly  2 degrees
warmer  and  under the cold upper layers.  The barrier was very sharply
nefined and from all appearances looked like a winter thermocline,   but
was actually part of a thermal bar. The bar existed, in this  case, when
all temperatures were several degrees less than the temperature of nax-
•- m density.  A bar when temperatures are less than  4.0°C is  typical
during the entire winter period.

       The southern basin was nearly isothermal  for the entire winter.
'.'he northern basin had a true  winter  thermocline  for  the  months of
March and April 19^2.  Ti-uise 51 shove the changes observed in the deep
nole of the Lake.  Ots'rvations on Marcn 22, 1962 between 1315 and 1920
nours indicate that a large internal  wave may have occurred.  Again on
Aoril >k and April 26 -han^es in the thermocline nr-curred.  On April 14
there was an 18-meter change but on April 26  the change was  40 meters.
Thr wave period of th • venter thermocline was not r.ecisely determined ,
hut it is probably close to those found in midsummer.
       Although a tl er n*  line is indicative  of sv.r tt : :' teat ion,
1.0 the bottom  in  t.,e  aeep hole probably  occurre-; during  the period
between  the  summer and winter thermocline.  With a theraocline a-1,,  the
380-meter depth and teiT, eratures below maximum den^iiy in the ujper  IhO
 cte.-s,  the  evidence  for mi: ing to tnis depth is evident.   Th^ data
indicate that  the dst'., of mixing is a direct function of tne density.
-Ten isothermal  tempe-ai.ures (relatively speaking)  occur between 3.5°
?-nd 4.5°C,  mixing might occur in Lake Michigan fron top to bottom dur-
ing every storm.  It is also possible, if a winter 1 hermocline does  not
exist,  that  the  temperature range for mixing may be 1 or  2  degrees
• reater.
                                   219

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                             Spring, 1962

       Cruise 1 covered two-thirds of  Lake Michigan in  late April and
early May 1962.  Nearshore  temperatures  were as much  as 7.0°C higher
than mid-lake.  In general, the deep water stations of both basins were
nearly the same, ranging from 1.7° to about 3.5°C. Some inshore regions
already had definite  thermoclines established and surface temperatures
were up to 9.0°C.  Cruise 2 in early  June covered the  eastern and far
northern third of the Lake and Green Bay. The practice of taking a tem-
perature reading before and after station  sampling was  begun  on this
cruise.  Normally,  the two readings are  about 1 hour apart.  The ship
had some drift, but for all practical purposes it was in the same water
mass for both soundings. In most areas a thermocline existed except for
the deepest portions of the Lake. Surface temperatures ranged from 5.4°
to 10.6°C on June 5 and 6 and from 6-5° to 18.5°C on June 15 and 16.

       The practice of taking two bathythermograph casts disclosed what
may be called  short  period  internal  waves.  In a 1^-hour period the
temperature changed 1.6°C at station 2, depth 6 meters.  Less  dramatic
but similar changes occurred at other stations.

       The thermocline begins its initial formation in the shallow water
and works its way  outward  toward  the  center of the Lake as  warming
begins.  During  this process there is a  "dome" of  cold  water in the
central portions of  the Lake, and this has been  cited as evidence for
clockwise circulation (18).  Actually, such a "dome" will  occur  every
spring regardless of the direction of flow.   The  so-called  "dome" is
merely  a  result  of the physical method by which a lake warms.  Since
this process is reversed in fall,  the  Lake  is in a steady transition
from the shallow to deep water throughout the year.  Clearly,  for con-
tinental  lakes  such  as  Michigan,  gross  thermal  changes  are poor
indicators of water movement except for the  brief  period  during  the
month of peak solar heating.

                        Summer and Fall, 1962

       Cruises  2,  4, 5, 6, 7, and 8 covered only the southern half of
the Lake.  Cruise 3 reached a small part of the northern basin. Cruises
k and 5 were  limited to 20 miles from shore, but were very intensively
covered.  The thermocline  was  well established in July.  The mid-lake
temperatures in the southern basin were several degrees warmer than com-
parable temperatures in the northern basin.  The top of the thermocline
varied considerably from one station to another. These variations prob-
ably resulted  from  BT casts  during the progress of an internal wave.
The maximum temperatures were reached in mid-August and early September
after  which  the  Lake  began to cool slowly.  A thermocline was still
found in mid-November,  C6-138  and 157  at 55 meters and on December 2
and 3, C8-16, 18, and 19. No records were taken by the BT in the winter
of 1962-63.  Data were collected by use of thermographs.
                                   220

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                             Spring, 1963

       Cruises 10, 11, and 12 were made in  May and June.  By this time
the thermocline was already established  and  surface temperatures were
around 12.0OC and, in the very shallow areas, up to 23.0°C. Temperatures
in the northern basin in May were  nearly  20 degrees  colder than some
areas in the south.  The remnant of a winter thermocline was still evi-
dent, during Cruise 11 at the 214-meter depth.  During a cool spring it
is very likely  that  a winter  thermocline can remain until June.  The
great diversity of temperatures occurring during this period illustrates
the slowness of mixing and movement that occurs in a large lake.

                             Summer, 1963

       Cruises  13 to 18 cover the summer of 1963.  Temperatures in the
northern basin were lower than  those observed in the southern basin in
the previous year.  Shore temperatures range up to 25-0°C (C15-123) and
as high as  21.6°C (C16-8) for the deeper waters.  Maximum temperatures
again occurred in late August and early September. This type of heating
and then cooling appears to be the normal trend for the Lake.

                              Discussion

       Bathythermograph records  from  196!  through 1963 have revealed
several previously unknown features about the thermal  distribution and
the mixing rates in Lake Michigan.

       Normally, southern Lake Michigan has two well defined temperature
regimes:  the period of summer stratification which begins  in late May
and lasts through November and  occasionally  into  December,  and  the
nearly isothermal  period  of constant mixing.  The southern basin does
not stratify in winter. Temperatures as low as 2.3°C from top to bottom
indicate  complete  cooling  and probably mK-giiig throughout the winter-
spring period. Summer stratification begins at the edges of the Lake as
early as March and progresses  outward and the basin becomes completely
stratified by late May.

       The northern  basin  of  the  Lake  undergoes  three temperature
regimes. The summer regime does not become completely established until
late June and sometimes  early  July.  Likewise, the thermocline can be
found as late as December.  The  winter  isothermal  (mixing) period is
very  brief for the  deeper parts of the basin, lasting only one or two
weeks in the early winter and  again in  late spring.  The remainder of
the winter period, the  basin has a winter-type or reverse thermocline.
This  thermocline  is  deep,  forming  at  the 120- to 180-meter depth.
Although mixing  can occur from top to bottom for brief periods in late
winter  and  early  fall  the  bottom  part of the basin becomes sealed
                                  221

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against active mixing for 11 months of the year. The total depth of the
Lake and the depth of the thermocline in succeeding years indicate that
a winter-type thermocline would normally occur every year.

       The thermal barrier or bar appears to be a normal feature of the
Lake.  Recent work  by Rodgers (68)  in Lake foron disclosed the effec-
tiveness of this bar in preventing a free interchange between the shore
and offshore waters during  the winter  period.  Observations Indicated
that the bar forms when one zone is warmer than the temperature of max-
imum density  and the other zone is colder.  Records from Lake Michigan
revealed two water masses, lying side by side with nearly a 2°C temper-
ature difference  and  both  below  the temperature of «**••! mm density.
Even in midsummer the shore waters maintain a higher temperature differ-
ential of 5°C or more than the  offshore waters.  The summer separation
of the two zones, in terms of distance,  is not as narked as the winter
period.  Chemical studies do indicate, however, that there is a differ-
ence between nearshore and offshore  waters  in  the summer, similar to
those Rodgers found in Lake Boron.

       The bars described by Rodgers (68) appear  to be maintained by a
convergence mechanism operating at the  Junction  between  the  inshore
water mass, usually at temperatures above, and the  offshore  waters at
temperatures below, that of may-iim™ density.  It is suggested, however,
that other factors — for instance, topography and the effective  depth
of mixing ~ are principally responsible  for maintaining  a barrier to
offshore mixing.

       By itself, topography exerts a powerful  influence on the orien-
tation of water movements.  Because  water tends to follow the contours
of the Lake bottom, thus paralleling the shore,  there is little inter-
change with the main body of the Lake, which can move in any direction.
A pollutant discharged near the shore thus tends  to remain  inshore by
the very nature of the bottom topography and shoreline orientation. For
similar  reasons changes in temperature can result in a thermal bar and
tend to keep the two water masses separated.  The shore zone due to its
shallowness  and smaller volume, heats more rapidly in summer and cools
more  quickly  in winter.  On this basis, a type of thermal bar appears
to exist most of the year. The relative resistance to mixing appears to
be related  to the temperature differential and to the amount of turbu-
lence in the system. An onshore wind generating large waves may produce
mixing by forcing some of the shore water into the deeper layers of the
Lake  along the bottom.  An offshore wind produces the opposite effect,
tending to move  the inshore surface  waters out  into the main body of
the Lake.  The point at which the bottom  topography  does  not exert a
controlling  force  on the water movement is not precisely defined.  In
general, in summer it is between the 7- and 10-meter  contour  in  Lake
Michigan, which corresponds to the zone where waves begin to "feel" the
bottom.  The depth  may  be  somewhat  greater  in  winter when density

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differences between the upper and lower  layers are at a minimum.  Wind
mixing also is a  major factor in the width of the zone.  This is prob-
ably aore evident in early winter than in summer because of the lack of
resistance to mixing, and a well developed thermal bar may not be found.

Results - Temperature Recorder Data

       Thermographs obtained in  the winter of  1962 through the summer
of 1964 permit a much more complete interpretation of the thermal regime
than was  previously  possible.  Figure 7-29 shows the analog record of
temperature at station k for the depths  10 and 15 meters.   From March
31, 1963 until  May 2k, 1963  the  temperature  spread  between the two
levels was not discernible even though the column was gradually warming.
Both cooling and  warming affected the two levels at the same time.  To
distinguish between the two traces prior to the formation of the therm-
ocline, a constant of 0.2°C was  added  to  the 10-meter  trace until a
definite temperature separation was established. Station 1 at 10 meters
was added to show  the period  of  the thermal bar between the two sta-
tions.   From April 19 to May Ik, or nearly one month, the two stations
were on opposite  sides of the temperature of maximum density, although
this is probably not necessary to maintain the barrier.

       The actual formation of the thermocline  began  on May 23 and 2k
when the mean  daily  temperature began to rise and the wind shifted to
the east and southeast.  The thermocline appears to begin its formation
after the  temperature  of  one layer is near 5-0°C, the temperature at
vhich the density begins to decrease rapidly  with  increasing tempera-
ture.  Once two layers separate and the  upper  layer  warms,   thereby
increasing the density difference, the thermocline becomes firmly estab-
lished.   The  temperature  spread increased between the two levels and
except for rare occurrences the temperatures remained  apart until late
fall.  Temperatures taken  in  deep  water  on  the BT surveys compared
favorably with the thermograph for station k at the 15-meter depth. The
thermocline begins to decay in late September after the period of maxi-
mum heating.  The  decay  is  observed  as a so-called deepening of the
thermocline.  As the lake waters cool and the water temperatures in the
epilimnion approach those in the hypolimnion, a smaller amount of energy
is required to produce complete mixing between the layers.

                            Internal Waves

       Since the summer of 19&2, the Project has found  internal  waves
on the thermocline without exception, both summer and winter.  The per-
sistence of the internal wave in the summer was not clearly  identified
previously although its nature and importance were predicted (5*0- Fig-
ure 7-30 shows the persistence of those waves.

       Records appear to indicate that the internal waves, with a peri-
od near the inertial period, are standing waves.  Precise timing of the
                                   223

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FIGURE 7-29

-------
X
O
UJ
                    CVj   O   00   ID   J   c\j   O
                         3QVW9IJ.N30   S33H93a
CO

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-1 O
- tr
  CL

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CO?
UJ (/)
* <
< 03
_l
  £E
                                                        O
                                                                CO
                                                                UJ
tK
UJ
    to
    cr
    UJ
    i-
    UJ
                                                                    in

                                                                     i
                                                                    en
                                                                    5
Q
4

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£T
t-
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                                                                           < a:
                                                                           *  •>
         to  
-------
records shows that the temperature oscillations at stations 8, 9, and 10
(mid-lake) usually vary at the same time  rate  "but  not necessarily in
phase  (see  Chapter  10).   The  temperatures at the edges of the Lake
reflect the severe changes, with temperature oscillations up to 12°C in
3 hours.  These severe changes illustrate both the  upwelling and down-
welling characteristics  along  the  shore.  Although large temperature
changes  are  associated  with  the  mid-lake oscillations, they rarely
exceed 10°C in 16 hours.

       Stations 12 and 11 on opposite sides  of the  Lake indicate that
the internal waves are occasionally also in phase.

       A spectral analysis was run on seven  sets  of  temperature data
for 1963:  Figures 7-31, 7-32, and 7-33.   These are on  a  common fre-
quency scale and are based on 750 to 2,600 hourly temperatures  read to
the nearest 0.1°C during the months of July  through October 1963.  The
time span covered is as shown  for each individual station.  Station 11
had only 750 readings whereas the other stations had in excess of 1,600
readings.

       To make the data compatible with  recent  spectra  run  on water
level data in Lake Michigan by Mortimer (55)> similar methods of analy-
sis were employed.  The  methods of Blackman  and Tukey (10) were used.
A power spectrum was run on each set of  data with 200  lags.  The fre-
quency scale  is  linear,  from  0 to 12  cycles per day.  The abscissa
scale is amplitude squared per unit of frequency  using an increment of
one scale  for  the  base  of  another  spectrum.  The use of envelopes
permits an overlap of the data. Where the logarithmic scale becomes the
base of a new spectrum, a double line is shown.  The degrees of freedom
for each spectrum  vary  between l6 and 22  except for station 11 which
had  the  short record.  The corresponding 95 percent confidence limits
are shown on the individual figures.

       Figure 7-31 shows  the  spectra  for  stations  31 ancL U-l on the
eastern side of the Lake.  At  first  glance,  there appears to be very
little  similarity  between  the  two spectra.  Station 14-1 shows a pro-
nounced peak in the 16- to 18-hour range whereas  station  31  does not
show such a  sharp peak.  The analog trace of the temperature record of
station  31  indicates that at the station depth shown the meter was in
the epilimnion for  longer time periods than station kl.  This may par-
tially account for the smaller peak at this period.

       The spectrum for station 31 shows a distinct peak at the diurnal,
and a smaller one,  of  doubtful statistical significance, at the semi-
diurnal period. These peaks are not present in any of the other spectra
presented, and  this indicates that internal tides are not generated or
at least are of minor importance. This is in contrast to the spectra of
                                  226

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Scale
STA 41
     I03
     10'
  o
  o
     10'
     IOU
     icr
            24
            24
             I
 I
 12
                                 4.9
                                           3.4
                                                          10
                                   27   2.4
                                                   12
                                                               22
                                LAKE   MICHIGAN
                                    LOCATION MAP
                          STATION  31, DEPTH 22m

                                    AUG. - OCT.
                                          95%

                                      Confidence

                                        Limits
                  STATION 41,  DEPTH 22m

                        AUG - OCT
                                                        Scale

                                                        STA  31
                                                                       I02
                                                     10'
                                                     10"
                    HOURS
12
 I
8
I
6
I
 49
_J	
          4
              CYCLES  /   DAY
                                   GREAT  LAKES  — ILLINOIS
                                     RIVER  BASJNS PROJECT
SPECTRA  OF TEMPERATURE

    RECORDS  - 1963
                                                   U S OEPARTMf rjT Of THF IIMT tP.OP

                                               rFOERA, WATER POL L UTION CONTROL A.-WiN
                                                                          ,GURE  7-

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Scale
STA II
    10"   -
•o
a
O
o
    10"   -
    10'   -
    10°   -
                                       MICHIGAN
                                           STATION 8, DEPTH 30m
                              STATION 8, DEPTH 22m
                                  AUG.-SEPT.
    95%'
Confidence'
  Limits
                                     ,  DEPTH 15m
                                        AUG -SEPT.
                                                                    -   10
                                                                   12
                     Scale
                    STA. 8
                     22m
                    3
                                                                    -   10'
               -  10'
              -  10"
              CYCLE  /  DAY
                                                    GREAT  LAKES  — ILLINOIS
                                                      RIVER  BASINS  PROJECT
                                                 SPECTRA  OF  TEMPERATURE
                                                       RECORDS-1963
                                                   I, S Of i-ARTMENT OF THF INTERIOR
                                               FFDERAL WATER POLLUTION CONTROL  AuMlN
                                               Great Lotoes Region            ^rucojoli.nos
                                  228
                     >GUPE 7-32

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Scale
STA.4
    10'
    10'
I 0"  -
•o
QL
O
    10-'  -
    10-2 -
                                      MICHIGAN
                                   LOCATION  MAP
                                      STATION  20,  DEPTH 30m
                                            JUL -OCT.
    95%
Conf i dence
  Limits
                            STATION 4,  DEPTH  15m
                                   MAR. - JUL
                       Scale
                      STA  20
                                                                 -  \0'
                  -  10'
                  _  IOU
                                                                 -  10"
                                                                 12
                                                  GREAT  LAKES  —  ILLINOIS
                                                   RIVER BASINS PROJECT

                                                 SPECTRA  OF TEMPERATURE
                                                     RECORDS -  1963
               CYCLE  /DAY
                                                 U 3 DEPARTMENT OF THE iN'EHm
                                             FEDERAL WATER POLLUTION CONTROL
                                             Great Lakes Region           ~ >;.' ;
                                229
                              7-33

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surface water levels presented by Mortimer (55) In which tides, partic-
ularly the semidiurnal components, are conspicuous. A small peak at 105
hours also shows at station 11, Figure 7-32. Although the peak is small,
it may be quite significant as  it also  appears in the current spectra
and perhaps corresponds to the passage of high and low pressure systems
over the Lake.

       Figure 7-33 shows the spectra  for  stations  k and 20 which are
more mid-lake than stations 31 and ki. The 16- to 18-hour internal wave
overshadows by far all other peaks.

       Figure 7-32, stations 8 and 11, also shows the long period inter-
nal wave.  The several peaks in the 13- to 18-hour range may be indica-
tors of the several types of wave phenomena found on the thermocline.

