EPA-650/4-74-007

April 1974
Environmental  Monitoring Series



                                                       \

                                                        UJ
                                                        O
                                   '^^^^^^^^i^M^^^^^^^

-------
                                  EPA-650/4-74-007
           DETERMINATION
 OF  ENERGETIC  CHARACTERISTICS
   OF  URBAN-RURAL  SURFACES
IN  THE  GREATER ST.  LOUIS  AREA
                    by

           W. F. Dabberdt and P. A. Davis

            Stanford Research Institute
            Menlo Park, California 94025
             Contract No. 68-02-1015
              Project No. 26AAI/J6
            Program Element No. 1AA003
         EPA Project Officer: James L. McElroy

              Meteorology Laboratory
         National Environmental Research Center
       Research Triangle Park, North Carolina 27711
                 Prepared for

        OFFICE OF RESEARCH AND DEVELOPMENT
       U.S. ENVIRONMENTAL PROTECTION AGENCY
             WASHINGTON, D.C.  20460

                  April 1974

-------
This report has been reviewed by the Environmental Protection Agency
and approved for publication.  Approval does not signify that the
contents necessarily reflect the views and policies of the Agency,
nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.
                                  11

-------
                               ABSTRACT




     The role of surface geophysical characteristics (e.g., albedo,


thermal admittance, Bowen ratio, emissivity) in the partitioning of


energy at the complex and heterogeneous metropolitan earth-air interface


has been evaluated through a unique application of Lettau's climatonomy


theory.  In contrast to the conventional approach that first specifies


an inventory of "appropriate" surface descriptors and then attempts to


evaluate or interpret observed climatic features, the climatonomical


methodology permits the determination of the surface descriptors on the


basis of the observed diurnal response of the surface to the observed


forcing function of available solar energy.  Features of various land-


use types (e.g., farmland, suburban residential, commercial) can then be


evaluated in the context of the surface energy budget.  For example, if


the subsurface heat flux is treated by assuming the medium is a homogeneous


conductor, then an effective thermal admittance is derived that satisfies


the assumption and the observed diurnal response of surface temperature.



     During three designated experimental periods, totalling some 50


hours, that began with clear skies and reasonably steady meteorological


conditions, aircraft data-collection missions were flown repetitively at
                                                        *
2-3 hour intervals from altitudes of 460 m and 1220 m mgl along a selected


flight track across the St. Louis area.  Aircraft data included temporal


and spatial measurements of downwelling and upwelling solar radiation,


the effective surface radiative temperature, and the air temperature.


Continuous records of downwelling solar and atmospheric irradiances were


obtained at a single surface station located adjacent to the flight track.
 *
 Above mean ground  level.
                                  iii

-------
     The feasibility of implementing the climatonomical approach was



evaluated on the basis of experimental data obtained on 9 August 1972;



abrupt weather changes occurred during the other two periods and limited



their suitability for extensive analysis.  Albedos over the various land-



use types showed a maximum near 16 percent over the rural sites comprising



farms, fields, and woods with a minimum near 13 percent over the older



urban residential and commercial/industrial sites.  Urban surface



temperatures were higher than the rural surface temperatures with the



maximum difference (10-15 degrees C) occurring in the early afternoon.



Aircraft albedo and surface temperature measurements, the surface



irradiance measurements, and two balloon soundings of the lower atmosphere



were used in the climatonomical analysis to determine both thermal



addmittance and the inverse Bowen ratio for each of nine land-use sites.


                                                            —1/2  —1
The thermal admittance ranged, from a minimum near 20 mly sec    °C



for urban and suburban sites to about 85 for the wooded sections.  The



inverse Bowen ratio ranged from 0.22 in the urban area to 2.9 for farmland.




     On the basis of the results, the method is judged feasible and



attractive for exploring additional factors, such as the effect of natural



surface alterations (e.g., wetness and ground cover) on the surface



energy budget.  The method has significant potential as a tool  for applied



studies of climatic effects and modifications relating to land-use planning,
                                    iv

-------
                                CONTENTS


ABSTRACT	

LIST OF ILLUSTRATIONS	     vii

LIST OF TABLES	      xi

FOREWORD	     xiii

  I  INTRODUCTION 	        1

     A.   Objectives	        1

     B.   Scope	        3

 II  EXPERIMENTAL PROCEDURES   	        5

     A.   Surface Observations  	        5

     B.   Aircraft Observations	        6

     C.   Data Processing	       13

          1.    Solar radiation	       13
          2.    Surface temperature  I	       15

III  METEOROLOGICAL CONDITIONS  	       19

     A.   9 August 1972	       19

     B.   11  August 1972	       21

     C.   23  April 1973	       22

 IV  AIRCRAFT OBSERVATIONS   	       25

     A.   Solar Data	       25

     B.   Surface Temperatures	       32

     C.   Air Temperatures	       37

  V  CLIMATONOMICAL ANALYSIS   	       41

     A.   Climatonomy Theory   	       41

     B.    Method of Approach	        47

-------
   V    CLIMATONOMICAL ANALYSIS  (continued)