       The six spectra  presented  here  may  also contain peaks corre-
sponding to the first five nodes of the longitudinal surface seiche but,
if so, these are buried below the noise level of the spectrum. The long
period  internal  wave  system,  near  16- to 18-hours,  dominates most
records. Storm inputs excite this particular frequency and maintain the
internal wave.  The dissipation of energy  in the formation of internal
waves assists in maintaining the thermocline.

                            Analog Records

       Figure 7-31*- shows the analog record at station 8 for 10, 15, 22,
and 30 meters.  The records  were  exceptional in that they were within
0.2 percent difference  in timing from one record to  another  for over
1,800 hours.  The persistence of a regular temperature wave of close to
17 hours' period is evident and, where the phase relations can be reli-
ably determined,  appears to  be in phase at ftll depths.  As is pointed
out later in Chapter 10, this indicates an internal  wave  of the first
vertical node  appropriate to a two-layered system.  The interval occu-
pied by the first 15 waves in  Figure 7-3**-  indicates a mean  period of
16.9 hours which corresponds to the highest peak  in  the  Figure  7-32
spectrum.  For the kind of period presented in Figure 7-3^ it may often
be more precise to  determine  the  period  visually  than  by spectral
analysis.

Summary

       Temperature  records taken during the winter of 1961 through the
summer of 196k indicate that the following conditions occur:

       1.  Temperature profiles  from bathythermographs and temperature
recorders show that Lake  Michigan  overturns  from top to bottom.  The
southern basin, whose  maximum  depth is 172 meters (5o5 ft.), overturns
                                   230

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FIGURE  7-34

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every year.  The northern basin, whose maximum depth is 281 meters (923
feet) probably overturns every year.  Overturning  occurs  only  during
early winter and early spring periods,  each about one month in length.
If no severe winds  occur in either period, the northern basin  may not
mix to the bottom.

       2.  A winter thermocline  at  a  depth of about 183 m (600 feet)
occurs in the northern basin.  Internal waves on the winter thermocline
suggest  that  amplitude  may  be  as great as 60 meters from trough to
crest.  Once the  winter thermocline has been  formed no  mixing occurs
below this depth.

       3.  Inshore vertical cooling and mixing  occur  rapidly  in mid-
winter with little or  no horizontal exchange with the main body of the
Lake.  This  barrier  is known  as the thermal bar and inhibits mixing.
Even though the temperature of both areas  (or zones) is  less than k®C
as shown in the 1961-62 winter data, a barrier still occurs.

       k.  The northern basin usually lags 30 days  or more  behind the
southern basin during the late spring and early summer warming period.

       5.  The  southern  basin  cools  at  a more  rapid rate than the
northern basin.

       6.  Typical temperatures for Lake Michigan for a season or month
of the year are  difficult to define.  The temperature range during one
month varies considerably between the two basins at any one  time.  The
temperature range for any given month may  be  expected  to vary widely
from year to year depending upon the severity of the weather.

       7.  Marked changes or configurations of the thermocline from one
end of the Lake to the other are characteristic of summer conditions in
the Lake.

       8.  Internal waves of a period near the inertial period, a little
less than 18  hours, occur constantly on the thermocline and are regen-
erated by every storm crossing the Lake.  The waves appear to be stand-
ing waves (see Chapter 10). In summer vertical velocities of 0.2 cm/sec
were found by calculating the change of the isotherms from one level to
another.  The formation of  internal  waves  expends  energy that would
normally produce mixing.

       9.  Alternating periods of warm  surface  water  and cold deeper
water at a water  intake may be due to internal waves or tilting of the
thermocline.

      10.  Under certain  conditions,  pollutants  discharged  into the
Lake could lie on the thermocline (because of similar densities) and be
                                  232

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brought to the surface during the summer period, by tilting or oscilla-
tions of the thermocline.

      11.  The existence of thermoclines  and  thermal  barriers during
extended periods of the year  greatly  reduces mixing of the  shallower
shore waters and the waters of the hypolimnion  with  the main  body of
the Lake.  Such  conditions  promote a buildup of persistent pollutants
discharged into the isolated waters.   Because of the prolonged periods
during which such conditions can continue, such buildups can impair the
uses of the waters adjacent to discharge points.
                                  233

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                              CHAPTER 8

                            BROGUE STUDIES

                                  *y

                   Akira Okubo and James L. Verber
Introduction

       Six drogue studies  were made in Lakes  Michigan and Erie and at
the mouth of the Detroit River.   These studies were intended to obtain
information on the scales and intensity of horizontal dispersion in the
Great Lakes.  The information, in turn, provides clues to the diffusion
of pollutants discharged  continuously  or  intermittently  from sewage
outfalls into the Lakes.

       The basic report was prepared for the Project by Dr. Akira Okubo,
Chesapeake Bay Institute, Johns Hopkins University.  Dr. Okubo assisted
staff members in outlining the  study  and  contributed touch toward the
technology used in the study.  Drogue Runs 01 and 02  were made in Lake
Michigan and 03 to 06 in Lake Erie.  Dr. Okubo submitted three reports,
one for each Run in Lake Michigan, and a final report including Runs in
Lake Erie.  Also included are the field techniques used (J.  S. Farlow,
31).

       The approach used was to photograph from an  airplane a group of
small floats attached  to submerged drogues (current-following devices)
as they moved past an array  of fixed  reference markers.    A series of
photographs  was made from a height of about 2kO meters above the water
surface once every 5 minutes for the first 2 hours  and then once every
10 minutes for at least another hour. At this height the 22.9-cm square
photographs depicted an area 360 meters square.   The photos were over-
lapped by 80 percent so that the small floats could be  located despite
the large areas of glare on individual photographs.  Sixteen fixed ref-
erence markers  were  anchored  about  180 m apart  in an approximately
rectangular grid. They were shape- and color-coded for positive identi-
fication.  The drogues were  launched  about 18 m apart, also in a rec-
tangular grid pattern and were also color- and shape-coded.  Between 50
and 90 drogues were used  each  day  at  each depth investigated, which
gave reasonable statistical stability.

                              Equipment

       The drogues  (Figure 8-l) were made from 1.2- x 2.4-m rectangles
of 198-gram (7-ounce) nylon cloth,  with  the  upper  and  lower  edges
folded over and sewn to form tubes.  Two such pieces were bent at right
angles at the middle and  joined together at the angles by two vertical
                                   234

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lines of stitching about 0.75 cm apart.   Two  2.4-m lengths of 0.75-cm
diameter, zinc-coated,  thin-walled electrical conduit were inserted in
the cloth tubes at the lower edge. Their ends were guyed by 0.19-cm di-
ameter nylon parachute cord so that the two pieces of  conduit bisected
each other at right angles. The upper edges of the drogue were supported
by 17 aluminum fish-net floats, each approximately 7.5 cm long and 4 cm
in diameter.  Slits in the upper edge of the cloth tubes containing the
fish-net  floats  allowed  air  to escape freely.  The assembled drogue
weighed about 4.3 kg in air when  dry and  measured 1.2 m high by 2.4 m
across overall.  When submerged in lake water, each drogue weighed less
than 0.22 kg (that is, one  more fish-net float would make it buoyant).
A length of nylon  parachute  cord  was  tied  around the two pieces of
electrical conduit and led up through the parallel  rows  of  stitching
holding the two panels  together to a  small float at the Lake surface.
The weight of the submerged drogue was sufficient to keep  this line as
nearly vertical as a diver can judge, and so its length  determined the
drogue's depth. The equipment is relatively indestructible and requires
no maintenance.

       The surface float (Figure 8-2) was a sandwich  consisting  of an
inch-thick  piece  of  styrofoam  held  in  place between tvo pieces of
quarter-inch plywood by an eyebolt, to which the  cord  supporting  the
drogue was attached.  The  surface  of the float had an area of 768 cm2
and its freeboard was about 0.63 cm.  Assuming a wind speed of 13 knots
and a  water  speed of 44.7 cm/sec, the drag of the supporting elements
is only about 1 percent of that of the drogue itself.  The  size of the
drogue is such that  it provides information on about 75 percent of the
horizontal turbulent energy that may be expected.

       Surface floats were made in triangular, rectangular, and circular
shapes, and their upper  surfaces  were painted  in one of five colors.
The red, green,  orange, and yellow were of reflecting paint; the white
was traffic paint.  As expected,  the  white floats were the hardest to
see, because they were easily confused  with  white  caps  and  glitter
spots.  Orange and red are the easiest colors to find from a boat or on
a  photograph.   Rectangles  are  the  easiest shape to pick out on the
photos.

       The floats were launched in  order  in  groups of 15, each group
member having the same number.   Each row contained only one shape, the
adjacent rows having  different shapes.  Each column contained only one
color, the adjacent ones having different colors.  This  ordered alter-
nation made it possible to keep track of the identities of 150 different
floats over the period of the study.  However, because the drogues tend
to sink to their designed  depth  at  different rates and because water
velocity  tends to change with depth, it is essential to photograph the
drogues during the period of  launching  as well as  after they are all
launched.
                                  236

-------
\\6  X9 XI
   rSTYROFOAM
  v x\ nN |/4" p|_YWoOD.
                                                       6"X9"Xl" STYROFOAM
                                                        ON 1/4" PLYWOOD.
                                    30
                            13/2 X4"Xl" STYROFOAM
                            ON 1/4" PLY WOOD.
                                    B
                                                             12.3
                                                               SCALE
                                                          0
                                                           _1

                                                          0
                                                                       I FT.
                                                                   I  I  f
                                                                      30 CM.
                                               BOLT (A,B,aO

                                               PLYWOOD TOP(A,B,aC)
                                                                    7
                                                             STYROFOAM
                                                             PLYWOOD
                                 LEFT END VIEW
                                       A
                                                                SCALE
                                                                         4IN.
                                                                         IOCM.
MATERIAL
AS SHOWN

FINISH
REFLECTING PAINT
                                                   GREAT  LAKES  -  ILLINOIS
                                                    RIVER  BASINS  PROJECT
                                                  DROGUE SURFACE  FLOATS
                                                          DROGUE STUDY
                                                  U S DEPARTMENT OF THE INTERIOR
                                              FEOtRAL WATER POLLUTION CONTROL AOMIN
                                                  LoMJ R»$ion           Chlcogo.lllifioit
                                237
                                                                       FIGURE 8-2

-------
       The reference markers (Figure 8-3) were each  made of two sheets
of plywood and styrofoam  which supported the ends of a 6.3-m length of
3.8-cm diameter, galvanized  steel  pipe.  One float was a square 1.2 m
on a side,  the other was a right  triangle made by  cutting one of the
squares in half along a diagonal. The floats, which were made of 1.9-cm
plywood with 25-Jj-cm styrofoam sheets nailed on the underside, were held
to the upper  side  of  the  pipe  by pairs of u-bolts.  The pipes were
capped to increase buoyancy.  Eighteen-inch  sections  of  old railroad
rails were used as anchors and  fastened to each end of the  marker  by
0.63-cin manila line.

       The photographer took  vertical  photos  with  a Zeiss RMK 15/23
camera with a 153 mm lens.  The camera was loaded with five 22 m  rolls
of  Kodak  aerial  Ektachrome  spliced  end  to end.  This magazine was
replaced by another similar one about the time the photographic interval
was changed from 5 to 10 minutes, making a total of about 255 a of film
used on each day of field work.  If camera tilt is less than 2 degrees,
the maximum distortion in the corner of the 22.9-cm square negative is,
at most, 10 microns.

                            Field Methods

       On an average field day, a larger vessel (ik m or more in length)
carrying the  assembled  drogues  and reference markers and two smaller
vessels (about 6.0 m long)  reached  the  study  area about 0830.  Test
drogues were set to the depths of interest, and  watched  for about 1/2
hour while  the  reference  markers were readied for launching.  When a
clear idea of the direction of drift was obtained, three parallel lines
of reference markers were  launched about  180 m apart  and parallel to
the direction of drift.  The  larger  vessel cruised slowly tossing off
markers with one anchor attached, while the small boats followed behind
attaching the second anchors in a taut  fashion  so  the  markers would
neither  translate  nor  rotate.  Three lines of four reference markers
each took about 20 minutes to set.  (There were four additional markers
remaining on board at the  end  of  this first operation.)  After these
first dozen markers had gone in, the test drogues were checked again to
see if any drastic changes in direction had occurred.  By that time the
photo plane was making a high level run (about 1,800 m above the water)
to be able to get at least one frame showing all the reference markers.
While it was making  this  run,  the  larger vessel started setting the
deep drogues about 18 m apart, working upwind, laying successive cross-
wind lines.  When  the  equipment  was  in good order, it took about 4 5
minutes to set some 75 drogues between two lines  of reference markers.
The pmtt-il boat followed the larger setting vessel, untangling any equip-
ment which became fouled during launching and righting capsized surface
floats.  After  the  deep  drogues  were  in,  the shallow drogues were
                                   238

-------
                               	21 0

                               	I2'0"
                             \]/2. GALVANIZED STEEL PIPE

                               8 1^2 X \7/8 O.D. END CAPS.
              3'6" —»-
                                                             SCALE
                                                         0            4FT.
                                                         I i i I i    I   I   I
                                                         ill   rTi T
                                                         0            I20CM.
      3^8 X 5/8 X 1^8 METAL STRAP
      WITH  U-BOLT
                                     —  PLYWOOD
                7    \
                                     END VIEW
                                                      STYROFOAM
MATERIAL
AS SHOWN
FINISH
REFLECTING PAINT
NOTE:
STYROFOAM NAILED
TO PLYWOOD
                                                                  SCALE
                                            0
                                            P
                                            0
                                                                          4IN


                                                                          IOCM.
                                   GREAT  LAKES  ~   ILLINOIS
                                    RIVER  BASINS  PROJECT
REFERENCE MARKER
     DROGUE  STUDY
                                                   U S DEPARTMENT OF THE INTERIOR
                                               FEDERAL WATER POL LUTtON CONTROL ADMIN
                                               Grtat LQK«« Rtgioi           Chicago, Illinois
                                  239
                                                             8-3

-------
launched in a parallel lane of reference markers.  Drogues at different
depths have been observed to move at right angles and also in directions
directly opposed to one another for some hours at a time.  This vas one
reason for putting out test drogues. The outer boundaries of the groups
of drogues should be checked at least once every 3/k hour, so that addi-
tional reference markers can be put in or  others shifted in such a way
as to keep the ground  surrounded.  General trends were noted and plans
were  laid  in  advance to maintain a usable grid  of markers among the
drifting drogues.  The photo  plane made  additional high level runs as
necessary. It began making low level runs (about 2kQ m above the water)
as the first drogues were set. These runs were made every 5 minutes for
approximately 3 hours, after which  the  interval  was  increased to 10
minutes for the remaining 2 to 3 hours.  At  the end  of about 6 hours,
the plane had used some 255 m of film and most of its fuel.

       After the plane departed  all  boats started collecting drogues,
and also reference markers, if this was the last day of the study.   At
least 3 hours were allowed, as finding the last half dozen usually took
considerable time.  About 95 percent of the drogues were recovered.

Analysis Methods

       The raw data from these  studies  were  reduced  to yield a time
series of the locations of a group of drogues at each depth.  The posi-
tions  of  the  drogues  were transformed by a computer program into an
absolute coordinate system fixed to the Lake.  New York University pro-
vided computer programs  for  the  studies.  The following calculations
were conducted by computer:  the means,  variances, and  covariances of
each group of drogues at appointed times, the distance-neighbor separa-
tions (the pair-program), and the dispersion of drogues with respect to
their initial positions.  A CalComp  plotter was used in the program so
that  graphs of a  group of drogues could be prepared for each depth at
selected times.  Lagrangian  correlations  of the drogue  displacements
were also  computed for two typical runs; however,  the results are not
included  in  this  report,  since  meaningful conclusions could not be
derived from them.

Description of Experimental Results

       On June 25 and 26, 196*4-, two studies (Run 1 and Run 2) were made
in Lake Michigan  about  2.k km  WWW of Indiana  Harbor,  Indiana, East
Breakwater Light, where the water depth is about 8.1 m (Figure 8-4). On
July 15 and 16, two  studies  (Run 3 and Run h)  were conducted in Lake
ti-ie about 8 km WSW of Colchester, Ontario, where the depth of water is
approximately  7-5 m (Figure 8-5).   Finally,  on August 15 and 16, two
more studies (Run 5 and Run 6) were made in Lake Erie about 5-6 km west
of Cleveland, Ohio,  West  Pierhead Light,  where the depth of water is
                                  240

-------
   87°40'
87°30'
4I°50'	
   67°40
                   LEGEND


                 A = Water Intake

                 7.3 = Meiers
                SCALE   IN  KILOMETERS
            GHTAT  LAKE'S  -   H_,MOC>
              RIvhR  BASINS   PRO,ECT


           MAP OF STUDIED AREA FOR
                   RUNS I 62
           U  . 'f t ..•' i Vt RJ !  ,  : '"f-  'NT1 •<  •>>

       FEDERAL WATER POLLUTION CONTROL AOMIN.
       Great Lakes Region           Chicago, Illinois
                                                                                :  t 8-4

-------
83°50'
83°00'
                                                                         	42° 20'
                                                                            - 42°00'
                    SCALE
                                          32

                                     Kilometers
                                                      GREAT  LAKES  -  luLiNOlS
                                                        RIVER  BASiNS  PROJECT
                                                            STU DIED  AREA
                                                             RUN 3 'RUN 4
                                                      US DEPARTMENT OF THE INTERIOR
                                                  FEDERAL WAT EL h POLLUTION CONTROL ADMIN
                                                  Great LaKes Region          Chicago,II,mois
                                                                           FIGURE  8-5

-------
about 12.6 m (Figure 8-6). AH of the aerial films have been developed,
but  computer  runs  have  not been processed for Run U, so this report
will exclude analysis of Run k.

       On  a  typical  experiment  or  run,  a total  of N-j_ drogues was
released at 6.1 m depth,  each being launched  about 18.0 m  apart in a
rectangular grid pattern.  In Runs 2, 3> and 6, after the 6.1-m drogues
were  released, a total of Ng  drogues was also released at 1.5-m depth
in a similar manner.

       A series of aerial  photographs  was  taken  from an altitude of
about 240 m once every 5 minutes or so for the first  3 hours  and then
approximately every 10 minutes for the rest of the experimental period.
The probable error in locating  drogues  is estimated at 1 to 2 meters,
the higher figure  to hold  for later parts of the experimental period.
The early photos for Runs 2, 3* a^d 6  were  not  used  in the computer
programs.  Thus,  for  these runs, the analysis of diffusion covers the
period  after both groups  of drogues  were set in  the water.  General
information on the runs is contained in Table 8-1.