        C.    Application and Results	        61





  VI    CONCLUSIONS  AND RECOMMENDATIONS	        75





 APPENDIX





        A    AIRCRAFT DATA SUMMARY 	      A-l





REFERENCES	      R-l
                                     VI

-------
                              ILLUSTRATIONS
11   Aero Commander Aircraft of Colorado State University
     a)  Aero Commander 500 B (left)  alongside a Cessna
         182 Skylane (right)
     b)  Interior View of Equipment Rack in Aero Commander  ....      8

2    Flight Tracks, Check Points,  and Locations Selected
     for Harmonic Analysis of Data	      10

3    Variations in Response between Wide-Angle and Narrow-
     Angle Solarimeter Measurements of Surface Reflectance
     and between 4-Degree and 20-Degree Radiometric Measure-
     ments of Surface Temperature  	      14

4    Total Solar and Atmospheric Radiation Incident on
     Horizontal Surface, Granite City, Illinois,
     9 August, 1972	      20

5    Total Solar and Atmospheric Radiation Incident on
     Horizontal Surface, Granite City, Illinois,
     11 August, 1972	      23

6    Aircraft Solar Measurements,  1400 CDT Flight,
     9 August, 1972	      26

7    Height Variations of Measured Incident Solar Radiation,
     11 August 1972	      29

8    Normalized Aircraft Solar Measurements, 1700 CST Flight,
     23 April 1973	      31

9    Aircraft Radiometric Surface  Temperature Measurements,
     1400 CDT Flight,  9 August 1972	      33

10   Normalized Aircraft Radiometric Surface Temperature
     Measurements, 1700 CST Flight, 23 April 1973	      34

11   Urban and Rural Surface Temperature Variations with Time
     (a)  9 August 1972
     (b)  23 April 1973	      36

                                   vii

-------
                        ILLUSTRATIONS (Continued)
12   Aircraft Air Temperature Measurements,  1400 CDT Flight,
     9 August 1972	    38

13   Site R-l	    50

14   Site R-2	    50

15   Site R-3	    50

16   Site R-4	    50

17   Site R-5	    51

18   Site R-6	    51

19   Site R-7	    51

20   Site R-8	    51

21   Site R-9	    52

22   Near-Surface Meteorological Stations Operated by Illinois
     State Water Survey, August 1972	    57

23   Comparison of Two-Harmonic Temperature Wave at Station 022
     and Two-Harmonic Regression Analysis for Site R-l Using
     Data Points	    60

24   Effective Surface Radiative Temperature from Two Aircraft
     Altitudes at Nine Sites on 9 August 1972	    62

25   Diurnal Variation of  Derived Departures (from daily average)
     of Atmospheric,  Latent, and Subsurface Heat Flux Densities
     for Three Land-Use Types:  Farmland, Commercial/Industrial,
     and Suburban Residential  	    74
                                 viii

-------
                           ILLUSTRATIONS (Concluded)
 A-l   Aircraft Solar Measurements,  0930 CDT Flight,
       9 August 1972	    A-6

 A-2   Aircraft Solar Measurements,  1145 CDT Flight,
       9 August 1972	    A-7

 A-3   Aircraft Solar Measurements,  1400 CDT Flight,
       9 August 1972	    A-8

 A-4   Aircraft Solar Measurements,  1630  CDT Flight,
       9 August 1972	    A-9

 A-5   Aircraft Solar Measurements,  1915  CDT Flight,
       9 August 1972	    A-10

 A-6   Aircraft Solar Measurements,  0900  CDT Flight,
       11 August 1972	    A-ll

 A-7   Aircraft Solar Measurements,  1130  CDT Flight,
       11 August 1972	    A-12

 A-8   Aircraft Solar Measurements,  1400  CDT Flight,
       11 August 1972	    A-13

 A-9   Aircraft Solar Measurements,  1630  CDT Flight,
       11 August 1972	    A-14

A-10   Aircraft Radiometric Surface  Temperature Measurements,
       9 August 1972	    A-15

A-ll   Aircraft Air Temperature Measurements,  9 August  1972  	    A-17

A-12   Aircraft Radiometric Surface  Temperature Measurements,
       11 August 1972	    A-19