       Drogue positions at some typical  times are shown in Figures 8-7
to 8-11, where the  coordinate  system is taken in such a  way that the
X-axis  points to the east  and the Y-axis  to the north.  Some drogues
could not be located,  chiefly because  they were outside  the field of
the aerial  photographs.  On a few occasions  some drogues failed to be
detected even though they supposedly  were in the field of  the photos.
The  approximate  positions  of  those  missing  drogues, however, were
obtained  by  interpolating  between the preceding and subsequent posi-
tions whenever possible.

       Group size did not always  tend to  increase with time.  Whereas
the 1.5-m drogues in Runs 2 and 6 and the 6.1-m drogues  in Runs 1,  2,
and 3 exhibited the tendency of growth of group size with time, charac-
teristic of turbulent diffusion, the anticipated increase in group size
was not immediately recognizable for the 1.5-m drogues in Run 3 and the
6.1-m drogues in Runs 5 and 6.

       Figures 8-12, 8-13, and 8-14 illustrate the time behavior of the
standard deviation for all the runs.   There  was, in fact, very little
dispersion of  the drogues for Runs 3> 5> and 6 as was mentioned previ-
ously; the drogues were  dispersed  over approximately the same area at
the end of a few  hours  as at the beginning  of the experiment, and at
times a certain number of drogues was noticeably reconcentrated  in one
location or another (see Figure 8-10). It is evident that those drogues
encountered  temporary convergences present at the depth of water where
the drogues were located.
                                 2^3

-------
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                                    RUN  I - 20 fttt  (6.1m)
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-------
     TIME   VARIATION  OF  STANDARD  DEVIATION  IN  THE  GROUPS  OF

                                DROGUES
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                                                     xxxx  x
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                                                   GREAT  LAKES  -  ILLINOIS
                                                    RIVER BASINS  PROJECT
                                                      TIME  VARIATION

                                                           RUN 3
                                                 U.S DEPARTMENT OF THE INTERIOR
                                              FEDERAL WATER POLLUTION CONTROL AOMIN
                                              Great Lukes Region          Chicago,Illinois
                                252
                                        FK3URE 8-13

-------
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253

-------
       The movement of the center of  mass of the  drogues and the wind
track on the day of  experiment are shown in Figures 8-15 to 8-19.  The
wind data are available from airports near the studied area, each loca-
tion "being indicated on the field maps (Figures 8A, 8-5, and 8-6) .  In
general, the  movement  of  the  1.5-m  drogues may be interpreted as a
result of the wind-driven current,  the direction of which was somewhat
to the right of the down-wind direction. On a change of wind the direc-
tion of the flow at 1.5 m changes within an hour  or  so.  On the other
hand, the movement of the 6.1-m drogues was generally against the local
winds. In other words, the drogues at 1.5 and 6.1 m moved in directions
opposed to one another.  This implies that vertical shear in horizontal
velocity did exist in the experimental area.  Typical velocities at 1.5
and 6.1 m are estimated to be k and 2 cm/sec, respectively.

       During the summer, a sharp  thermocline develops at $.k to 6.1 m
in the western part of Lake Erie.  Thus the 6.1-m drogues were situated
in or a little below the thermocline. The summer thermocline is usually
not so conspicuous in southern Lake Michigan as in Lake Erie. The 6.1-m
drogues in  Lake  Michigan  were located below mid-depth, where a rela-
tively weak  stratification  is  present.   The  movement  of the 1.5-m
drogues  should represent  the  flow in the surface layer, above 3.0 to
       The wind factor,  the  ratio  between  the current speed and the
wind speed, is 0.008 at 1.5 m in Lake Michigan  and in Lake Erie south-
east of the Detroit River, but the factor in Lake Erie off Cleveland is
about two times higher, i.e., 0.017. On the other hand, the wind factor
at 6.1 m ranges between  0.005  and 0.008,  the only exception to these
values occurring in Lake Erie southeast of the Detroit River, where the
drogues were set close to  the bottom.  On days with moderately strong,
steady winds there should be a corresponding steady and uniform current
in the surface layer, the direction of  which is nearly parallel to the
wind.  The presence of boundaries should  modify  the  current pattern;
thus, close to  the shoreline the mean current is nearly parallel to the
shoreline even if the wind is offshore or onshore.

Characteristics of Diffusion

       As previously mentioned, the standard deviations of the group of
drogues do not necessarily  reveal a regular  pattern of turbulent dis-
persion.   In  the  case  where  suppression  or  reversal of diffusion
(apparently by convergence) is observed,  no diffusion constants can be
derived from the  variation of standard deviations with time.  Instead,
the dispersion of drogues with  respect  to their  initial position was
computed  for each of the eight groups of drogues.  By doing so, we can
regard the dispersion of drogues as if they were released consecutively
from the same point,  provided  that the turbulent field is homogeneous

-------
  400


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25 JUNE 1964
          Ohr
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                                    DROGUES IN
                                      10 hr
                                                  WIND
                                                                 > END OF STUDY
                                                          I5hr
      -25      0
                               50
                                      100
                                                                             20hr
                                                                            -0
 150
200
                                      Km
                                                    GREAT  LAKEb  -   ILi-iNO'S
                                                      RIVER  BASINS  PROJECT
                                                      MOVEMENT OF DROGUES
                                                          8 WIND TRACK
                                                             RUM  I
                                                   US DEPARTWFNT ";F THE INTFRlOP
                                               FEDERAL WATER POLLUTION CONTROL ADMIN.
                                               GreolLcNesR*gicn           ("^it^j^'nr
                                  255

-------
                               DROGUES
   200
   Y
  (m)

- 200
2.5 hr
-400
       I.Ohr
           00.5hr
                         6.1 m
                                                             2 5
                                        Ohr
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                                    WIND
400
600
    100
     Km
                                     100
                                              200
                          Km
                                                 GREAT  LAKES  -  ILLINOIS
                                                   RIVER  BASINS  PROJECT
                                                   MOVEMENT OF  DROGUES
                                                       8 WIND  TRACK
                                                          RUN  2
                                                US DEPARTMENT OF THE INTERIOR
                                            FEDERAL ViATFP  POLLUTION CONTROL ADMIN
                                            Great  Lakes Region          Chicago,Illinois
                              256
                                                      FK,URE 8-16

-------
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15 JULY 1964

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GREAT LAKES - ILLINOIS
RIVER BASINS PROJECT
MOVEMENT OF DROGUES a
WIND TRACK - RUN 3
U S DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL AOMIN
Great Lakes Region
Chiccqo.lilino.s
257
                                       FIGURE 8-17

-------
 200
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                                DROGUES
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STUDY

                         Km
                                                 GREAT  LAKES -  ILLINOIS
                                                   RIVER  BASINS  PROJECT
                                                  MOVEMENT OF DROGUES
                                                   a WIND  TRACK -  RUN 5
                                                U S DEPARTMENT OF THE INTERIOR
                                            FEDERAL WATER POLLUTION CONTROL ADVIN
                                            Great LaKes Region           Chicago I.lino.s
                               258
                                                       8-18

-------
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100
GREAT LAKES - ILL
                                         50
                            Km
                                259
                                                     MOVEMENT OF DROGUES
                                                      a WIND TRACK-RUN 6
              U S DEPARTMENT '> '--f  IN rfw,.-,R
          FEDERAL WATER POLLUTION CONTDOL A(;MiN
          Great Lakes Region             'r  ,   nc s

                                      C-ijRE 3-19

-------
(Hinze, 38).  The adverse influence of  convergences  on the dispersion
of the drogues may be partially eliminated in this manner. Figures 8-20
to 8-22 show the results.

       When the scale of dispersion  becomes  large  compared  with the
largest turbulent eddies present, its growth comes to resemble molecular
diffusion, i.e., the standard  deviation increases with the square root
of time and a constant  diffusivlty  can be defined.  It is, of course,
much larger than the molecular diffusivlty.   Thus, an effective diffu-
sivlty, Ke, may be computed from the formula
where D^ denotes the variance of drogues  at  a  time t with respect to
their initial positions.

       For the,1.5-m drogues in Run 6 and  the  6.1-m drogues in Run 3,
however, the t*  relationship  was  not  observed  during the period of
experiment  (see Figures 8-21  and 8-22).  Instead, a t3/2 relationship
characteristic  of  relative  diffusion  in homogeneous  turbulence was
present in the D^-t diagrams.  This behavior may suggest that the scale
of the large eddies  responsible  for  the horizontal dispersion of the
drogues was not  small in comparison with the  group-size of drogues at
the end of the experiment.

       The values of Ke computed from  (l) are shown in Table 8-2.  All
the values of the effective diffusivlty lie in a relatively narrow range
from 2.9 X 10* to 5.5 X 101* ca^/sec, though slightly  higher values are
seen at 1.5 m.

       The effective diffusivlty may also  be  expressed as the product
of v1, the intensity of  turbulence and L, the integral scale of turbu-
lence (Hlnze, 3&):

          Ke = v'L  .                                           (2)
The scale L is a measure of the large-scale eddies and could be computed
from knowledge  of  the  Lagrangian  velocity  correlation.  Since  the
Lagrangian  correlations  were  unobtainable  from  the  data,  we must
                                  260

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                                  RUN  3
                          x - 1.5 m      o = 6.1m
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               STANDARD DEVIATION OF DROGUES WITH RESPECT
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                                    262
                                                   GREAT  LAKES -   ILLINOIS
                                                    RIVER  BASINS  PROJECT
                                                STANDARD   DEVIATION
                               U S DEPARTMENT OF THE INTERIOR
                           FEDERAL WATER POLLUTION CONTROL AUMIN
                           Great LaNes Region           Chicago I iincxs

                                                     ~ GL/RE 3-21

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estimate L by another  method.  As  previously  pointed out, D versus t
exhibits  an asymptotic  behavior  vhen  the scale of diffusion becomes
larger than L.  Accordingly, the length-scale L may be obtained approx-
imately from the D-t diagram as follows.  Do, which is the lowest value
of D for which D is proportional to t?, is determined from the D versus
t figures.  Provided the distribution of drogues is gaussian, a charac-
teristic length-scale  of  distribution  may be given by k Do; that is,
approximately 95 percent of the drogues will  be found within  the dis-
tance i2 Do from the mean of the distribution. Hence, we take L = k DO-

       Having obtained the values of Kg and L,  we are now able to com-
pute v' by (2).  The results are summarized in Table 8-2. The intensity
of turbulence differs  very little between Lake Michigan and Lake  Erie
and also between the depths of 1.5 and 6.1 m.  This is primarily due to
the fact that the mean velocity was nearly identical except at 1.5 m in
Run 6, for  which  no  estimate  of  intensity  of turbulence was given
because of the lack of an asymptotic relationship between D2 and t. The
relative  intensity of turbulence, the ratio  between the  intensity of
turbulence and the mean velocity, is also computed (see Table 8-2). The
values range from 10 to 20 percent.

       One way of treating relative diffusion is to observe the rate of
increase of mean separation of a pair of  drogues with the same initial
separation, X^Q.  Figures 8-23 to 8-26 show the root-mean-square separa-
tions versus time for various initial  separations.   For small initial
separations, the root-mean-square separations  increase  regularly with
time  even in the case where the group of drogues encountered converges
so that suppression or  reversal  of dispersion  occurred.  Small-scale
turbulent  motions  allow  a  pair of drogues with small separations to
diffuse regularly, provided that the  characteristic  scale  associated
with the convergences or divergences is large compared with the separa-
tion of the drogues.  On the other hand, the effect of the convergences
on dispersion is marked for a pair of drogues having large initial sep-
arations .  Apparently the large-scale convergences prohibit the drogues
from diffusing regularly.  The results of the pair-program suggest that
the scale of the convergences was on the order of 100 meters.

       A theoretical treatment  of  this relative diffusion, presumably
valid for the ideal  case of homogeneous  turbulence  and uniform  mean
flow has been developed by Batchelor (k).  Dimensional arguments on the
basis of  similarity theory  of turbulence are applied to three regimes
of relative dispersion.  These regimes are characterized by the follow-
ing behaviors with time of  the mean square  separations  of a  pair of
drogues which start with a same initial separation,
                                  265

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                                        « ta  ~ ^0     E'1/3 (initial)

                                                                (3)


         crr  =  c2 E t                ,  t » t             (intermediate)
         crr  c~= t                     ,  t -* oo               (asymptotic)

                                                                (5)  .
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-------
271
                                   FIGURE  8-2?

-------
272
FIGURE e-28

-------
FIGURE  8-29

-------
                              
-------
by Okubo (5) and Bowden (12).   Horizontal  dispersion  of drogues in a
lake should also be described by those  theories with  minor  modifica-
tions, among which either Joseph and Sendner's theory (U6) or Okubo and
Pritchard's theory (58) is a satisfactory model for our purposes.

       Both theories predict the  temporal  behavior  of  the  standard
deviation of the distribution from a point-source as
                                                              (T)
Ft
                                                              (8)
where wand  P represent a diffusion velocity in Joseph-Sendner's theory
and Okubo-Pritchard's theory, respectively.   For dispersion of drogues
with a finite initial separation, however, equations (?) and (8) should
be modified as
     crr = u (t + to)                                        (9)
              P (t + t0)  ,                                (10)


where to is defined to be a fictitious time at which we regard the group
of drogues as concentrated at a point.

       Figures 8-31 to 8-35 show the standard  deviations  versus  time
for a pair of drogues starting with the same separations.  In each Fig-
ure we also draw a theoretical line to fit the data points, so that the
values of w and P may be obtained.  The results are shown in Table 8-2.

       According to theory,  the  diffusion  velocity  is  a measure of
intensity of turbulent diffusion.   Thus the turbulent diffusion in the
surface layer, say at 1.5 m, seems to be more intense in Lake Erie than
in Lake Michigan;  but in the deeper layer,  say at 6.1 m, the diffusion
velocity in  Lake Michigan was  higher  than that of Lake Erie.  In the
sea, for comparison,  the  diffusion velocity w ranges from 0.7  to 2.5
cm/sec (58) while Pritchard and Carpenter (60) found  w = 0.2 cm/sec in
Conowingo Reservoir.
                                  275

-------
FIGURE  8-31

-------


inn ,.J

( m)









J .X"^



Q*^^,
0
STANDARD DEVIATION OF A
DROGUES VERSUS TIME
RUN 2 - 1.5m
Jk = 20m

X^

RUN 2- 6.1m
0 - 40m
^^, o'
^^^
)


o
X^




o

2
t (hr)
PAIR OF




^
o



^

-

S
s^






4



200
100
(m)
0
GREAT LAKES - ILLINOIS
RIVER BASINS PROJECT
STANDARD DEVIATION
PAIR VERSUS TIME
U S DEPARTMENT OF THE INI ERlOR
FEDERAL WATER POLLUTION CONTROL ADMIN
Great Lakes Region ^hictQOh.'nc.s
277
- GORE 8-32

-------
        200
       100
  0V
  (m)
STANDARD  DEVIATION  OF   A  PAIR   OF

DROGUES   VERSUS   TIME
                                                    GREAT  LAKES —  ILLINOIS
                                                     RIVER  BASINS  PROJECT
STANDARD   DEVIATION
  PAIR  VERSUS TIME
                                                  U.S DEPARTMENT OF THE INTERIOR
                                              FEDERAL WATER POLLUTION CONTROL ADMIN
                                              Great Lakes Region            Chicago.liiino.s
                                278
                    FIGURE 8-33

-------
                                  RUN  5 -  6.1m
 200
(m)
100
    STANDARD  DEVIATION   OF  A  PAIR  OF


    DROGUES   VERSUS   TIME
                                                     GREAT  LAKES  -  ILLINOIS
                                                      RIVER  BASINS  PROJECT
                                                     STANDARD  DEVIATION

                                                       PAIR VERSUS TIME
                                                    U S DEPARTMENT OF THE INTERIOR
                                                FEDERAL WATER POLLUTION CONTROL AOMIN
                                                Great Lodes Region            Chicugo lilino.s
                                   279
                                                                         FIGURE  8-34

-------
200
(m)




»













RUN 6- 1.5m
JU * 20m
0

O
X
*/
/
o o
/{*
/O °
0 / o
°0
o





3
0


RUN 6 - 6 Im
J) - 40m






/
/




0
2
t (hr)
STANDARD DEVIATION OF A PAIR OF
DROGUES VERSUS TIME












O
00^

3 4






200
CrV
(m)
100

0
GREAT LAKES - ILLINOIS
RIVER BASINS PROJECT
STANDARD DEVIATION
PAIR VERSUS TIME
U S DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL ADMIN
Great Lakes Region Chicugo.lllino s
280
8-35

-------
       Noble (56) measured the  rate of  dilution of a dye patch in the
surface water of Little Traverse Bay of Lake Michigan. A Joseph-Sendner
diffusion velocity of  0.3 cm/sec was selected  to obtain a good fit to
the experimental data.  The  value  is in good agreement with the value
at 1.5 B obtained in the drogue study in Lake Michigan.

       Csanady  (22) studied the dispersion  of  small  floating objects
and of fluorescent dye in Lake  Huron at  Douglas Point.  The  scale of
energy-containing  eddies was consistently  on the order of  10 meters,
ranging from k to 20 meters, which is slightly larger than that obtained
in the drogue  studies, while  an order  of magnitude  estimate for the
intensity  of turbulence  was 0.5 to 0.7 cm/sec  in the surface  layer,
which should be  compared with the values 0.4 to 0.5 cm/sec obtained at
1.5 m in the drogue studies.  By using  Csanady's data, we  can compute
the rate of energy-dissipation from equation (6). The result shows that,
in spite of a wide scatter  of individual  values ranging from 1 X 10~5
to 6 X 10-* erne/sec^, the average value of E takes 3.5 X KT* cm2/sec3,
which is quite consistent with  the value of E at 1.5-a  depth obtained
in the drogue studies.

       Csanady  (23) also  studied  diffusion  of fluorescent dye from a
continuous source in the western basin of Lake Erie.  Two measured dif-
fusivities were 2.6 X 10^ and k,k X 10^ cm?/sec in August. These values
are very small compared with  those obtained in the drogue studies.  If
we accept a well-known law that the apparent diffusivity is proportional
to the k/3 power of the scale  (Richardson, 63) Csanady's values  would
be close to the  values of  the drogue studies;  thus  Csanady's values
would correspond to 1.7 X 10^  and 2.8 X 10^ cn^/sec for a scale of 2^0
meters (Do estimated to be 60 meters),  while the effective diffusivity
in  Run 1 is 2.9 X 10^ cm^/sec for the same scale, and the agreement is
good.

       It may, therefore,  be  concluded  that  the values of diffusion
characteristics  estimated  in  the present study are  consistent  with
those obtained in other diffusion studies of the Great Lakes.

Theoretical Models of Pollutant Diffusion from Continuous Sources

       The distribution of a pollutant  from a continuous source may be
considered  as  the  sum  of the distribution of an infinite  number of
infinitesimal instantaneous sources  discharged  in a rapid sequence of
time. Under this assumption, it is possible to superpose a solution for
an instantaneous source with respect to time to obtain the distribution
of concentration for  the case  of continuous  discharge.  Thus, in the
case where  there is a variable  flow, U(t), and  where a pollutant  is
discharged at a  variable rate, Q(t),  from a point source at (xo, yo),
                                  281

-------
the concentration,  Sc(x,y,t),  at (x,y) at t after  initiation of dis-
charge is given by
  Sc(x,y,t)=J  S&lls^-x,-  J   U(t")dt",y-y0,t')dt'  ,  (ll)
   c

              n                t-t
where 8j represents  a concentration  for instantaneous  release from a
point  source  of  unit intensity; D is the depth of water within which
the pollutant is assumed to be mixed uniformly.  The depth,  D, may  be
taken as  the mean depth in nonstratified water and as the depth of the
thermocline in stratified water.

       Concentration  from  a  finite-sized  source can  be obtained by
integrating (ll) with respect to xo and yo over the domain of source, A:
               t                           t'

  Sc(x,y,t) =  Jdt'  JJ^0dy0§Sl(x-x0-  J   Udt",y-y0,t')  ,(12)
   c

               o     A                   t-t1
where q.(xo»yco*1) ^B *^e ra^-e  °f discharge  of pollutant per unit area
of the source.

       The concentration  distribution  from a  finite  source  becomes
identical with  the  concentration from a point at sufficient  distance
from the source. If the distance is more than several times the size of
the source, the finite source can be regarded, to a good approximation,
as a point source with the same total rate of discharge.

       We shall take Okubo and Pritchard's  solution  for Sj, since the
solution has a mathematical  form which  can easily  be integrated with
respect to time;  Joseph and  Sendner's  solution  cannot be integrated
over time  to  yield an analytical  expression.   Okubo and Pritchard's
theory gives



 Sj(x,y,t) = -\-2 exp{- ^~f}   .                         (13)
             itu t         w t
                                  282

-------
Substitution of  (13) into  (ll) provides the concentration  distribution
from a continuous point-source with a  given release  rate Q and  field
velocity U.  Consider  the  special  case  of uniform flow and constant
rate of discharge at xo = yo = 0.  Equation  (ll)  can  then  be easily
integrated to give

                - __    ~   da
where        ^J -  Z   e          : is equivalent to the error function.
       The concentration  along the central  axis  of a pollutant plume
(y = 0) takes the following simple form:

Thus the concentration down the central line of plume  varies inversely
with x for x ^ x^  (l - 2.326 $) , where x^ -  Ut and decreases  rapidly
at  large  distances (x >  x^  ).  At the point x^  (the location of the
center of mass of the first patch released) the concentration is exactly
one-half  of what it would be if it decreased everywhere inversely with
x.  As time  goes on, the inversely linear  regime extends  farther and
farther from the  source.  The  upstream  concentration  reduces  quite
rapidly with the distance from the source.

       The situation where U is not constant, but a function of time, is
identical with the foregoing except that the releases are not uniformly
distributed  along  the  center  line  of the plume, being more closely
spaced when released near slack water  than  when  released under swift
current conditions.  However,  this more general case cannot be handled
except by  computer.   Carter (l?) used the Okubo and Pritchard solution
to compute an exclusion area around a sewage outfall in a tidal estuary.
He considered the constant current model to be adequate under conditions
of variable Q   and U, if some care or adjustment was made for the ratio
 GJ/U.
       Equation (l4) may  also  be  applied to a nonsteady case after a
change of current takes place in a completely opposite direction. There
we consider only a newly started plume.  In fact,  the  old plume makes
                                  283

-------
some contribution of  contamination  to the  area  of concern,  but the
amount should be negligible compared with that due to the new plume.

       Close to the shore area the effect of boundary must be taken into
consideration.  Fortunately,  the currents are  predominantly longshore
in the regime, so  that the method  of images may be applied  to handle
the proper boundary conditions  (Carslaw and Jaeger, 16).   Thus, where
there is a constant current parallel to a straight shoreline and a point
source is located  at  shore,  the  concentration  distribution will be
simply twice that derived from equation (l4) .

Prediction of Pollution Distribution

       The foregoing solutions for a  continuous  release  with a given
rate of discharge contain only the physical parameters w, the diffusion
velocity, and U, the mean velocity.   Since the drogue studies provided
information on probable values of these parameters,  we may now predict
the  concentration  distribution of pollutant on the basis of the solu-
tions.
       First of «.!!. we must clarify our pollution problem.  In southern
Lake Michigan east of Chicago,  the main  sources  of pollution are the
Calumet River system discharging into Calumet Harbor and Indiana Harbor.
The area  of  the  drogue  studies  lay between these two sources.  The
closest water intake is located  k.O km SE of Calumet  Harbor and about
6.U km NW of Indiana Harbor.  Other  water  intakes  are situated about
6A, 9.6, 20.8, and 2?. 2 km north of Calumet Harbor.  The  shoreline of
the area can be  approximated by a straight boundary.  The two  sources
of pollution may be regarded  as point sources placed at the boundaries
so far as the  concentration  distributions at  these water intakes are
concerned.  Distances of these water  intakes from the shore are 1 to k
miles.  A depth  of 8 m is considered to be the  mean depth of the area
studied.

       In western Lake Erie north  of  Cleveland,  the main  sources of
pollution are  the  Rocky River  and the Cuyahoga River. In addition, a
300-m diffuser of sewage  effluent  is proposed for  the eastern end of
Breakwater.  Water intakes are located at about k miles NW of the mouth
of Cuyahoga River.   Approximate distances from these intakes either to
the Rocky  River or to the diffuser  are 9.6 km.  The shoreline of this
area can also be assumed  to  be a straight  boundary.  The size of the
pollutant sources, e.g., the width of the mouth of the Rocky River, may
also  be assumed to be small with respect to the distances to the water
intakes.  A depth of 12 meters is taken as the mean depth of the area.

       In western Lake Erie south of the Detroit River, the main source
of pollution  is  the  Detroit  River,  which  discharges  5,150 m3/sec
                                   281*

-------
 (l75>000 cfs) of water tinder  average  conditions   (Hunt,  ^2).   We  will
 consider the distribution of pollutant in the shore regime of the State
 of Michigan,  extending from  Pointe Mouillee to La Plaisance Bay;  this
 region may be assumed  to be semi-bounded  by a straight   shoreline.  A
 depth of 5 meters is taken as the mean depth of the area.   The width  of
 the lower Detroit River, being about 6.^ km, cannot be regarded  as  small
 as far as the studied area is concerned.

 I) Predictions for Lake Michigan (east of Chicago)  and Lake Erie (north
 of Cleveland).
       We  shall  choose  the  solution   l^) , multiplying by 2 for the
reflective boundary condition at y = 0,  for  our  predictions.  Let us
transform the solution into a nondimensional  form by taking b as a rep-
resentative length-scale and the mean velocity, U,  as a representative
velocity.  Designating u>^ = »»/U, K^ = x/b, y-^ = y/b, and t± = t/(b/U),
we express the solution as
      C =
                                                                   (16)
                 A/JfDbUS    S
      where  C - - - - c-^
      with   S  =— -  .                                        (10)

       The reference concentration,  So,  is  what we would obtain if a
pollutant released during  a  time  interval  T were mixed    uniformly
throughout a volume of water,  ,/jtbDU/T.     Thus, if a river discharges
a pollutant, Sj. being  its concentration, at a speed of Ur at the mouth
of width br and depth Dp, the reference concentration is given by
                                   b  D U
                                  285

-------
        A convenient unit   of b   is  a mile  for  the  two areas.  Thus,
 appropriate ranges  of x^ and y± for prediction of  concentration of  con-
 taminant vill be     -5  g x   s 20 and 0  S y   ^  IO.TWO values of WT  are
 selected  from  Table 8-2:1 u-^ - 0.2 and 0.4.   These represent the  two
 extreme situations.  Figures 8-36 and  8-37  show   the steady-state
 distributions  of   pollutant for   the  cases   where  w^  = o.2 and  0.4,
 respectively. Concentrations along the  shore (yi - 0)  and at  yt - 2 and
 y!  « 4 are shown  in Figures 8-38  to 8-1*0 for   the given   values of ^3..
 It  may be noticed that, for  the larger ^^_,  more  contamination spreads
 laterally, especially   in   the region of small  values  of xx,   and  some
 contaminant is found in the upstream region.

        For the nonsteady case we shall  restrict the computation to the
 central line, yi «  0.  Figures 8-4l and 8-42 show  the  distributions for
 various times with u^ - 0.2 and 0.4,  respectively,  where the unit of
 time t* corresponds to the  time it takes a pollutant particle  to travel
 a distance xx - 20  with the  speed  Uj  thus,  at the end of t* » 1, the
 center of mass of the first  patch  released has  just arrived at x-, « 20,
 i.e.,  20 miles from the source.

 II) Predictions for Lake Erie (south of the  Detroit River).

        A steady-state case  for a finite source in semifinlte  space has
 to be  treated by numerical  computation.  The following result  is due to
 H. H.  Carter (unpublished notes).

        Take  a plane  source of length b  and  depth  D  extending from the
 shoreline perpendicularly into the Lake.   A nondimensional form of the
 solution is written as
p I    j   p    -     i - / - GXTh ~   - /•  -        - i  P  X
                                              .              .
                          22vU/2  *H    2?   2~   i   FT /
                           -
             1 + « { M (x 2+(y\y 2))l/2 }]  dyo  '              (^


The right-hand side of (19) is handled by machine computation. Thus the
relative concentration at a specific position depends only on the value
of the parameter u)^.

       Figure 8-43 shows the result of computation of the relative con-
centration for  the  case  Wi » 0.2.   In  the region where X]_ * 5, the
                                  286

-------
LL)
O
or
O
Q.
O
cr
o
h-
<
CE
(-
Z
ui
o
z
o
o
UJ
>
UJ
cr
             o
             o
             o
o
o
                 \
                                                 o     o
                                                                                      O
                                                                                      tvj
                                      If)
                                                                                      tn
                                                                                           — cc
                                                                                              a.
                                                                                            I
                                                                                              in
                                                                                           co?
                                                                                           UJ 
-------
w
o
CE
3
O
OT
O
Q.
O

UJ
tr
o

§
                      \
                                                        I
                                                                       O
                                                                       CM
                                                                                     UJ
                                                                                     -a
                                                                                 Z
                                                                                 o
                                                                                 op
                                                                                 (t
                                                                                     V)
                                                                                  UJ
                                                                            <
                                                                            m
                                                                                           r^  — .
                                                                                           <  3
                                                                       in
                                                                                 V)

                                                                                 >
                                                                                 o
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                                                                                 UJ
                                                                                 I-
                                                                                 (f)
                                                                         
-------
            CONCENTRATION  ALONG   THE  SHORELINE
100
50
20
10
0.5
0.2
O.I
     O.I
                  \
                       \
                                  L
UJ,= 0.2
                                   U), = 0.4
               S
                                                     \
              (0
50    100
                                    X,
                                                GREAT LAKES  -  ILLINOIS
                                                 RIVER  BASINS  PROJECT
                                             RELATIVE CONCENTRATION
                                               US DEPARTMENT OF THE INTERIOR

                                            FEDERAL WATER POLLUTION CONTROL ADMIN
                                            Greot Lakes Region           Chicago,lllinois
                              289
                                      8-38

-------
 0.5
 0.2
 O.I
0.01
 0.001
 0.0001
                                                 90    100
                            X|
                                            GREAT LAKES  -  ILLINOIS
                                             RIVER BASINS PROJECT
                                           RELATIVE  CONCENTRATION
                                                   AT y,  =  2
                                           U S DEPARTMENT OF THE INTERIOR
                                       rEQERAL WATER POLLUTION CONTROL AOMIN
                                       Great Lake* Region           Chicugo,Illinois
                         290
FIGURE  8-39

-------
o.a
0.2
01
0.01
 0.001
 0.0001
                                               50      100
                                              GREAT  LAKES  -  ILLINOIS
                                               RIVER  BASINS  PROJECT
                                            RELATIVE  CONCENTRATION

                                                   AT  y,  =  4
                                             U S DEPARTMENT OF THE INTERIOR
                                         FEDERAL WATER POLLUTION CONTROL ADMIN
                                         Grtot Lodes Region           Chicago Illinois
                            291
                                                                  FIGURE  8-40

-------
 10
 O.I
0.01
0.001
                                                              UJ,  = 0.2
                                                     100
                                                  GREAT  LAKES  -  ILLINOIS
                                                   RIVER  BASINS  PROJECT
NON-STEADY
           AT
                                                               DISTRIBUTION
                                                                 =  0(0.2)
                                                 U.S DEPARTMENT OF THE INTERIOR
                                            FEDERAL WATER POLLUTION CONTROL ADMIN
                                            Great Loktt Region            Chicago,Illinois
                                292
                                                                      FIGURE  8-41

-------
                                                          LU = 0.4
0 01
0 001
                                                 GREAT  LAKES  -  ILLINOIS
                                                  RIVER  BASINS  PROJECT
                                              NON-STEADY  DISTRIBUTION
                                                        AT y,= 0 ( 04)
                                               'U S DEPARTMENT OF THE INTERIOR
                                            FEDERAL WATER POLLUTION CONTROL AUMIN
                                            Great LaKes Region           C
                                293
FIGURE  8-42

-------
— UJ
_J ->
.J O
- cr
   a


«!>8
ui <7J
* <
< 00

   cr
         Z
         O
         UJ
         o
         Z
         o
         o
         UJ
         UJ
         o:
z
{£

2
UJ
CJ
z
o
o
UJ
or
u.
O
^   "
m   *
?   o
UJ
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<
 I    •*•


I   5
S   O
(-   o:
                       z
                       S
                       Q
                   t--   3
         FiGuRF   8-43

-------
relative concentration  differs appreciably from that of a point-source
solution, as may be expected.

Discussion

       The main purpose of the drogue studies in Lake Michigan and Lake
Erie was to provide  basic  information  on  the scale and intensity of
horizontal diffusion.  The use of marked drogues for studying turbulent
diffusion, however, has limitations.  One limitation is that the drogue
has a  finite size so that small-scale turbulence will not be sensed by
the drogue.  The drogue study will, however,  obtain information on the
medium-scale and larger turbulence.

       Another limitation is that the drogue provides no information on
the vertical component of turbulence. The effect of vertical diffusion,
in particular  when  combined  with vertical shear in the mean flow, on
the mixing of a solute has recently  received much attention by various
investigators (Bowden, 13, etc.).

       Csanady (22) reported that  longitudinal (i.e.,  along mean cur-
rent) diffusion of a dye patch  in Lake  Huron  was considerably faster
than lateral diffusion and the difference was attributed  to  the shear
effect.  In other words, horizontal  diffusion is  greatly accelerated,
compared with  diffusion  in  uniform flow,  in complex currents.  Thus
effective longitudinal-diffusivities  due  to  the  shear effect may be
comparable  with apparent diffusivities found by purely two-dimensional
experiments, e.g., drogue studies.   This may suggest that our estimate
of the horizontal diffusion obtained from our  drogue studies should be
regarded as a lower limit for mixing in a  lake.   In  other words, the
drogue study  provides  upper  limits  of  steady-state  concentrations
resulting from the distribution of a pollutant.

Summary

       The results of the drogue studies in Lake Michigan and Lake Erie
are summarized as follows:

       1.  More than half of the groups  of  drogues  showed  a regular
pattern of turbulent  dispersion, whereas a few groups exhibited a sup-
pression or reversal of diffusion caused primarily by convergences.

       2.  The movement of the 1.5-m drogues was generally in the direc-
tion of local winds. On the other hand, the 6.1-m drogues moved against
the winds.   The  existence  of  vertical  shear  is  obvious.  Typical
velocities are k and 2 cm/sec at 1.5 and 6.1 m, respectively.
                                  295

-------
                                                         U            k
       3.  An effective diffusivity  ranges from 2.9 X 10  to 5-5 X 10
cn^/sec.

       k.  The intensity of  turbulence differs  little between the two
Lakes.  A typical value for the intensity of turbulence  is 0.3 to  0.4
cm/sec.

       5.  In Lake Erie the rate of energy dissipation at 6.1 m is less
by an order of magnitude than that at 1.5 m.  A similar order of magni-
tude exists between the two Lakes at 1.5-m' depth, a typical value being
2 X 10-^ cm2/seC3.

       6.  The length-scale of the energy-containing eddies is estimated
to be several meters.

       7.  Diffusion velocities  according  to  the theories of Joseph-
Sendner and  Okubo-Pritchard  are also computed.  The result shows that
the turbulent diffusion in the surface  layer seems to be more  intense
in Lake Erie than in Lake Michigan.

       8.  Generally speaking,  the values of diffusion characteristics
obtained in the drogue studies are consistent  with  those  obtained by
other methods, e.g., dye studies.

       9.  Some predictions of concentration  of  a  pollutant which is
discharged  continuously  are  given on the basis of superposition of a
solution for an instantaneous point-source.
                                  296

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                              CHAPTER 9

                       METEOROLOGICAL STUDIES
Introduction

       Meteorological studies were  conducted  on Lake Michigan in con-
junction with the work described in other parts of this report, for the
purpose  of gaining knowledge  about  the relationship of lake currents
to weather. The conception, planning, and conduct of these studies were
achieved through a cooperative  arrangement  between  GLIRB Project and
the U.S. Weather Bureau — now a part of Environmental Science Services
Administration (ESSA).

       ESSA provided a resident  meteorologist  on full-time staff duty
with the Project.  From  the  inception of  the study through November,
1964, this  position was filled  by Mr. George Williams (now deceased);
his place was taken by Mr. J. B. Holleyman.   Technical guidance on the
part of ESSA came from Dr. D. L. Harris.

       The original intent  of  meteorological  studies  was  to  learn
enough about  the  relationship  between  winds over the Lake and winds
over adjacent land to be able to forecast lake winds from land observa-
tions, perhaps  supplemented  by  data from ships.  In addition, it was
hoped that sufficient knowledge about the  response of lake currents to
wind regimes  would  be  gained to permit translation of wind forecasts
into current forecasts.  As  will  be seen, this far-reaching objective
has been only partially achieved to date.