A-13   Aircraft Air Temperature Measurements,  11 August 1972   ....    A-21

A-14   Aircraft Radiometric Surface  Temperature Measurements,
       23 April 1973	    A-23

                                    ix

-------
                               TABLES
1    Chronological  Summary  of Aircraft Operations in
     St.  Louis	     11

2    Description of Surface Areas Selected for Analysis 	     53

3    Results of Harmonic Analysis of 9 August 1972 Surface
     Observations of Downwelling Short- and Long-Wave
     Radiation at Granite City, Illinois  	     54

4    Comparison of  the  24-Point Harmonic and 8-Point Regression
     Analyses of the Near-Surface Ambient Temperature on 9 August
     1972 in the Greater St. Louis Area	     58

5    Albedo Values  for  the  Nine Surface Areas as Measured on
     9 August 1972  from the Two Aircraft Altitudes	     66

6    Climatonomic Parameters for 9 August 1972, in the Greater
     St.  Louis Area	     67

7    Derived Amplitude  Terms for Atmospheric Sensible, Latent,
     and  Subsurface Heat Flux Densities	     73
                                  xi

-------
                               FOREWORD









     A large number of people contributed a variety of skills  and



services to this program:  Contract Manager for the study was  Dr.  James




L. McElroy, Meteorology Laboratory, National Environmental Research




Center, EPA, Research Triangle Park, N.C.;  Ms.  Patricia Buder, Research




Meteorologist, and Mr. Hisao Shigeishi,  Mathematician, SRI,  contributed




significantly in the analysis and processing of the data; Dr.  Edward



Uthe, Atmospheric Physicist, SRI, provided  the  surface radiation data




during August 1972; Dr. William Marlatt,  Mr.  Don Hill, and Mr. Duane



Adams, Colorado State University, provided  the  aircraft and  instrumen-




tation services under subcontract to SRI; Mr. Stan Changnon, Illinois




State Water Survey, provided near-surface temperature records  for




August 1972; the National Weather Service,  Lambert Field, St.  Louis,




provided forecast information and EMSU soundings;  and Dr. Clifford




Murino, Vice President for Research, St.  Louis  University, kindly  assisted



by providing facilities at the University for maintaining and  operating




the surface radiation station during April  1973,  in cooperation  with



Professor Donald E. Martin, Director of  Meteorology,  and Mr. Louis J.



Hull, both of St. Louis University.
                                 xiii

-------
                            I  INTRODUCTION








A.   Objectives





     It is well recognized that the complex air-earth interface plays




an important role in the behavior of the atmospheric planetary boundary




layer and in the differences in the structure of the rural and urban



surface energy budgets.  Understanding these differences (and the sub-



sequent partitioning of the net radiation) is further complicated by the




local heterogeneity of individual surface types (i.e., land-use patterns)




and the attendant difficulties in parameterization of the interface




energy fluxes.   Conventional approaches toward solution of the problem




implicitly  consider the local areas to be homogeneous on the broader



scale, and then proceed to first specify the appropriate surface




geophysical descriptors (e.g., albedo, thermal admittance, roughness) and




subsequently compute the energy fluxes.  One of the major difficulties




in this approach is the a priori specification of surface descriptors.





     To overcome this obstacle, we have developed and tested a method




whereby these descriptors are determined through an examination of




variations of the surface energy budget as a function of land use, and



the subsequent  analysis of these variations in terms of the associated




differences in the geophysical features of the surface.   Included among



the surface characteristics are radiative (albedo,  emissivity),  thermal




(heat capacity,  conductivity), and structural (aerodynamic roughness,




height-area-orientation)  properties.  Radiative and thermal characteristics




are affected by surface wetness,  but the importance of evapotranspiration



makes it necessary to add surface "type" as a characteristic, particularly




to distinguish  such features as cropland,  meadows,  parks,  and the like.

-------
To be useful in modeling, the influence of the surface characteristics


on the surface energy budget must be identified, even before associated


feedback reactions with the boundary layer can be considered fully.


     The basic objective of this study was the examination of the


variations of the surface energy budget throughout the greater St.  Louis


metropolitan area  (ranging from rural farmlands to suburbia to the


urban core) so as to evaluate these variations in terms of associated


differences in the thermal, radiative and aerodynamic geophysical features


of the surface.  Toward this end, we have drawn heavily from the


climatonomy theory of H. and K. Lettau*1  (1971).  In climatonomy, temporal


climatic variations are described analytically as unique response functions


to a prescribed forcing function.  More specifically, climatonomy may be


summarized as the quantitative determination of mean values and temporal-


spatial variations of:  (1) temperature,  the primary response function,


and (2) energy fluxes, the secondary responses (e.g., atmospheric and


subsurface sensible heat exchange, net effective infrared emissions,


evaporation) at a planetary surface in response to the solar forcing


function (i.e., available incident solar radiation).


     A major purpose of this study was to examine the feasibility of


obtaining representative empirical data on the spatial and diurnal


variations in the effective geophysical surface characteristics of selected


heterogeneous areas with different surface types.  Variations in the


diurnal response of surface temperature are reflected in the secondary


responses and depict the influence of the surface on the establishment of


rural-urban differences in the surface energy budget.  This information


should provide a more meaningful classification of distinct surface types


in terms of climatic responses to incident radiation.
*
 References are listed at the end of this report.

-------
B.   Scope





     The experimental program focused on the acquistion of data on the




spatial and temporal (i.e., diurnal) distribution of surface temperature,




and solar and terrestrial radiation for a variety  of surface types.  The



data may be conveniently categorized according to source:




     •  Frequent aircraft observations





     •  Continuous surface observations





     •  Supplemental, conventional observations.





The aircraft observations consisted of flights at two-to-three hourly



intervals over a 90-km path centered over the St.  Louis urban core; to




obtain as much independent data as possible, the initial and return legs




of each flight were made at different altitudes.  The primary aircraft



data included both upwelling and downwelling solar irradiance and effective




surface radiative temperature.  Supplemental aircraft observations included




surface photography and ambient temperature.  Representative measurements



of the albedo (based on upwelling irradiance measurements) and surface




temperature (based on upwelling radiance measurements) are difficult to




acquire except from a moving platform aloft.  In fact, over a very non-



homogeneous surface the only effective means of observing surface temper-



ature is by radiometric techniques applied in a nearly transparent



spectral region.   At this stage of investigation no emphasis was given



to a study of direct influences of the atmospheric boundary layer itself



on the radiative processes.  Instead, site representative measurements



of total downwelling irradiance were made at one surface so as to



incorporate directly any atmospheric influence. The other principle data




requirement is the boundary layer wind profile; this was available twice-




daily from the nearby Environmental Meteorological Support Unit (EMSU)




station operated  by the National Weather Service (NWS) .

-------
     Surface geophysical features derived through the analysis of the




surface response to the radiative forcing function were limited to two



parameters:  thermal admittance and inverse Bowen ratio.  This limitation




is a result of the number and type of measured values; to derive additional




geophysical features would require additional measurements, such as the



latent or sensible heat fluxes.  Even so, certain simplifying assumptions



had to be made:  photosynthetic and anthropogenic fluxes of heat were not




treated explicitly in the theory; however, their actual impacts on the



observations are implicit in the data and thus are reflected in the




derived values.  On the other hand, the August data used in the analysis




have the advantage that contributions from both processes to the surface




energy balance are most likely minimal.

-------
                      II EXPERIMENTAL PROCEDURES








A.    Surface Observations





      Although it would be desirable to obtain measures of the downwelling



irradiance at the surface simultaneously over each of the various urban



and rural surface types, it was necessary to accept a single site only.



However, for the clear conditions selected for study, a single location



should provide a representative measure of the forcing function at all



locations, except in situations with extreme variations in pollutant



loading.  An Eppley Precision Spectral Pyranometer (PSP) was mounted free



of sky obstructions to measure the total direct-plus-diffuse solar



irradiance on a horizontal surface.  During August 1972 this instrument



was installed at the Granite City Army Depot as part of an SRI METROMEX



experiment.2  At the same site the atmospheric radiation incident on



a horizontal surface was recorded from an Eppley Pyrgeometer Infrared



Radiometer (PIR).  Nearby observations of pressure, wind velocity,



temperature, and wet bulb temperature also were available; the SRI lidar



used during METROMEX provided a relative measure of local particle loading



of the lower atmosphere.  Data from other METROMEX experiments were



available for other locations in the St. Louis area.





      The surface site was established at St. Louis University during a



second field program at St. Louis in April 1973.  The same Eppley PSP was



used for the measurement of downwelling solar irradiance, but the



atmospheric radiation was inferred from concurrent measurements with a



C.S.I.R.O. Net Radiometer (NR).  The latter instrument was installed with



a blackened dome covering its bottom sensing surface.  This dome contains



a thermocouple junction; a reference thermocouple junction immersed in a



reference bath at a known temperature is used to determine the black




                                   5

-------
body radiation incident on the lower surface of the NR.  Thus,  the




residual difference between the black body radiation and the measured




net radiation gives the downwelling irradiance only.  At night, the



downwelling irradiance is simply the desired atmospheric radiation.