       The network installed in Lake Michigan late in 1962 consisted of
33 current meter stations with subsurface temperature recorders attach-
ed.  Twenty-two of the stations also had instruments for recording wind
velocity.  The network was in operation during 1963 and 196^.

       During this  time  some  of  the  instruments  were  damaged  or
destroyed,  thus reducing the size of the network. Figure 9-1 gives the
location of each of the  network  stations and the type of instrumenta-
tion  in operation as well as the period of operation  of each station.
Table 9-1  shows  the wind  data available from the network stations on
Lake Michigan.

Instrumentation and Collection of Data

       The  network stations in Lake Michigan were oriented in an east-
west line across the  Lake  and were  spaced approximately 32 km apart,
see Figure 9-1 •
                                   297

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                                                  H
     E   A  E   A
    +  +  +
27  28  29 30  31
+  Current, Wind, Temperature
o  Current, Wind
•  Current, Temperature
   1963
   1964
   1963, 1964
   Current  & Temperature
   1963  8 1964, Wind 1963
   Current  a Temperature
   1963  a 1964, Wind 1964
           SCALE
         0      25 MILES
                     A
                     B
                     C

                     D
                                     40 KILOMETERS
                                GREAT LAKES -  ILLINOIS
                                 RIVER  BASINS PROJECT
                             LAKE  MICHIGAN
                                 NETWORK  STATIONS
                               U S DEPARTMENT OF THE INTERIOR
                             FEDERAL WATER PCL LUTION CONTROL ADMIN.
                             Great Lakes Region        Chicago,Illinois
                   298
                         FIGURE 9- I

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                              TABLE 9-1




                       LAKE MICHIGAN WIND DATA
STA-
TION
01
Ok
05
05
07
08
09
10
13
15
15
17
18
20
20
27
28
30
37
4o
41
47
48
54
61
62
DEPTH-
HEIGHT
METERS
003
003
003
003
003
003
003
003
003
003
003
003
003
003
003
003
003
003
003
003
003
003
003
003
003
003
LATITUDE
4l°48.o'
42°01.0'
4l°59.0'
4l°59.0'
42°45 . 0 '
42°23.0'
42°23.0'
42°23.0'
42°45.0'
42°44.0'
42°44.0'
43°o8.0'
43°08.0'
43°08.0-
43°o8.0'
44°03.0'
44°04.5'
44°04.0'
44°50.0'
44043. 0'
44°39.0'
45°22.0'
45°12.0'
45°48.5'
45°47.0'
Muskegon
LONGITUDE
87°21.0'
87°20.0'
87°00.0'
87°00.0'
87°45.0'
87°25.0'
86°59.0'
86°38.0'
87°22.0'
86035-0'
86°35.0'
87°5l.0f
87°24.5'
86°35.0'
86°35.0'
87°33.0'
87°14.5'
86°48.0'
87°09.0'
86°3l.O'
86°20.0'
86°14.0'
86°02.0'
84°44.5'
86°47.0'
Tower Buoy
FILM NO
200-
038
334
037
333
346
066
067
070
069
068
337
338
170
141
339
340
341
342
106
345
169
095
086
081
076
371
DATE IN
07/24/63
06/22/64
08/08/63
05/12/64
04/10/64
07/30/63
08/18/63
08/16/63
07/31/63
08/05/63
05/11/64
04/09/64
07/16/63
08/04/63
05/10/64
04/23/64
04/23/64
04/19/64
10/06/63
04/19/64
08/22/63
10/04/63
10/04/63
09/24/63
09/23/63
07/22/64
TIME
CST
1350
1740
1145
1043
1410
1750
1330
1045
1330
1900
1005
0830
1500
1330
1025
1020
1400
0725
2035
1515
1000
1430
1120
1510
1310
1155
DATE OUT
09/04/63
07/06/64
08/26/63
07/06/64
06/16/64
10/16/63
10/17/63
10/17/63
10/18/63
10/17/63
07/05/64
07/09/64
11/10/63
11/07/63
07/05/64
07/10/64
07/10/64
07/04/64
10/29/63
07/03/64
11/05/63
10/31/63
10/25/63
10/30/63
10/29/63
09/24/64
TIME
CST
0900*
1640
1000*
0855
1300
1100
1035
0805
1900
1400
1105
1225
1115
1245
0745
0700
0757
0925
1005
1530
1325
1645
0305
1935
1625
1800
*Estimated
                                  299

-------
                         TABLE 9-1 (Continued)




                        LAKE MICHIGAN WIND DATA
STA-
TION
01

Ok
05
05
07
08
09
10
13
15
15

17
18
20
20
27
28
30
37
40
M
47
48
54
61
62
COMPUTED
TIME
INTERVAL
BETWEEN
RECORDS
20.02

19.90


20.00
19.16
20.01
20.01
20.02
19.99
19.98



20.00
20.02
20.02
20.00
20.03
20.03
20.00
20.01
20.00
20.01
20.02
20.79
20.00
20.00
20.00
SPEED
SCATTER
EST. OF 1%
07.0

00.0
03.0
05.0
50.0
00.0
04.0
03.0
05.0

00.0

07.0
00.0
00.0
02. 0
05.0
25.0
43.0
02.0
20.0
02.0
04.0
01.0
o4.o
10.0
•••»•*•»
% VANE
READINGS
DIFFER BY
30° 45°
MMMIM

00.4
— -
02.9
— —
03.5
02.9
01.9
02.6
02.5
01.3

00.1
06.0
00.3
01.6
01.7
02.3
03-7
02.6
02.6
01.4
01.5
02.4
02.1
01.9

— —

— — — —
— —
• •»<»••
•••»•••»
_•»•»•
»*.
•»•»<»•»
— —
• •»•»•»
— _

•»•»•»•»
03.0


— —
M — —
— —
— -
— —
— _ — —
— — — —
— — — —
— — — —

— —
REMARKS
Station broke loose, recovered
data.
Estimated time recovered.
Speed* too high, recomputed.
Record valid only to 6/16/64, 1300






Short record, light struck unknown
period.





Speeds too high.
Speeds too high.

Speeds too high.


Short record - recalculated.

Speeds high.

—— Unknown or not computed.
                                    300

-------
       The network station  la  a  floating  buoy  which  is moored and
untended.  The vind instrument consists of a wind  vane  and  three-cup
anemometer which  are mounted  approximately 3.0 m above the water sur-
face. Subsurface current instrumentation is described in other sections
of this report.

       The three-cup anemometer which  measures wind speed and the wind
vane which measures the wind direction were  developed  at  Woods  Hole
Oceanographic Institution.

       Wind observations as well as current  observations  are recorded
digitally on 16 am  film  in  the form described by Webster (91)   Each
recorded direction gives the  orientation of a given instrument to mag-
netic north and the wind direction relative to the instrument. Thus, it
is possible to determine the true wind direction in spite of the chang-
ing orientation of the buoy system.  For the anemometer each revolution
and tenth revolution of the cups were recorded for a 6-second period in
each 20-minute interval.

       The anemometer sensitivity varies with the direction of the wind
relative to the supporting framework.  The direction calibration of two
of the anemometers used,  as  determined  in the University of Michigan
Department of Meteorology and  Oceanography  wind  tunnel,  is shown in
Figure 9-2.  The essential features of this calibration agree with that
determined at MIT and supplied to  GLIRB Project before the calibration
at the University of Michigan was completed. These instruments, however,
were more sensitive than the manufacturer's specifications stated. That
tested at MIT was less sensitive than the specifications.

       A field comparison of all of the anemometers,  carried  out   at
Cleveland during the winter of 1964-65, showed that the response of all
instruments after a year or two of field use  agreed  with  that of the
instruments  calibrated at the  University of Michigan, within an error
of less than 5 percent, when the wind  came  from  a  direction  nearly
opposite to the vertical support.  This was true even of instruments in
which the cup shaft had been bent,  presumably  as  the  result of wave
damage.

       Directional calibration is readily reproducible to within 5 per-
cent.  Thus, corrections may be applied if the  wind direction relative
to the buoy is known with sufficient accuracy.

       The magnitude of the calibration problem was not fully recognized
until the summer of 1964 and  the angle  between  anemometer  and  buoy
framework needed to correct the earlier data, was not recorded.  In the
summer  of 1964 a vane was added to the buoy stations, to keep the ane-
mometer oriented in a favorable direction most of the time (Figure 9-3).
                                   301

-------
 Tunnel Speed: 5  Meters per Second
   <#°°
<*,
 "00
                                                                              «"3 00
                                                   GREAT  LAKES —  ILLINOIS
                                                    RIVER  BASINS  PROJECT
                                              CALIBRATIONOF GEODYNE ANEMOMETER
                                                WITH RESPONSE AS A FUNCTION OF
                                              DIRECTION OF SUPPORTING FRAMEWORK
                                                  U S DEPARTMENT Of "> *f "Ml ER.<',"
                                              FEDERAL WATER POLLUTiON CONTOQl
                                              GreaT Lakes Region           •""ic'.iji. ^Mine's
302
                                                                            9-2

-------
ALUMINUM PIPE.I-lA"
1.66 O.D. X .140 WALL
LENGTH AS REQUIRED
           FIN
    9 6
12'0"
       BATTERY CASE
                       U.S. GOVERNMENT  PROPERTY
                              KEEP  OFF
                                                        ANEMOMETER
                                                        NAVIGATION LIGHT
                                                        WIND RECORDER
    2'6"
                                 8'0" DIA.
       I  INCH =  2.54 CENTIMETERS
GREAT LAKES  —  ILLINOIS
 RIVER BASINS PROJECT
                                                 INSTRUMENT BUOY
                                                    TOROIDAL SHAPE
                                                     NOT TO SCALE
                                             U S DEPARTMENT OF THt INTERIOR
                                          FEDERAL WATER POLLUTION CONTROL ADMIN ,
                                          Great Lakes Region           Chicago,Illinois
                            303
                     r.GuRE  9-3

-------
       The wind vane is more responsive than necessary for this type of
study.  However,  much of the overshooting of the vane proper is elimi-
nated by an oil-damped vane follower.  The dynamic response of the full
wind vane system has not been investigated.

       The wind speed is recorded on  photographic film  as a series of
light pulses spaced according to the speed of the anemometer.  The wind
direction  is recorded as vane and compass position In Gray Binary code
transmitted to the camera by fiber optic light pipes.  The photographic
film  was  developed and transferred from the film to a low density IBM
compatible magnetic tape in  binary format.  The data from the magnetic
tape were  programmed by computer in three forms:  6-hour   averages of
wind directions and speeds,  2-hour  envelopes,  and  histograms.   The
averages for each 6 hours  (0, 6, 12, and 18 hours)  were  tabulated to
include the number of observations, direction and speed,  and the coef-
ficient of variation of speed, Figure 9-k.

       Two directional readings were  obtained  for  each observational
interval and  the arithmetic mean of these two was accepted as the true
direction.  This process was adopted to reduce the effect of vane over-
shoot.  A detailed examination  of  data samples  from several stations
indicated that the  error due to overshoot was  insignificant  about 90
percent of the time and that this simple  correction was sufficient for
most overshoot errors.

       Average winds were used rather than  instantaneous winds because
it is believed  that  average  winds  are more representative of actual
conditions over a period of time.  The  average  values considered were
for periods  to  conform  to  the  synoptic interval on weather charts.
These values were obtained by converting  velocity  vectors  into  com-
ponents along the x and y axes,  averaging  each  component separately,
and computing the vector resultant of these average components.

       Two-hour envelopes as a rule smooth out enough of the small-scale
features to make the dominant features  of the wind  field discernible.
The 2-hour envelopes  are obtained by plotting  the maximim and minimum
values  of wind speed and accompanying direction for each 2-hour period
being considered, Figure 9-5.

       The histograms  are two-dimensional  distributions of wind speed
versus wind direction for the total number of observations for an entire
month, Table 9-^.   From these values prevailing direction expressed in
terms of net  flow can be calculated by taking the algebraic sum of the
products of wind speed and  number  of periods  it occurs and that of a
wind blowing in the opposite direction.
                                  304

-------
                E
                ro
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                                              305
                                                                                                              9-4

-------

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-------
Climatology of Surface Pressures and Winds

       The day-to-day wind*, when combined Into averages, give the cli-
matology of the wind field over Lake Michigan and the other Great Lakes.
The winds, Instantaneous and averages,  respond to the overall pressure
field of the area.  At this point it is well to discuss the climatology
of the pressure and wind field in the Lake Michigan and Great Lakes area
before presenting the results of the wind study.

       Lake Michigan and the Great Lakes  In general lie in the path of
several of the major storm tracks that cross the United States. The low
pressure areas that follow these tracks are more frequent in the winter
than the summer,  but traverse the Great Lakes area at all times of the
year.

       As a rule,  low  pressure  areas that cross Lake Michigan follow
two main paths.   Those that develop in Colorado and the northern Rocky
Mountains move northeastward or eastward across southern Lake Michigan.
They are the winter-time lows. Those that form in the Canadian province
of Alberta  move  southeastward  across the  northern United States and
recurve eastward in the Great Lakes area.   Lows that follow this track
frequently cross Northern Lake Michigan and occur in the summer as well
as the winter.

       The Great Lakes not only  lie in the path  of  some of the major
storm tracks that cross the United States  but  also  contribute to the
intensification  of low pressure areas that cross the region.  At times
lows Intensify rapidly as  they  enter  the western Great Lakes area of
Lake Superior and Lake Michigan. Intensification occurs during the fall
and winter when the water in the Great Lakes is warm in comparison with
the very cold  arctic  or polar  air that may follow Immediately behind
the center of the low.   The intensification of the low may be so great
that a major storm results.

       Because of the great contrast in the fall and winter between the
warm water of the Great  Lakes  and  the  cold arctic or polar air that
crosses  the bodies of warm water, low pressure areas may develop occa-
sionally In the Great Lakes area. The probability of actual development
is not great unless upper air conditions are right for the formation of
the surface  low.   At  any  rate most of the lows that cross the Great
Lakes develop farther to the west rather than over the Lakes than selves.

       The prevailing  winds  over  the  Lake Michigan area reflect the
average pressure field.  The storm tracks that cross the Lake influence
the average  pressure field in such a way that the prevailing winds are
from the southwest through west.
                                  307

-------
Data Analysis and Discussion

       ID analyzing the Lake Michigan wind data, the following procedure
was followed:

       1.  Buoy vinde were  plotted  on  the  printout  charts  of Lake
Michigan.

       2.  Ship observations including  ship  winds for the standard 6-
hourly synoptic times (OOC, 06C, 12C, and l8C) were plotted.

       3.  The observations  for  surrounding  land  stations  for  the
standard 6-hourly synoptic times were plotted on the sane charts.

       k,  A pressure and  frontal  analysis  was  made on the chart so
that geostrophic winds could be calculated from the  pressure gradient.
Strictly speaking, the gradient wind should be calculated,  but for the
purpose of this study it was assumed that the gradient wind approximates
the geostrophic wind for the Lake Michigan area because spacing between
observation points is too great to make a detailed analysis of the wind
field to determine if there is a  pronounced  curvature  in the stream-
lines.

       The geostrophic wind is defined  as a wind that  exists In fric-
tionless straight  flow when  the  pressure-gradient force balances the
Coriolis force;  in other words, a wind that flows parallel to straight
isobars.

       The gradient wind is the counterpart  of the geostrophic wind in
curved flow when  the  pressure-gradient  force  balances  the Coriolis
force and centrifugal force; in other words, a wind that flows parallel
to curved isobars or streamlines.

       The following discussion of results  refers  to the  analysis of
data for the period which has been most thoroughly studied — September
1963.

       The computer was  used to prepare printout  charts with the wind
data entered on them.   A  sample  chart  including a few merchant ship
observations is shown in Figure 9-6.  Agreement between the wind direc-
tions observed  from  the  buoy stations and those obtained from nearby
vessels  was excellent; differences in direction are usually in a range
of 10 to 20 degrees.   The fact that the ship observations are taken at
a higher  elevation than the buoy observations, and that the buoy winds
are 6-hour averages,  explains the lower speed values of the buoy winds
as compared to ship winds.
                                  308

-------
Printout   chart  with  buoy   winds,  ship  winds,  and
observations  at  land  stations  for  06 C  Septem-
ber  2,  1963.
                           62
LEGEND
NNDD
 ddjvv
  NN
  DD
  dd
  vv
                                             SCALE
                                          0         40 MILES
                                           r i     ,i
                                          0        60 KILOMETERS
       Buoy Station
       Number of Observations
       Coefficient of Variation of Speed
       Wind Direction
       Wind Speed
                                     64194
TT PPP
wwo     Ship Station
ddj vv
TT PPP
wwo     Land  Station
GREAT LAKES- ILLINOIS
 RIVER  BASINS PROJECT
                                       LAKE  MICHIGAN  PRINTOUT
                                       US DEPARTMENT OF THE INTERIOR
                                  FEDERAL WATER POLLUTION CONTROL ADMIN.
                                  Great Lakes Region         Chicago ,Illinois
                          309
                                                        F1GURE9-6

-------
       In the investigation of  the relationship of buoy and ship winds
to geostrophic winds, data were examined for station 18 in the southern
basin of Lake Michigan, and for station hi in the northern basin.  Ship
observations were selected for  points  as  close to these  stations as
possible.   For each of the two stations the data were divided into two
groups according to stability of the air mass. For this purpose, an air
mass with a lapse rate less than 6°C between water surface and the 850-
millibar  (mb) was considered to be stable; and an air mass with a cor-
responding lapse rate of 6°C or  more was  classified as unstable.  For
estimating the lapse rates,  the surface temperature was  assumed to be
approximated by surface water temperatures obtained from municipal water
intake records;  temperature at the 850-mb  level was interpolated from
meteorological records.  The 850-mb level is  approximately  k,000 feet
above the Lake.

       Table 9-2  shows the average ratios of buoy and ship wind speeds
to geostrophic winds over Lake Michigan for the month of September 1963-
In all cases  shown, the  ratios are less at station kl than at station
18, for reasons  that have not been  determined.  The ratios are larger
for a steep lapse than for a small rate.  This is to be expected, since
there is more mixing between  the lower and middle layers of the atmos-
phere in unstable than in stable situations.  The range of values shown
for steep lapse rates is 0.529 to 0.771, and for small lapse rates 0.1*81
to 0.585.