During the day, the separately measured total insolation (from the PSP




measurement) must be subtracted from the downwelling irradiance derived




from the NR to obtain the atmospheric radiation.  A nuisance with



operation of the NR was the requirement to supply nitrogen from a tank




to maintain dry-air pressure for inflation of the upper polyethelene dome




of the instrument.  Some difficulty was encountered in maintaining a




nearly constant pressure on the dome over an extended period of time




without readjustment.





      Data from the PSP and PIR during August 1972 and the PSP and NR




during April 1973 were recorded on a two-channel Hewlett-Packard Moseley




recorder.





B.    Aircraft Observations





      The two key measurements of the program were the diurnal variations




of surface temperature and of albedo over the heterogeneous lower boundary



of the urban-rural St. Louis area.  It was concluded that the only



feasible approach  to the acquisition of these data was the use of a light




aircraft for repeated low-level flights (throughout the 24-hour period)



along the same flight track, thus covering the  same surface features



each time.  The twin-engine Aerocommander aircraft (shown in Figure 1)




owned by Colorado State University (CSU) was selected.  This aircraft




had been used extensively for low-level meteorological experiments and



was equipped to acquire the type of measurements required in this study.





      A daily routine of nine flights was selected for documentation of



diurnal variations.  Each flight lasted approximately one hour, allowing




one-half hour for the departure leg and one-half hour  for the return leg






                                   6

-------
along the same track.  During August, take-off times originally were



selected for 0000, 0300, 0600, 0830, 1100, 1330, 1600, 1830, and 2100 in



Central Daylight Time.  Because of greater daytime variability in surface



properties flights were spaced more closely during  the day  than  during  the



night.  During April,  take-off times (Central Standard Time) were set



at 0100, 0400, 0630, 0900, 1130, 1400, 1630, 1900,  and 2200.  The flight



schedule was designed  to provide maximum data density during daylight



hours when surface temperatures change most rapidly.  This is particularly



important because the  analysis methodology required the specification



of the diurnal variation of the meteorological parameters in terms of a



Fourier expansion.





      Flight tracks were chosen to sample a variety of land-use types



and to approximately parallel the low-level wind flow; accordingly, they



were based in large part on the clear-sky wind rose climatological data



for the given times of year.  Two flight levels (departure and return)



were designated at 460 m and 1220 m above the mean ground level.  The



upper level, near the  top of the boundary layer and the cloud-base level



(for small cumulus clouds), provided an appropriate altutude for the



aerial photography.  In addition, by acquiring data at two levels, it



is possible, in principle, to infer the effects of atmospheric attenuation



on the measurements of surface temperature and albedo.





      Figure 2 illustrates the flight tracks adopted for August 1972



and April 1973.  These tracks were selected not only on the basis of



wind roses, but were designed to avoid the critical air space near



Lambert Field as well  as some of the higher obstructions in the



southwestern portion of the city.  Nevertheless, each track crossed an



interesting variety of land use patterns and visually identifiable



checkpoints.  River crossings are excellent checkpoints because they are



identifiable in both the surface albedo and temperature records.  River



crossings along the April track were superior to those in August because




                                   7

-------
  (a)  AERO COMMANDER 500 B (LEFT) ALONGSIDE A CESSNA
     182 SKYLANE (RIGHT)
(b)  INTERIOR VIEW OF EQUIPMENT RACK IN AERO-COMMANDER
                                             SA-2322-11
     FIGURE  1   AEERO COMMANDER AIRCRAFT OF
                COLORADO STATE UNIVERSITY

-------
of the right angle of the flight track to the rivers; when the track

slants across a river a slight drift in position alters the distance

between checkpoints.  For the August 1972 flights the CSV aircraft was

operated  from the Alton Municipal Airport near the northern end of the

flight track.  During April 1973 the aircraft was operated from the

Spirit of St. Louis Airport near the western end of that flight track.

The checkpoints for both flight tracks that were used in the final data

reduction are illustrated in Figure 2.  Also illustrated along the

August flight track are the positions for which a detailed time series

analysis of data for 9 August 1972 was performed (discussed later).

Although data were recorded in the time domain, checkpoints were used

to convert all data to the distance domain.  In this way variations in

ground speed along the two legs of the flight were effectively removed

by changing the data density per unit distance.  Table 1* contains a

listing of all flights conducted during the program.

      Under a subcontract with Colorado State University, its pilot

and technician obtained the following measurements from the aircraft:

      (1)  Subtrack photographs with two Hasselblad 70 mm cameras

      (2)  Total downwelling solar irradiance with an Eppley Pyranometer

      (3)  Total upwelling solar irradiance (reflected solar radiation)
           with a Yellott SOL-A-METER (solarimeter)

      (4)  Surface temperature with a Barnes PRT-5 radiometer (8 to 13 |j,m)

      (5)  Wet and dry bulb temperatures at flight altitude.