       Table 9-3 shows the average clockwise deviation of buoy and ship
wind directions from geostrophic wind directions over Lake Michigan for
the same period.  In all  cases  shown,  the deviation at station kl is
consistently  greater than at station 18.  For steep  lapse  rates  the
deviation of buoy and  ship winds  from geostrophic winds  is less than
"or small lapse rates.  The  range  of  values  shown for steep rates is
    to 1*2° and for small lapse rates 39° to 57°, respectively.
       Statistical tests were made to determine whether  the variations
in the relationship between observed and geostrophic winds for stations
18 and 1*1 and for  small  and  steep lapse rates were significant.  The
tests were inconclusive for the difference between stations, but showed
that there is a significant  difference  in  the  wind relationship for
small and steep lapse rates.

       Charts for the  current  records,  constructed on the same basis
and for the same time periods as the wind charts, are not very enlight-
ening as to relationship of  Lake  currents  to concomitant winds.  The
rotary currents  shown in Figure 9-7  (plotted from 6-hour means)  fre-
quently  dominate the record,  but the phase of  rotation may vary with
depth at one station and with horizontal distance at one depth.  Numer-
ical filters have been used in an  attempt  to eliminate  this inertial
                                  310

-------
                              TABLE 9-2

                     RATIO (F BUOY AND SHIP WIND
                       TO GEOSTROPHIC WIND SPEEDS OVER
                     LAKE MICHIGAN FOR SEPT. 1963
     STEEP LAPSE RATE
                            SMALL LAPSE RATE
Buoy
Ship
                      Buoy
           Ship
#18
0.629   0.529
#18
0.771
        0.716
                      #18
0.385
#18
0.589
0.523
                              TABLE 9-3

               AVERAGE DEVIATION OF BUOY AND SHIP WIND
           DIRECTIONS FROM GEOSTROPHIC WIND DIRECTIONS OVER
                     LAKE MICHIGAN FOR SEPT. 1963
     STEEP LAPSE RATE
                            SMALL LAPSE RATE
Buoy
Ship
                      Buoy
#18
        26°
#18
17°
           Ship
                      #18
                      42°
57°
#18
39°
                                  311

-------
                        TABLE 9-4




              WINDS - STATION 5, AUGUST 1963




                        HISTOGRAM
DIRECTION
IN DEGREES
0
30
60
90
120
150
180
210
240
270
300
330

7
51
71
67
105
130
121
138
163
103
78
38
69
SPEED
19
81
91
40
32
15
21
44
51
32
14
10
18
AVERAGE IN KNOTS
32
30
15
0
5
1
0
7
5
1
1
5
14
45
6
0
1
1
0
0
1
1
0
0
4
4
58
0
0
0
1
1
1
0
2
0
0
0
0
NUMBER
168
177
108
144
147
143
190
222
136
93
57
105
TOTALS
1,134
449
84
18
1,690
                            312

-------
STATION  8   DEPTH 10  METERS
               AUG. 1-9,1963
320
280
240
LAKE MICHIGAN
                       SCALE
                   0      5      10 MILES
                    I I  I I I  I I  I I  I I
                    I    I    I     I
                   0    5    10   15 KILOMETERS
                           120    160   200
            40     80
           cm/sec
                            GREAT LAKES — ILLINOIS
                            RIVER BASINS PROJECT
                            CURRENT TRAJECTORIES
                U S DEPARTMENT OF THE INTERIOR
             FEDERAL WATER POLLUTION CONTROL ADMIN
             Grtat Lokcs Rtgion       Chicogo,Illinois
                  313
                            FtGURE 9-7

-------
period from a few short samples of data, but further study is needed to
understand the significant features of the filtered data.

Lake Breeze Phenomenon

       At times the lake breeze  phenomenon  is  pronounced  along  the
shores of Lake Michigan.  The wind data obtained from the buoys on Lake
Michigan help to clarify some details of the phenomenon.  An example of
the lake breeze is given here for August 20 and 21, 1963. On those days
a large weak high was centered over the Ohio Valley with a weak pressure
gradient extending  over the southern  part of Lake Michigan,  northern
Illinois, southern Wisconsin, and lower Michigan.   Figures 9-8 and 9-9
show the weather charts for 12C (noon, Central Standard Time) August 20
and 21.

       At 12C on both days,  temperatures at the land stations near the
southern Lake Michigan shores ranged from around T2°F to 85°F. The Lake
temperature on August 20 was 63°F  at Chicago and 50°F at Muskegon.  On
August 21, Lake temperature was 56°F at both Chicago and Muskegon. With
the Lake cooler  than  land  the air in contact with the water would be
expected to be cooler than the air over land, thus making  ideal condi-
tions for a lake br-:eze.

       Two-hour envelopes of  wind direction  are presented  in Figures
9-10 and 9-11  for stations 8 and 18 on August 20 and 21.  At station 8
on the envelope for the first day,  the wind is blowing from the south-
west through west until  10 o'clock.  Then it shifts  to southeast  and
remains from that direction  until 22C  when it shifts to the southwest
and west for the rest of the night. The cycle i.s repeated on the second
day but the shift baric to the southwest begins at about l8C rather than
22C.  Station 18,  Figure 9-11,  shows  the  same type of cycle of wind
directions as station 8 for the two days.

       The relationship between geostrophic and  observed winds gives a
basis for a method of forecasting winds over the Great Lakes.  Unfortu-
nately, the relationship  between  winds  and  lake  currents is not as
straightforward,

A Comparison of Lake Wind to Land Wind

       Wind data at Lake station 8 were  compared  to those from Midway
Airport, Chicago,  Illinois for the month of  September 1963.  Six-hour
average winds for  the  two  locations  were compared  over the 1-month
period.

       Figure 9-12 shows the directional relationship  between the sta-
tions.  Disregarding  occasional  periods of calm,  the absolute  value
(without  regard  to  whether  clockwise  or  counterclockwise)  of the

-------
140°      I2O°    IOO°    80
                             GREAT  LAKES — ILLINOIS
                               RIVER BASINS  PROJECT
                          SURFACE WEATHER MAP AT 1200 CST.
                           TAKEN FROM DAILY WEATHER MAP
                         U.S.WEATHER BUREAU AUGUST 20,1963
                            U S  H PAH IMf N r of TMf ir\,Tf RIQR
                        Ff^EHAL WA'tR POL _b' 'ON CONTROL ADWIN
                        Great >_an«»
                                                 FIGURE 9-8

-------
          140°     120°   100°    80
I   I.I	I   I Milei
    SCALE
                                       GREAT LAKES 	 ILLINOIS
                                        RIVER BASINS  PROJECT
                                   SURFACE WEATHER MAP AT 1200 C ST.
                                    TAKEN FROM DAILY WEATHER MAP
                                   U.S WEATHER BUREAU AUGUST 2 1,1963
                                      U S DEPARTMENT Of THE INT ERluR
                                  FEDERAL WATER POILU1ION CONTROL  ADMIN
                                  Great Lakes Region           '"hicugo lmno;S
                                                           FIGURE 9-9

-------
TWO  HOUR  SPEED-ANGLE  ENVELOPE
                                                                AUGUST 20-31,1963
         FILM- 20066   STA    8    DEPTH   0     TIME  INTERVAL - 2O
                      ANGLE  IN   DEGREES
.0         72.0        144.0         216.0
                                                           288.0
                                                                I
                                                                        360.0
H
o
UJ
p
    oo
    02
    O4
    06
    08
    10
    12
    14
    16
    18
    20
    22
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    08
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    12
    14
    16
    18
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                                             o
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                              o    o
         	  AVERAGE CURVE
                                317
                                                  GREAT  LAKES — ILLINOIS
                                                   RIVER  BASINS  PROJECT
                                             TWO HOUR SPEED-ANGLE ENVELOPE
                                        U S DEPARTMENT OF THF iNTERulR
                                    FEDERAL WATER POLLUTION CONTROL Ai)V^
                                    Great Loket Region           Otc<;g • '. no i
                                                             F.Gu^'E 9-10

-------
TWO  HOUR  SPEED-ANGLE  ENVELOPE
                                                                AUGUST 20-21,1963
O
UJ
5
oo
02
O4
06
oe
10
12
14
16
18
ZO
22
00
02
04
06
08
10
12
14
16
18
20
22
         FILM- 20170   STA.   18    DEPTH   0     TIME   INTERVAL - 20
                              ANGLE IN  DEGREES

                   72.0         144.0         2160
                   •  •  I	I	I
                                                       288 .0
360.0
                                                                         I
                                                    _o
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                                                          .'
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                              /  o
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                            O \ O
                 AVERAGE CURVE
                                                  GREAT  LAKES — ILLINOIS
                                                   RIVER  BASINS  PROJECT
                                             TWO HOUR SPEED-ANGLE ENVELOPE
                                                 U S DEPARTMENT OF THE INTERIOR
                                             FEDERAL WATER POLLUTION CONTROL AOMIN
                                             Great Lofces Region           Chicago I., nms
                                318
                                                                  FIGURE 9-11

-------
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-------
deviations averaged 32 degrees.  The  algebraic average deviation, con-
sidering a  clockwise  deviation of lake wind to land wind as positive,
was minus 17 degrees; that is,  on the average  the lake wind direction
was deflected  counterclockwise  from that  over Midway  Airport.  As a
further indication  of prevailing conditions during the month examined,
the deviation of lake  wind to land  wind was either  zero or  counter-
clockwise some 80 percent of the time.

       Wind speeds during September were higher over the Lake than over
land, as expected for summer and fall. The reverse is probably true for
late winter and spring, but no Lake records are available.  The average
wind speed at Midway was 16.0 km/hr (lO.O mph)  and at station 8 it was
19.6 km/hr (12.1 mph), or IT percent higher over the Lake.  Figure 9-13
indicates close  agreement in the lower speed to about 10 km/hr and the
difference widens until kO km/hr  where  there  appears  to be a break.
There are too few numbers beyond 40 km to estimate the trend.

       Although winds do not alter current  directions in mid-lake dur-
ing the summer period,  there is a relationship  between wind speed and
increased current speeds, even at great depths (Verber, 89).

Wind Spectra

       This section covers the wind spectra computed from Lake Michigan
wind records collected  during the summers of 1963 and 1964.  Table 9-5
summarizes the wind spectra analyzed.   In  this table each station has
listed:  the film number of the record,  the length of each record, the
orientation of the axis  for  the velocity component   computation, and
whether or not the station is  near the shore.   Speed spectra calcula-
lations were not made after test cases showed that estimates were unreli-
able.

       The following  stations from the summer of 1963 showed a diurnal
peak around 2k hr  in one or both of the velocity components:  Stations
1, 8, 10, 13, 15,  20,  and kl.   Stations 5 and 30 have no significant
peaks.  Station ko (Summer 1964) has a diurnal peak.

       The semidiurnal oscillation  is evident in records from stations
8, 10, 13, 15, 20, 30, 40, and kl. Figure 9-14, station 13, illustrates
an example of wind spectra.

       Long period oscillations around 115 hrs are evident and may rep-
resent some kind  of average  frequency of meteorological disturbances.
Whether they are physically present is still unknown, but they fit with
the energy peaks.
                                  320

-------
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                                                                       F GuRF 9 -

-------
           TABLE 9-5




LAKE MICHIGAN WIND SPECTRA DATA
STA-
TION
01
05
08
10
13
15
20
30
4o
41
FILM NO.
200-
038
333
066
070
069
068
141
342
3^5
169
DATES OF VELOCITY
SPECTRAL RECORDS SPECTRA AXIS
ORIENTATION NEARSHORE
START END (Y AXIS) STATION
07/24/63
05/12/64
07/30/63
08/16/63
07/31/63
08/05/63
08/04/63
04/19/64
04/19/64
08/22/63
09/04/63
07/06/64
10/16/63
10/17/63
10/18/63
10/17/63
11/07/63
07/04/64
07/03/64
11/05/63
0-180
30-210
30-210
170-350
160-340
0-180
0-180
0-180
30-210
0-180 x
OFFSHORE
STATION
X
X
X
X
X
X
X
X
X

              322

-------
           100
HOURS
20    16.7
                      Y  AXIS -160° - 340°
10
                                                                             84
          100
     NO. OF  OBSERVATIONS-  5658
                                         167
                                                   GREAT  LAKES — ILLINOIS
                                                    RIVER  BASINS  PROJECT
                   WIND   -  STA. 13
               SPECTRA   OF  COMPONENTS

                    LAKE  MICHIGAN
               U S DEPARTMENT OF THE INTERlOP
           FEDERAL WATER POLLUTION CONTROL  AuMIN
           Greot Lakes Region           Chicogo ! mo s
                                                                       FIGURE 9- 14

-------
Summary

       The meteorological studies  have  revealed relationships between
geostrophic winds and observed vinds over Lake  Michigan;  and  between
winds over the Lake and winds at adjacent land stations.  This provides
a basis  for  forecasting  the  speed  and direction of wind at desired
specific locations over the Lake. Unfortunately this cannot, with pres-
ent knowledge,  be translated into forecasts of water current velocity.
While there is no  doubt that the wind  is  the  primary  force causing
motion of  Lake  Michigan water, the relationship is a complex one, the
water motion being modified by such factors as variations in atmospheric
pressure  on  the  Lake  surface and the earth's rotation.  Once set in
motion by primary wind forces, the water velocity at a particular place
and time will be a function of antecedent conditions perhaps far removed
in time, and will exhibit internal wave patterns corresponding in peri-
odicity to seiches and the Lake's inertia! period.  It is believed that
further study  can  yield a solution which will permit formulation of a
mathematical model incorporating  all of these factors, and make possi-
ble the forecasting of Lake currents.
                                  324

-------
                              CHAPTER 10

                    CORRELATION OF WHO, CURRENT,
                      AMD TB4PERATURE » SUMMER

                                  by

               Clifford H. Mortimer and James L. Verber
       During the Project studies in the sunnier of 1963  the University
of Wisconsin was conducting specific Internal wave studies in the region
between Milwaukee,  Wisconsin and  Muskegon, Michigan.   These studies,
combined with Project studies, shed new light on the relationships among
wind, currents, and temperature.

       At the University of  Wisconsin,  Dr. C. H. Mortimer was given a
"Visiting  Professorship" for the opportunity  to test hypotheses  con-
cerning internal  waves and associated  water movement in  central Lake
Michigan.  This work was  supported by an Office of Naval Research con-
tract, Nonr-1202 (22), and some results of current measurements at mid-
lake anchor  stations  were  outlined in  Chapter 6.  In addition, with
facilities provided by the Grand  Trunk Western Railroad  Company, tem-
perature  distribution was  measured from  the Company's  vessels on 80
crossings  between July Ik and August  30, 1963.  Apart from occasional
gaps due to change of vessel or instrument loss, the 127-km long section
was monitored on consecutive crossings with bathythermograph (BT) casts
every 2 km.

       During the  whole period the thermocline showed  oscillations in
depth, often quite large,  and often  combined with or following strong
upwelling on one shore and downwelling  on the other  shore after  wind
disturbances.  For instance, two major storms, from the north on August
13 and 17  (see Figures 10-5 and 10-6), produced a strong downward tilt
of the thermocline on the  western shore  and  upwelling on the eastern
shore which persisted for several days. The latter storm also generated
internal waves of  large amplitude, illustrated by two consecutive tem-
perature sections in  Figure 10-1.  These  pictures are not, of course,
synoptic,  as the ferries take roughly six hours to cross the Lake; but
the standing nature of the  internal  waves is  made evident in Figures
such as 10-1  by the fact that on consecutive runs the ferries normally
cross the midlake  point  at intervals of about 8 hours, i.e., approxi-
mately one-half of the local  inertial  period (17-55 hours).  Internal
standing waves of near-inertial period should, therefore, show a change
in sign of wave slope near the midlake  position and this was frequently
observed on successive  crossings (Figure lO-l).  The change in sign of
the thermocline slope at about 70 km from Milwaukee suggests that there
was a node  in  that region.   This  is  confirmed  and more strikingly
                                   325

-------
(Mortimer, unpublished,April, 1967)
                                                GREAT LAKES —  ILLINOIS
                                                 RIVER BASINS  PROJECT
                                              TEMPERATURE DISTRIBUTION
                                               BETWEEN MILWAUKEE, WIS.
                                                 AND MUSKEGON.MICH.
    US DEPARTMENT Jr  THf INTL^I •«
FEDERAL WAH K POLLUTION CONT(*GL AuVIN
Great La*«s Region           '"'ucc^-j i ,•*  -
                                                                          10-1

-------
demonstrated in Figure 10-2,  in  which  the 10° isotherm  (representing
approximately thermocline depth) is plotted for nine consecutive cross-
ings over the interval August 19-22.   The  Figure shows a definite and
persistent  node  in  midlake at 66 km from Milwaukee,  with less clear
indications of at least two other nodes. The most likely interpretation
of this Figure is in terms of a combination of transverse  standing waves
of several nodalities, with first and third predominating  and perhaps a
fifth also present.   Odd  nodalities must have been preferred, because
of the way In  which the wind stress tilted the thermocline down on one
shore and up on the other; and the midlake  nodes of each  wave probably
coincided to give the clear picture at 66  km.   Coincidence  elsewhere
would not be expected.

       Having demonstrated the  generation  of a large amplitude trans-
verse standing wave pattern, it will be helpful to recapitulate briefly
Mortimer's 1963 predictions (5^) concerning the nature of  internal waves
in central Lake Michigan, as illustrated in Figures 10-3 and 10-U,  for
rectangular  models  of constant depth, rotating counterclockwise.  The
wave surfaces shown in those Figures can be envisaged, either as a water
surface or as a thermocline interface between two homogeneous layers of
differing density,  in  which  case  the (highly) generalized currents,
associated with the waves, are shown for the lower layer (hypolimnion).
The corresponding  currents in the upper layer will  be exactly opposed
in direction; and the speed ratio will be the inverse of the depth ratio
of the two layers.

       In a narrow channel  (Figure 10-3, upper part)  a Kelvin wave is
dominant, and this is also true near the shore in the other wide-channel
models.  The currents are constrained to run parallel to the shore, and
the response to rotation takes  the form  of an exponential decrease in
wave amplitude and current speed along a line normal to the shore.  For
the internal Kelvin wave case in Lake Michigan, this amplitude falls to
a negligible value 10 km or so away from the  shore.   Internal  Kelvin
waves are,  therefore,  essentially  shorebound.   At greater distances
offshore, where  the constraints of the  boundaries  can   no  longer be
"felt", the response  to  rotation,  in a semi-infinite sea of constant
depth, Figure 10-3, lower part, is a Sverdrup wave, in  which  the wave
crests are horizontal but in  which  the  currents rotate  (clockwise in
the northern hemisphere).