Aerial cameras were employed to document surface characterisitcs of

regions used later for time series analysis, to verify checkpoint
*
 Times shown in this table are flight starting times in contrast to
the text and figures where some average time is used to designate a
specific flight.

-------
                                         •  Flight Check Points

                                         x  Locations For Time Series Analysis
                                                                          SA-2322-12
FIGURE 2   FLIGHT TRACKS,  CHECK POINTS, AND  LOCATIONS SELECTED
            FOR  HARMONIC ANALYSIS OF  DATA
                               10

-------
                                    Table  1
              CHRONOLOGICAL SUMMARY OF AIRCRAFT OPERATIONS IN ST. LOUIS
     DATE

9 August 1972
11 August 1972
12 August 1972
17 April 1973
START
Local Time?
0345
0555
0850
1120
1330
1600
1845
2100
0030
0330
0630
0900
1130
1400
1630
FLIGHT
TRACK t
N-S
N-S
N-S
N-S
N-S
N-S
N-S
N-S
N-S
N-S
N-S
N-S
N-S
N-S
N-S
1100
1400
N-S
E-W
23 April 1973


24 April 1973



27 April 1973
1630
1900
2200
0100
0400
0600
0830
1115
E-W
E-W
E-W
E-W
E-W
E-W
E-W
E-W
                                    COMMENTS
                                              Photographs
                                              Aircraft malfunction; flight aborted
Photographs
Photographs
Photographs
Photographs ; rain showers along
flight track

Check flight

PRT-5 test flight

Photographs
                                              Photographs ; extensive cloudiness
                                              Extensive cloudiness

                                              Photographs; rain showers developed
 August times are Central Daylight Time; April times are Central Standard Time.

 tSee Figure 2
                                        11

-------
locations and actual tracks followed in flight,  and to assist in data




interpretation as a function of time of day.   Good 70 mm film trans-



parencies were obtained over most of the August  flight track; selected




prints over specific areas during the flight  of  9 August are presented



later.  Two Hasselblad cameras were used to obtain overlapping photographs




at a 1220 m flight altitude at typical cruising  speed, but complete




coverage over the 90 km track on a single flight leg required changing




film during flight.  With only a single technician aboard the aircraft,




other duties normally would not allow sufficient time for changing film.





      For the April 1973 flights, along the E-W  track shown in Figure 2,




two additional Hasselblad cameras and an observer were added to the flight




program.  No complete daytime series of observations was acquired during



the April program, although rather complete photographic coverage of the




entire E-W track was obtained during an unsuccessful flight near noon on




27 April.  Despite the inferior quality of some  of those prints, land-use




forms and flooded areas (especially along the western end of the track)




were clearly depicted.  In general, the surface  types were very similar




to those covered along the other track for the August flights.





      Data from the pyranometer and solarimeter  were recorded onboard on



separate Moseley strip-chart recorders.  The PRT-5 radiometric measurements,



dry and wet bulb temperatures, and time were recorded on a seven-channel



PEMCO analog recorder.  One of the channels was  used as an event marker



to indicate overflights of checkpoints along the flight track.





      Albedos were determined simply as the ratio of upwelling to down-




welling irradiance.  Although the pyranometric measurements of downwelling




irradiance were associated with a time constant  on the order of 15 seconds




(about 1 km travel distance), such rapid variations in the downwelling



irradiance during clear-skies were not anticipated.  The time constant




for upwelling irradiance measurements, on the other hand, was on the
                                   12

-------
order of milliseconds (similar to the time constant for the PRT-5 radio-



meter).  For the April flights a narrow-angle (20-deg) solarimeter was



added to provide more restricted views that were more compatible with the



radiometric surface temperature scenes acquired by the PRT-5.  Furthermore,



for the April program, the field of view of the PRT-5 was expanded from



4 to 20 degrees with a lens.  Thus, the infrared radiometric resolution



was degraded while the spatial resolution of the reflected solar radiation



measurements was increased for compatibility.





      Figure 3a shows (in relative ordinates) samples of recorded



radiometric temperature response as measured along the April flight track



under cloudy skies on 17 April (not a data run).  Although the two trace



segments were not acquired simultaneously, they successfully illustrate



that the coarser resolution provides appropriate data for comparison



with solar measurements.  Figure 3b provides a comparison of the narrow-



angle and wide-angle solarimeter data from a flight altitude of 460 m.



In absolute form the data from the narrow-angle solarimeter (converted to



hemispheric) appear to read lower than the wide-angle data.  Because of



residual uncertainties in the calibration data, results in Figure 3b are



plotted in normalized fashion.  It is apparent that the enhanced



responsiveness of the narrow-angle solarimeter makes it preferable to the



wide-angle instrument.





C.    Data Processing





      1.   Solar Radiation





           Records of the downwelling irradiance measurements at the



surface were digitized manually and instrument calibration data were



applied to the digitized data.  Strip chart records of the solar



measurements aboard the aircraft were checked for quality, timing, and



zero-reference drift.  Airborne strip chart speeds were maintained at



2 in/min;  pyranometer data were recorded over a 10 mv amplitude range





                                  13

-------
  -1.0
   0 5
cc
o
  -1.0
CJ
z
<

o
LU
LU
tr
o
00
N -0.5
_j
<
                                                               /\
          NARROW ANGLE
               10
                        20
                                 30       40

                                    RANGE—km



                                     (b)
                                                    50
                                                             60
                                                                      70
                                                                    SA-2322-13
   FIGURE  3   VARIATIONS  IN RESPONSE  (a)  BETWEEN 4-DEGREE AND 20-DEGREE

              RADIOMETRIC MEASUREMENTS OF  SURFACE TEMPERATURE  AND

              (b) BETWEEN WIDE-ANGLE  AND NARROW-ANGLE SOLARIMETER

              MEASUREMENTS OF SURFACE  REFLECTANCE
                                     14

-------
whereas solarimeter data were expanded to a full-scale 5 mv range.



Fifteen-second averaged samples were punched on computer cards for



processing on SRI's CDC 6400 computer.  Calibration, conversion to the


                9    —1
units of cal cm'* min  , albedo calculations, and graphing of results



were accomplished on the computer in conjunction with the CDC 280 CRT



display and microfilm system.  Most difficulty was encountered with the



data plotting program.  It was necessary to identify data points closest



to available checkpoints on each flight.  Subsequently, the spacing of



data points between checkpoints was preset in accordance with the known



range between checkpoints.  In this way it was possible to align data



from the two flight levels over the proper points in range and ensure



correspondence with data from the PEMCO recorder.  The biggest difficulty



with the river crossings occurred when the flight track from one leg



strayed to the east or west of the other leg (on the August flights).



Such a drift would force the appearance in the data plots of a misplacement



in the river locations on a fixed range scale.  The alternative was to



shift the river crossings to exactly the same range points with an



attendant artificial compression or expansion of data points over short



stretches.  In final form the upwelling and downwelling irradiances and



the albedos along a single flight leg were plotted (using a three-point



triangular slit function) separately from those along the other flight



leg.   Data from the return leg were plotted in reverse order so that



the ordinates and abscissas of both graphs matched for easy comparison.



Listings of all plotted data points were obtained also as a function



of range.





      2.   Surface Temperature





           Data from the analog tapes from the PEMCO recorder were



digitized  at a high rate at Colorado State University.   Resultant



digital tapes were processed on the CDC 6400 at SRI.  First,  revised



digital tapes were prepared, during which time one-second averages of




                                  15

-------
the digital count in each channel were computed, stored and listed.




These listings were used to screen the data and assign checkpoint



locations.  During the final computer run the digital counts from the




intermediate tape were averaged over five-second intervals, converted to




volts and then to temperature, and plotted on the same abscissa (range




along flight track) used to plot the solar data.  Range zero always



referred to the first checkpoint on the flight track (the northern end




for the August flights and western end for the April flights), the




extreme right side of the plot always contained data from the southern-




most (August) or easternmost (April) end of the flight track.  Two




graphs were plotted for each flight, but instead of separating them




according to flight altitude (leg) as with the solar data, one graph




contained the surface temperatures measured from the PRT-5 during both



flight legs and the other graph contained the dry bulb temperature for




both flight legs.  The arrangement was selected because of the usefulness



of direct comparison of temperature measurements of the same type from



different altitude.  Since the surface temperatures measured from both




altitudes were expected to be extremely close in magnitude, 10°C was




added to all measurements from one flight altitude to displace the



record on the plotted graph.





           The most serious data reduction problem encountered was the



zero drift on the particular PEMCO recorder used, apparently as a result



in part of inadequate warm-ap during the frequent short-duration flights.