       Lake Michigan, however,  is  bounded; and just as in lakes small
enough for rotational  effects  to be neglected,  seiches  are set up by
wave reflection from opposing shores.  In the special case, only possi-
ble in  an  infinitely  long  channel  (Figure  10-^,  upper part), two
equivalent Sverdrup waves, of  equal amplitude,  traveling in opposite
directions normal to the side of the  channel, produce  a  standing wave
                                  327

-------
             10    2O
kilometres  from Milwaukee  breaKwater
   40     .     80     .    80         100

A
1
10 	
Nodes at:



DEPTH OF X
	

7
it
!
•'
D* ISOTHERM
B
I
66 km
         \
        i  V
                   LAKE MICHIGAN 1963 TEMPERATURE DISTRIBUTION, 'C,
                      IN THE MILWAUKEE-MUSKEGON SECTION
                                                                        120  127
                             LEGEND

                     A-Sta l7,ll.5Km.North of Ferry
                     Track
                     B-MV'tisco"l2Km.Northof Ferry
                     Track
                     C- Sta. 20,6 5 Km South of Ferry
                     Track
(Mortimer unpublished, Apr i I, I967)
                             GREAT  LAKES  —  ILLINOIS
                              RIVER  BASINS PROJECT
                         DISTRIBUTION of 10° ISOTHERM
                            MILWAUKEE to MUSKEGON
                            U S DEPARTMENT OF THE INTERIOR
                       FEDERAL WATER POLLUTION CONTROL  ADMIN
                       Great Lak«» Region            Chicago.li.mo.s
                                                                             FIGURE 10-2

-------
                                           (A)
                                             o
              LEGEND
     A.- Qualitative Representation of A
        Single Kelvin Wave
     B.- Qualitative Representation of Part
        of A Semi-Infinite Rotating Sea with
        A Kelvin Wave
Affer Mortimer, 1963(54)
     GREAT  LAKES  •—  ILLINOIS
       RIVER  BASINS PROJECT
 QUALITATIVE REPRESENTATION  of
  KELVIN and SVERDRUP WAVES
    U S DEPARTMENT OF THf !NT ERIOP
FEDERAL WATER POLLUTION CONTROL ADViN
Great LaKci Region            •"tucfjgr; I, ni' c,
                                   329
                          FIGURE 10-3

-------
                                                               *»VE
                                                         (B)
                 LEGEND

         A.-Quolitotive Representation of
            Transverse Standing Waves
            with Sverdrup and Kelvin Waves

         B.- Qualitative Representation of
            Standing Poincare Waves
After Mortimer, 1963 (54)
     GREAT  LAKES — ILLINOIS
       RIVER  BASINS  PROJECT
  TRANSVERSE STANDING.KELVIN,
 SVERDRUP and POINCARE WAVES
    U S DEPARTMENT OF THE
FEDERAL WATER POLLUTION CONTROL
Great Lakes Region            Chicago I iinu s
                                330
                          r.GURE  10-4

-------
                      WIND  AT STATION  18  —  LAKE  MICHIGAN
 30
   NW»SE
           SE
           SE
       SW
                     NW
     SW»SE
                          AUG

                           5
                                    W+NE
                                   SE
                                                  NE
                                                      10
                                  NE
                                  -SW
                                                                 12
                                                                     IW
                                                                            14
                                            N»-S
                                                                                  15
                                      SW*SE
2O
    SE
15


10-
          -SW
      WNW
                     MILWAUKEi:
                          SSW
                            J1L
           ssw-
            sw
                            NNE
SSE —
ESE
                                               NNE
                                                   SW
                                      SSE -
                                      SWi
                                         NW
                                 NNW-
                                  NNE
                           SE
2O-
15-
    NW-
   WNW
 0-
S-
  SSW
      ssw-
      NW
            GRANDRAPIDS
 NW-
MNW
            11
ssw-
wsw
                           I
wsw
       NW
NW-W
                WNW
W
                WSW-
                WNW
SSE-
SSW
                                                                     WSV
                                                                     WNWI
                                NNW
 W-
WSW
                                                              II
20-
5 •
        SE-iSW
0-
      W-NW
 CHICAGO -

       SW
     MIDWAY

       SW  NE-E
                                                NE
                                             NE
                                      NNW-
                                        E
                                                            II
                                       SW
                                       NW-
                                       NNE
                                 NNE
                          W-NW
                                                                                    I-
                    CHICAGO -
5-
   IMNE
         SSE
O-
      WNW
       i
                      O'HAR
                                                                ssw
                            NNE
                                                NE
                                                                        NNE
                                                                           NNE
     123456789


                                  AUGU ST   1963

  SPEED  IN  KNOTS

  LAKE  WIND -  2HOUR ENVELOPES

  LAND  WIND -  HOURLY

  ONLY  SPEEDS  OVER 9  KNOTS WERE

  CONSIDERED AND  PLCkTTED ON  A  SQUARE - LAW

  SCALE  TO APPROXIMATE   WIND  STRESS
                                              10   II     12   13     14   15
                                             GREAT LAKES  — ILLINOIS
                                              RIVER BASINS PROJECT
                                               COMPARISON  OF  LAKE
                                             .AND  LAND  WIND  SPEEDS
                                                    U S DEPARTMENT OF THf  INTERIOR

                                                FEDERAL WATER POLLUTION CONTROL AuMiN

                                                Great Lakes Region           Oic< :p l> r-•,
                                    331
                                                                 FIGURE 10-5

-------
                     WIND  AT STATION  18  —  LAKE  MICHIGAN
   S-SE
30
         17
               18
           19
 AUG

 20
21
22
                                          23
                                                24
                                            25
                                                 26
                                       27
                                                            28
                                                                       30
         N-
         NE
  SW<
  SE
               SE
          SE
                         SW
           SW-SE
             NE|

          S»NE
                                                     NE
                                                      SE -- SW
                                                                               W-»-NE
15
2O


15

10-

20-


15-


10


20-


15


10-


5-


0-
   SSWi
              ENE-
              ESE
           MILV
          NE-E
AUKCfc
ESE-
 SE
     sw-
     ssw
     sw-
     NNE
NE '
      ESE
SSE
-SE
WSW
         WSW
         NW
                    GRAM
               0 RAPIDS
                wsw-
                 w
                          ll Illll
      wsw-
       w
     wsw-
     WNW
    wsw-
      w
          NE-E
ENE-
ESE
     SSE-
     WNW
      W-
     WSW
      NW -
     WNW
                    CHICAGO -
         NE
                    MIDWAY
                      W
            SW
                                      It
           SW
                                      NE
                                            NE
                                                  ll l
                                                      SSW
                                       JJ/I
                                                           - SW
                                                   NW
                                            il
                                                                       N W
                    CHICAGO -
   SSE
NNE
                     O'HAR
                                      NE -  ENE
                                                   mi ii
                                                  WNW
                                                                                NW .
                                                                        mi
    16   17    18     19    20   21     22   23    24   25   26    27    28   29    30

                                 AUGU ST    1963
  SPEED IN  KNOTS
  LAKE  WIND-2HOUR ENVELOPES
  LAND  WIND- HOURLY
  ONLY  SPEEDS OVER  9  KNOTS  WERE
  CONSIDERED AND PLOTTED ON A  SQUARE - LAW
  SCALE TO APPROXIMATE  WIND  STRESS
                                            GREAT  LAKES —  ILLINOIS
                                             RIVER  BASINS  PROJECT
                                             COMPARISON  OF LAKE
                                            AND  LAND  WIND SPEEDS
                                                    U S DEPARTMENT OF THE INTERiOR
                                               FEDERAL WATER POLLUTION CONTROL AuMiN
                                               Great Lake* Region           Chicc 30 i. no s
                                    332
                                                                FIGURE 10-6

-------
system with horizontal  wave  crests  running  along  the length of the
channel.   Because  of the boundary condition, that the transverse com-
ponent of flow  must always be zero at the shores, only a discrete num-
ber of waves can develop across the channel.

       If the channel is not infinitely long but has ends, then Sverdrup
wave reflection  will occur at these boundaries also; and a second dis-
crete set of standing waves will be set up, this time along the channel
and again meeting the boundary condition  that  there  shall be no flow
normal to the ends.   The combination of this longitudinal set with the
transverse set results in a cellular pattern of standing waves (Poincare
waves), and  the  dimensions  of  the  cells are determined by the wave
lengths in the longitudinal and  transverse  directions.   A portion of
such a system, representing the central part of Lake Michigan, is shown
in the lower part of Figure 10-4.  This presents a model of thermocline
topography and also indicates  part  of  a  long shorebound Kelvin wave
close to each "shore".  A and B represent water  intakes,  one of which
is above the "thermocline", i.e., in the warm upper layer while the one
on the opposite shore is in the lower cold layer—a common situation in
Lake Michigan.

       Figure 10-4 depicts  a system with a rather high number of nodes
across the channel,  whereas  Figure 10-2  suggested  that  the  number
(normally an odd number) is small; 1, 3, or 5,  perhaps in combination.
If,  as  seems  likely,  the  rate of frictional damping increases with
nodality, the uninodal pattern may be expected to persist longest after
a wind disturbance.  This will be  particularly  true  of the currents.
With decrease in nodality,  more of the internal wave energy appears in
kinetic form  (currents) and less as potential energy (thermocline dis-
placement) .

       On the assumption that a  combination of standing Poincare waves
and nearshore  Kelvin waves is an acceptable  model  for  central  Lake
Michigan, the relationships between thermocline displacements,  current
direction,  and  speed are  summarized  for the uninodal case in Figure
10-15.   For  the elucidation of these relationships we are indebted to
Dr. M. A. Johnson of the  National Institute for Oceanography, Wormley,
Surrey, England.  For conditions near the ends of Lake Michigan, inter-
pretation in terms of models other than rectangular may provide abetter
fit  with  the  observations;  for  instance,  a  semicircular  portion
(involving Bessel functions) closing the end  of  a long channel, or an
elliptical basin of high eccentricity (involving Mathieu functions).

       The observations on  the Mllwaukee-Muskegon section coincided in
time (summer 1963) with the maximum deployment of the Project's record-
ing instruments in the Lake.  It is,  therefore,  worthwhile to see how
far each set of observations can aid in the interpretation of the other.
                                  333

-------
The positions of the stations considered,  for  which  both temperature
and current data were available and  which were closest to the railroad
ferry track, are given in Table  10-1.   The  stations  were:   17,  M2
(Mortimer's anchor  station), and 20, near the ferry track, and station
15, 49 km to the south of it.

       Local wind observations were provided  by  station 18 (wind data
only) in the form of 2-hourly envelopes of maximum and m-tn-timim readings.
These are compared (Figures 10-5 and 10-6)  with hourly  Weather Bureau
readings of six land stations. In an attempt to represent the magnitude
and timing of the main wind stresses,  wind  speeds  below 9 knots were
ignored and higher speeds were plotted on a square-law scale. The prin-
cipal wind directions  are  Indicated  on the Figures.  These show good
agreement among the stations in the timing  of  the  wind disturbances,
but speeds  appear  to be considerably higher at station 18 than at the
land stations.  It should be  pointed  out,  however, that the 2-hourly
envelopes at station 18 include, by definition, extreme values, whereas
hourly readings at the land stations will not normally  include extreme
values.  The square-law presentation considerably exaggerates this dif-
ference. Nevertheless, there seems little doubt that speeds were higher
over the water than over land.

       Detailed comparison between  wind at station  18 and current and
temperature fluctuations at stations 15, 17, and 20 were compiled (Fig-
ures 10-7 through 10-14) for 15-day intervals within the period July 16
through August 30, 1963.  The Figures display  the following variables:
temperature at two depths for stations 15 and 17 and at four depths for
station 20; and, for all stations,  2-hour envelopes  of current direc-
tion and  speed  at  one  depth.  These take the form of vertical lines
Joining the extreme high and low values and covering the range of vari-
ation in current direction for each 2-hour period.   Current directions
are those toward which the current is flowing (and this also applies to
Figure 10-15) and wind directions are those from which the wind is com-
ing.  The Figures, which present a lot  of  information  in  compressed
form, show many significant correlations and points of interest, only a
few of which can be touched upon here.

       Station positions are listed  in  Table  10-1.  Of the Project's
two stations near the railroad  ferry track, one, station 17> was close
inshore and the other, station 20,  although  not in mldlake,  was more
representative of open lake conditions. The same can be said of station
15, some 4-9 km south of the track.

       As expected from its location 4 km from a N-S shore,  station 17
frequently alternates between southerly and northerly currents, strongly
dependent on wind direction and showing a fairly rapid response to wind
changes, for instance August 22-26 (Figure 10-11). However, in spite of
shore proximity,  there  were quite  long  intervals of rotary currents
                                  334

-------
                               TABLE 10-1

                         POSITIONS OF STATIONS
             LATITUDE   LONGITUDE
 STATION       °N          °W
              DISTANCE (KM)
              FROM W SHORE
                  DISTANCE (KM) FROM
                  MILWAUKEE-MLJSKEGON
                  RAILROAD FERRY TRACK
   17
   18        ^3008'
(wind records
   only)
(MV Cisco
anchor station)
   20

   15
87°51'

87°25'



8T°08'
86°32'

86°36'
    4

   39



   63



FROM E SHORE

   18

   31
12 N

 7 N



12 N
 6 S

49 S
                                    335

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-------
                                             -  LAKE  MICHIGAN
                       WIND  AT STATION  18
                                        IN  CENTIMETERS/SECOND
TEMPERATURE AND CURRENT
AT STATION   20
CURRENTS  AT 60  m  DEPTH
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                                                   RIVER  BASINS  PROJECT
WIND AT STATION  18  COMPARED  TO
TEMPERATURE 8 CURRENTS - STA. 20
    US DEPARTMENT OF THF
FEDERAL WATER POLLUTION CONTROL  AOMIN
Great Lak«s Region           ^hicu^i  .nt.i
                                 342
                               10-13

-------
                       WIND  AT  STATION  18  -  LAKE  MICHIGAN
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   16    17    18
                   19
20    21   22    23
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24   23    26    27    28   29   30
TEMPERATURE AND CURRENT

AT STATION   20

CURRENTS  AT 60 m  DEPTH

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                                                   RIVER  BASINS  PROJECT
                     WIND  AT STATION |8 COMPARED  TO
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                                                                            10-14

-------

• W

w W W W
	 ED 	
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2
E E E E
	 £V—
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                                                      1/2 CYCLE
                                                            •20—|
                                                      •Xs
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SECTIONS, AT QUARTER CYCLE  PHASE INTERVALS
ACROSS A  UN) NODAL  AI^D  TRINODAL  STAND-
ING  POINCARE'  WAVE IN A  TWO-LAYERED
LAKE,  ROTATING  COUNTERCLOCKWISE,
REPRESENTING  A  SECTION  ACROSS CENTRAL
LAKE  MICHIGAN  LOOKING  NORTH.

(Mortimer.unpublished, April, 1967)
     GREAT  LAKES — ILLINOIS
      RIVER  BASINS  PROJECT
  SECTIONS ACROSS a UNINODAL
     and a TRINODAL WAVE
    U S DEPARTMENT OF THF INTERIOR
FEDERAL WATER POLLUTION CONTROL AUMIN
Great Lakes Region           Chicugo I'.IPC.S
                                                                   FIGURE 10-15

-------
associated with internal waves  (August U-9,  Figure 10-10),  or indica-
tions of rythmic fluctuation in direction, or the combination of a uni-
directional current with rotation  (Figure 10-9,  July 28-31  and Figure
10-10, August i)--9).

       Compared with station 17,  the  open  Lake  stations (15 and 20)
were dominated by  rotary  currents for a much greater part of the time
and with a more circular current vector  envelope  (station  20  during
early August, Figure 10-13); but there were also occasions, particularly
after strong winds, when more or less steady currents prevailed (station
15, Figure 10-7, August lk-15; and station 20, Figure 10-lU, August 21-
2^). In general, the role of the wind in changing thermocline depth and
in setting currents and internal waves in motion is evident in the Fig-
ures; and these also give information on  the  relative  timing  of the
responses.   It is also apparent that, particularly during intervals of
more or less steady flow, the current speeds and the range of speeds at
station 15 were much greater than at the other stations.

       Another  important result which the Figures demonstrate is that,
with rare exceptions (station 17, Figure 10-10, August U-5) temperature
fluctuations at any one station, resulting from internal waves, were in
phase at all depths (station 15, Figure 10-8, August 18-22; and station
20, Figure 10-13,  early August, but see earlier remarks concerning the
15-m trace).  From in-phase  behavior  of this  kind it can be inferred
that the internal waves are those of the first vertical mode, appropri-
ate to a  two-layered  system, in which the flow is in one direction in
the upper layer and in the opposite direction in the lower layer.  This
was the current  distribution  found at the M. V. Cisco anchor station.
As mentioned in Chapter 6, there is evidence that the  current reversal
across the thermocline is not  characterized  by a layer of  zero flow,
but that  there is a progressive rotation of the current vector, total-
ing 180°, on passing downward through  the thermocline.  A clear demon-
stration  of  this  state  of  affairs  is not provided by  the Figures
presented here (although there were clear  examples at other  stations)
because, with the exception of  station 17 on July 2k,  and during  the
latter half of August,  the current measuring depths were usually below
the thermocline.  Perhaps the current behavior during the interval July
214-28 at station 17  when the thermocline moved upward through the cur-
rent measuring depth (15 m),  might  be  interpreted as a "change-over"
of this kind  between a southerly current above and a northerly current
below the thermocline.

       Of particular interest is the  opportunity,  provided by Figures
10-7 through  10-14, of testing conformity with theoretical predictions
derived from the standing Poincare wave model. A particular period, the
interval August k-7 was selected when the records from stations 17, 20,
and 15 showed  internal  wave  activity coupled with rotating currents,
and which  included  part of a  M. W. Cisco anchor station series at Mg
in midlake.


                                   3*5

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       To assist the interpretation,  Figure 10-15 presents, in simpli-
fied form,  cross-sectional  pictures of thermocllne  displacement from
the equilibrium level, and current distribution in the lover layer, for
a transverse uninodal and transverse trinodal Internal standing Poincare
wave in a two-layered lake, rotating counterclockwise.  It represents a
section across Lake Michigan looking north, "but for simplicity, internal
Kelvin vaves  or other  mechanisms generating inshore currents parallel
to the shores have teen omitted.   The theoretical current distribution
in the upper layer will be everywhere 180° out of phase with that indi-
cated for the lower layer, and  the  current  speeds  in the two layers
will be inversely proportional to the relative layer thicknesses.  Only
internal waves of the first vertical mode, i.e.,  appropriate to a two-
layered system, are considered.  The illustrations,  for each nodality,
represent one complete cycle of the oscillation at quarter-cycle stages.
Letters display the direction toward which the  current is  flowing and
the size of the letter  indicates  current  speed.  Dots represent zero
current  at the anti-nodes, on the assumption that the section bisects a
standing Poincare wave cell, i.e., passes through the points of maximum
elevation and depression of the thermocline.  At other sections through
the cell the general  current  distribution  is similar,  but there are
small currents at the shores and at other antinodes, if other antinodes
are present  (M. A. Johnson, personal communication).  The nodes are at
the points marked X,  and the relative positions of stations 17, Mg and
20 are indicated.

       By inspection of the  trinodal  case,  and  dividing the section
into adjacent  compartments  bounded by  each antlnode  and its nearest
node, a correlation table can be constructed (Table 10-2, with nodes at
X and antinodes at Y),  and  extended  to  derive  the  pattern for any
nodality, along the following lines:   the  uninodal  pattern comprises
compartments 1 and 2;  the binodal pattern comprises compartments 1, 2,
3, and 4; the trinodal pattern is provided by the compartment series 1,
2, 3, 4,  1, 2; the quadrinodal pattern  by 1, 2, 3, k, 1, 2, 3, k; the
quintinodal by 1, 2, 3, k, 1, 2, 3, 4, 1, 2; and so on. In other words,
correlations  between  thermocline  elevation  and  current  directions
between a pair of  stations can only indicate which nodality is present
if the information is combined with knowledge of the geographical posi-
tions of the stations and of  the observed  or presumed position of the
nodes.  It also appears likely  that, at least  as far as  the currents
are concerned,  the higher the nodality, the more quickly the wave will
die down, leaving the lower nodalities to dominate the scene. A further
guideline for Lake Michigan—in  which the normal effect of a wind dis-
turbance is to force  the thermocline to tilt downward on one shore and
upward on the other—is that odd-numbered transverse nodalities will be
the rule.

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       Table 10-3 summarises, for stations 17, >fe,  20,  and 15, during
the relatively simple episode,  August U-7,  1963,  the temperature and
current information  needed  to make the  comparison between theory and
events  in  the  Lake.  The stations 17 and Ife form a pair in which the
thermocline elevations and lover-layer currents  were  approximately in
phase; and the  same  is  true  of the station pair 20 and 15-  The two
pairs, however, are approximately 180° (i.e., close to 8£ hours or one-
half period) out of phase with each other.   This  result, coupled with
the  geographical  location  of  these  stations,  is consistent with a
Poincare" wave of transverse nodality one  (compare  Figure  10-15 upper
part) on the assumption that the uninode  lies to  the east  of Mg (and
that there  is no longitudinal node between 20 and 15).  The next para-
graph provides evidence of  a uninode  to the  east of Mg.  If the uni-
nodal  picture  is therefore accepted, the  phase relationships between
thermocline  elevation and current  direction at  all stations serve to
confirm the standing Poincare" wave model, an Important result.  It will
also be noted  that a fit with the  trinodal case  (Figure 10-15, lower
part) would be impossible.  While—as pointed out in earlier discussion
concerning Table 10-2—a fit with some  higher  nodality  than three is
conceivable  in  theory,  this would be a most unlikely interpretation,
which  in any case appears  ruled out by  consideration of wave period,
not discussed here.

       During the interval  August 4-7, six temperature  cross sections
were completed using  railroad car ferries.   When  the 10°C isotherms,
which  represent  thermocline depth, are plotted on a common depth/time
scale, there is evidence of a node  at  76 km from  Milwaukee, at which
point the depth range of  the  thermocline  did not exceed 2 m over the
whole  interval.  On this occasion, however, the presumed node was less
clearly defined than the 66-km node in Figure 10-2, perhaps because the
wave amplitudes were then larger, following the storm on August 16-17—
and it was also in a different position.

       As mentioned earlier, Figure  10-2  for  August 19-22 suggests a
combined response to a  transverse uninodal  and trinodal Poincare' wave
in which the midlake nodes of  each  system were coincident at approxi-
mately 66 km from Milwaukee.  While the temperature records at stations
20 and 15 at that time showed  clear  indications of internal  waves of
near-inertial period, set in motion by the storm  on August  16-17, the
current pattern was too confused to attempt the correlations similar to
those carried  out  above for the  August 4-7 episode.  It appears that
strong unidirectional currents, set in  motion by the storm, masked the
rotational components.  All that can be said with certainty is that the
thermocline  elevations at stations  20 and 15 were,  on this occasion,
out of phase, suggesting  that there may have been a  longitudinal  (or
transverse) Poincare node between them.  The  temperature  recorders at
station 17 were in the upper layer and a long way from the thermocline;
                                   3^7

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                               TABLE 10*2

    CORRELATION TABLE FOR STANDING POINCARE WAVES OF VARIOUS TRANSVERSE
  NODALITIES IN A RECTANGULAR WO-LAYJBR1D BASIN ROTATING COUNTERCLOCKWISE
                   (COMPARE FIGURE 10-15, TRINODAL CASE)
nodes at:
Compartment No. *
Maximum "thermocline" elevation (+)
or depression (-)
Current direction in lower
layer, corresponding to the
above maximum elevations or
depressions .
trinodal case
S^
( )
V binodal case /
vuninodal case /
^ X ' X X
il 1
2 3 1 k 5 J, 6
» N S S N B
                                left hand
                                (W) shore
                                  t
1
I
antinodes at:
right hand (E)
shore for tri-
nodal case
        t
        y
*See text for definition.

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                               TABLE 10-3

  CORRELATION BETWEEN TEMPERATURE  'WAVES' AND CURRENTS AT STATIONS
    17, Jfe AND 20 ON OR NEAR THE MILWAUKEE-MUSKEGON SECTION (AND
    AT STATION 15), AUGUST 4-7, 1963.  FOR STATION POSITIONS SEE
       TABLE 10-1.  DATA OBTAINED FROM MORTIMER'S UNPUBLISHED
     OBSERVATIONS AT Mp AND ON RAILROAD FERRY SECTIONS, AND BY
         INSPECTIONS OF FIGURES 10-10, 10-13, AND 10-7.
Station
Approximate mean thermocllne depth
(inspection of ferry transects) — m
Depth of temperature record shoving
greatest amplitude -- m
Current measured at — m (all below
thermocline at this time)
Approximate hour (C.S.T. ) of occurrence
of temperature "troughs," assumed
equivalent to internal wave "crests": I"
4th <
>
Aug. 5th <
I
f
*observed "crests" at Hp 6th <
L
f
7th {
I
Approximate direction toward which
the current was traveling in the
lower layer at the above times.
Approximate mean current speed,
cm/sec .
17

10

10

15


7

2k

17

10

3

20

NNE

5

M2«* 20

18 15-20

15

various 60


6*
15
23*
8

1

18

11


NNW SSE

10-15 10

15

17

15

22







23

16

9


SSE

15

**M.V. Cisco anchor station.
                                    349

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internal wave indications are  therefore  unreliable,  but such as they
are they  suggest  that station 17 »ay hare been out of phase with sta-
tion 20.  These indications are not conclusive but are not, as far they
go, inconsistent  with the dominance of a transverse  trinodal standing
wave pattern on that occasion.
                                  350

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                              CHAPTER 11

                   RELATIONSHIP TO WATER USE AREAS
Introduction

       Although not all of the initial purposes  of this study of water
movements in Lake  Michigan  were  accomplished, the information gained
will contribute greatly to the development of more effective water pol-
lution control programs for the Great Lakes.  For example, planners can
now determine  the outer  limits of diffusion rates in the Lake and the
net flow along the shore in the vicinity of an outfall, stream, or water
intake.

       The wise utilization of  the  Lake, on a sound technical founda-
tion, has become a reality.  The  preservation  of  an acceptable water
quality for the  future will depend on the course man takes in the dis-
posal of his wastes.

       Physical factors affecting water use areas include a broad range
of forces which interact to produce a complicated relationship.  Fortu-
nately one or two of the factors are usually most dominant and can des-
cribe the events which occur.  Motions in the Lake can be characterized
as  either horizontal or vertical.  Vertical motions were inferred from
thermal gradients.  Although vertical currents are very small, the max-
imum being in  the  range  of  0.06 cm/sec,  the distance  scale in the
vertical is very small when compared to the horizontal scale.  Vertical
currents may be an order of magnitude greater in the winter than in the
summer.  Hutchinson (44) shows  several  instances  of summer  vertical
currents of an  order  of  magnitude  greater  than those found in Lake
Michigan. The currents found in Lake Michigan are primarily a result of
displacement of the isotherms due  to  internal  wave motion and conse-
quently result  in very little mixing.  Horizontal and vertical motions
are produced by external,  internal,  and  secondary  forces.  External
forces include:  wind, atmospheric  pressure,  and lunar or solar tide-
producing forces.   Internal  forces  can  properly be  labeled density
gradients.  These include  changes in mass distribution  in  heat or in
dissolved solids.  Secondary  forces  include Coriolis force, friction,
turbulence, and centrifugal force.   Secondary  forces  do  not produce
currents but affect the currents that are produced by other means.

       The above forces, whether  producing  massive turbulence, gentle
streamline  flow, thermal bars, or thermocllnes,influence water uses of
the Lake.  They can rapidly  disperse  highly  concentrated wastes of a
hazardous nature or they can transport them with little mixing to crit-
ical water use areas.
                                  351

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       The studies reported herein describe conditions under which pol-
lutants will  be moved  from point to point and permit determination of
probable concentrations and effects on water use areas. From this know-
ledge appropriate pollution abatement measures can be devised to protect
and enhance the quality of the Lake waters for all legitimate uses.

       Pollutants are discharged or put into Lake Michigan through many
sources such as:  sewage outfalls,  industrial waste discharges, vessel
discharges, dumping of dredged material, and storm overflow sewers.  In
addition,  storm-generated waves will resuspend detritus and other pol-
lutants and produce a recycling of  these  materials.  These discharges
are the principal sources  of waterborne  wastes which  will affect the
users of Lake Michigan water. Although some of the waste sources listed
may contribute minimal amounts of pollution,  the  very  long retention
period or flowthrough time requires a careful look at a.n waste sources
and the development of  a water pollution control  program which places
appropriate emphasis on future conditions.

Water Use Areas Along Shore

       Beach and water intakes along or near the shore will be affected
by nearby sources of pollution;  proper  location  and  design of waste
outlets  can  minimize such effects.  Bottom materials are usually sand
in a beach area  and normally swept free of settling debris that may be
recycled.  Likewise, vessel  discharges  and  the  dumping  of  dredged
materials  will  normally  occur 3 °r more km from most beaches.  Storm
overflow sewers,  sewage outfalls, and industrial waste discharges pre-
sent the greatest hazards to public bathing.

       The steady  discharge  of  pollutants,  as  a  sewage outfall or
industrial  waste discharge, cannot be  compared directly to the  occa-
sional once a month, k- or 5-hour discharge  of a storm  sewer overflow
or the washing of oil tanks once a year. These can be called nonsteady-
state and represent pools of  pollution.   Such problems  must  receive
special consideration.

       Based on studies of drogues,  the maximum  and minimum diffusion
factors were calculated for  moderately calm conditions, and not criti-
cal or minimum diffusion rates. However, if a discharge were part of an
oil residue or other oil-based pollutant, little or no dispersion would
occur  because of the lack of mixing.  Therefore, all references to the
dispersion or  mixing  of  discharges refer to wastes which are soluble
or mix readily with Lake water.

       At 150 m (500 feet) from the source, under minimum mixing condi-
tions (calm periods), a pollutant will be at or near 100 percent of its
original concentration.  At 750 m (2,500 feet) the pollutant will be 20
                                  352

-------
percent of its original concentration,  and at 1,500 m   (5,000 feet) it
will  be at 10 percent.  Similar  values are found for pools or  "slugs"
of pollutants.

       The greater the diffusivity, UJ1, the more a pollutant moves out-
ward and upstream.  It can be easily seen from  the  above  percentages
why contaminants, such  as taste- and odor-producing  hydrocarbons, can
travel 15,000 m (50,000 feet)  and still be 1 percent of their original
concentration, and thus cause problems.

       Vessel discharges into restricted harbors, such as boat marinas,
constitute  a potential  hazard because  of the number of vessels which
congregate in a small area.  Since most harbors  are restricted  in area
and depth, and have a small entrance,  physical factors  do not  play a
large role in  dilution or dispersion.  Currents or other water  motions
are nearly nonexistent and stagnant water conditions may prevail. Unless
reasonable care is  taken to limit  the discharge of  pollutants these
harbors can become severely  degraded in a few years.  Milwaukee Harbor
is an example of such conditions.

       Thermal barrier conditions during the fall,  winter,  and spring
period  limit the  outward extent of the effective mixing volume.  This
factor appears  to be  responsible for  unusual solids   build-up in the
nearshore waters during  this period.  The late spring storms and  lake
overturn break up the zonation due to the thermal bar and create condi-
tions for effective mixing with the Lake proper.   However,  during the
summer when the thermal bar no longer exists, a similar  build-up occurs.
Boundary effects, friction, and the southern gyre are probably   respon-
sible for the lateral transfer of water along the shore.  Upwelling and
downwelling in summer are positive  signs that this restriction  is much
weaker than during the winter period.

Water Use Areas in the Lake

       Water supply intakes, fish and aquatic  life,  and  recreational
boating are some of the more important uses of lake water away from the
shoreline.   Outfalls or water intakes are fixed positions, rarely more
than 6.k km (k miles)  from shore.  The dumping of dredged materials is
normally confined to fixed  geographical areas and is usually more than
1.6 km (l mile) from any water intakes. Vessel discharges in such areas
are restricted but much is still left to the discretion  of the   Captain
of the ship.

       Normally wastes discharged into the Lake have more mixing than a
shore-discharged effluent. This arises from the fact that the pollutant
can rise through a column of lake water (if the pollutants are lighter)
and is continually mixed. If the currents are nearly stationary, then a
mass or pool of pollutants can build up and create a potential problem.
                                  353

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       Steady currents, of any magnitude, will assist in the dispersion
of pollutants discharged into the Lake. However, during summer periods,
the thermocline  acts as  a barrier against mixing, and  all  effluents
discharged above the thermocline  will  normally  not be dispersed into
the lower levels unless density is an additional factor.

       The sum total of the effects of physical  factors indicates that
if the quality of lake waters is to be  maintained  for »il  legitimate
uses,  indiscriminate discharges of wastes must be eliminated or placed
under strict control.

Significant Factors

       There are several physical factors which contribute significantly
to the dispersion (or lack of dispersion) of pollutants.  The processes
not previously identified in Lake Michigan  and  determined  by Project
studies are:

       1.  Diffusion coefficients. The maximum value found was wi = O.k
and minimum ""i = 0.2.  In an area of convergence  the minimum may be as
low as ^i = 0.08. These values represent the outer limits of diffusion.

       2.  Inshore zonation of  suspended  materials.   Materials  dis-
charged into the inshore zone, 0 to 6 km, will  normally tend to remain
in the zone.  During the late fall  and early  spring a thermal barrier
condition restricts the normal diffusion between  inshore  and offshore
waters.  The thermal  gradients are assisted  by  the  fact that as one
approaches  the  shore  the water movements  tend to parallel the shore
rather than move in any direction  under the wind influence.  In summer
this conformality of flow, due to boundary conditions,  is  enhanced by
the tilting of the thermocline and  the  existence of the southern gyre
creating other artificial boundaries.

       3.  Lake Michigan has a winter  thermocline at the 120- to 180-m
level which restricts  turnover in  the deep central basin.  Although a
lake turnover does not appear to occur in  this basin every year, it no
doubt occurs at least once every 10 years.   The  southern  basin mixes
from top to bottom every year.

       k.  No permanent type of circulation pattern exists in the Lake,
but four general circulation patterns exist, depending on wind regimes.
Ice conditions on  the  Lake  are  sporadic  and are rarely 100 percent
(perhaps once in 30 years). A complete ice cover preventing random wind
action permits the formation of true inertia currents which rotate with
a period of a half  pendulum  day.  In the summer the internal wave, in
the main  portion  of the Lake, prevents the wind from directly affect-
ing the rotary circulation patterns.  A small cellular structure occurs

-------
on the broad circulation patterns  and  produces  a complex interaction
between wind and water movement.

       5.  The summer internal  wave on the  thermocline begins in late
spring and exists until early December.  The direction  of  flow in the
epilimnion is generally 180° out of phase with the water in the thermo-
cline and below. The horizontal rotation of the water due to the inter-
nal wave exists from top to bottom  in the Lake.  The motion due to the
internal wave is independent of  the net circulation  pattern which may
exist.

       6.  Wind energy from storms  is  transmitted  through the entire
column of water,  both in  summer and winter.  No thermal barrier, such
as a thermocline, exists to  inhibit  energy  transfer  in the winter—
except  for  the  reverse  thermocline in the deep hole of the northern
basin.  In the summer the direct input of energy from a  storm  excites
the internal wave pattern and produces  extremely large waves  (over 10
meters) and accomplishes some mixing at the thermocline interface.  The
formation of the large waves in turn appears to transmit into the lowest
layers,  increasing the speed within the rotating currents proportional
to the input.  The decay of the energy input is related to friction.
                                  355

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                           ACKNOWLEDGMENTS
       To thank all the people who have contributed to this study would
virtually call for a  whole new  chapter.  To  those  who have assisted
directly, the GLIRB Project  staff will be always grateful.  Noteworthy
among  these  are:  Drs. C. H. Mortimer and A. M. Beeton, University of
Wisconsin-Milwaukee;  Drs. V. E. Noble, J. C. Ayers, D. C. Chandler and
F. Bellaire, University of Michigan;  Dr.  E.  Birchfield, Northwestern
University; Dr. G. Platzman, University of Chicago; Drs. B. Kinsman and
A. Okubo, Johns Hopkins  University;  Dr.  K. Rodgers,  University   of
Toronto; Dr. R. A. Ragotzkie,  University of Wisconsin; Dr. F. Webster,
Woods Hole Oceanographic Institution;  Dr.  H.  Stommel,  Massachusetts
Institute of Technology; Dr.  W. J. Pierson, E. Mehr and F. Malone, New
York University; Dr. R. Gaul,  Texas A & M; Dr. D. L. Harris, ESSA; and
Mr. T. L. Richards, Department of Meteorology, Canada.
                                   356

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                                    357

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                                   358

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                                  ZSk

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