Thus, while adequate calibration data were available for converting




voltages to temperature, it was extremely difficult to obtain a reliable




quantitative zero reference to convert digital count to voltage.   During




the April 1973 flights the situation was improved by installing voltage




boxes to supply known voltages to all channels at least three times



during a flight.  For the Aagust 1972 data, corrections had to be based




on post-flight laboratory displays of zero drift, apparent changes in






                                  16

-------
river surface temperature on a given flight, and on observed back-




ground changes in the digital count on the event channel when not in



use.  Deducted time-dependent changes in digital count to all channels




had to be added during the final processing stage.
                                 17

-------
                    Ill  METEOROLOGICAL CONDITIONS








A.    9 August 1972





      During the afternoon of 8 August 1972 a weak frontal system passed




through the St. Louis area.  A following period of at least 36 hours




of clear weather was anticipated.  It was decided to initiate flights




at 0300 CDT on 9 August 1972; at the time light winds from the NNW




prevailed.  A minimum (shelter-height) surface temperature of 15°C




occurred at about 0540 CDT.  By 0900 surface winds had shifted toward the




NE.  Some cirrus clouds were present in the morning and some cumulus




activity occurred in the afternoon.  The flight initiated at 2100 CDT




was aborted because of an aircraft alternator malfunction.  This




incident terminated the mission during what subsequently developed as



the best opportunity for a 24-hour period of observation under reasonably




steady meteorological conditions.  Particle loading of the atmosphere, as




revealed by time-height displays of lidar backscatter signals, was



relatively light for the area for this time of year.





      Figure 4 shows the total insolation as well as the atmospheric



infrared irradiance at the Granite City surface site on 9 August 1972.



The influence of morning cirrus clouds and small afternoon cumulus clouds




on the downwelling solar irradiance is apparent in the trace.  The



maximum in the curve of atmospheric radiation occurs more than an hour



after the maximum incoming solar radiation, but the trace generally




shows little variation.  An even greater phase lag was anticipated.  A




careful examination of the PIR data suggested that measurements of the




atmospheric radiation were not reliable over short time scales; apparently,




the instrument responded to short-term solar heating of the instrument




window rather than solely to the true local infrared scene aloft.





                                  19

-------
                                                                         r    8
                                                                                     <
                                                                                     (fl
                                                                                  I
                                                                                  (-
                                                                                  H
                                                                                  I
                                                                                  o
                                                                                  o
                                                                 o

                                                                 LL
                                                                 CC

                                                                 CO
                                                                 _l
                                                                 <
                                                                                             o
                                                                                             N
                                                                                             IT
                                                                                             O
                                                                                             X
                                                                                             Q
                                                                                             O
                                                                 <  CN

                                                                 Q  O>
                                                                 DC  O
                                                                 UJ  D
                                                                 I  <
                                                                 Q.
                                                                 CO  O)
                                                                 O    .
                                                                 5  00
                                                                 I-  n
                                                                                             en
                                                                                             <  t

                                                                                             0°
                                                                                             CO  UJ
                                                                                             •*r

                                                                                             LU
                                                                                             DC
            CO
            o
10
o
CN
O
  UIU1    _LUS  |E3	
L ~      c~
                               20

-------
B.    11 August 1972





      On 10 August the region of highest pressure in the area had



shifted to the southeast, enabling a return flow of warmer air with



higher humidity from the south.  The forecast for 11 August called for



fair weather but with cumulus activity in the afternoon leading to



perhaps a 4/10 sky cover.  Inasmuch as the flight track used on 9 August



was suitable, another series of observations was initiated with the first



flight at 0030 on 11 August.  At that time surface winds were light from



the SSE.  A minimum temperature of about 17.4°C was observed at 0530.



By daylight a considerable cover of cirrus clouds prevailed but, since



solar heating was evident, the mission continued.  Surface winds increased



during the morning with directions shifting through S to SSW and then



to SW.  At the same time the cirrus cover dissipated.  The winds subsided



in the afternoon but small cumulus began forming by 1330.  By 1530 winds



had become variable and considerable convective activity had increased



the cumulus cloud cover to about 5/10.  The maximum temperature at the



Granite City site was 32.2°C.  At 1545 CDT cumulonimbus clouds developed



nearby and extended almost overhead by 1630, the starting time of



afternoon flight.   Shortly thereafter the winds at the Granite City site



shifted to the N and then the NE while remaining light.  Some showers



had occurred in the city and the mission was aborted after the 1630 flight.





      Figure 5 shows the total solar radiation and atmospheric infrared



radiation measured at Granite City during the daytime of 11 August.  The



curve for total insolation illustrates the deterioration of the forcing



function of the surface energy balance near 1600.  Although particle



loading of the atmosphere was somewhat more extensive than on 9 August



1972,  11 August was not a day with strong pollution.
                                  21

-------
                                                                             8    2
                                                                                I-

                                                                                I
                                                                             rs  <
                                                                             -  Q
                                                                                O
                                                                                o
                                                                                         U
                                                                                         LL

                                                                                         CC
                                                                                         O
                                                                                         N

                                                                                         cr.
                                                                                         O
                                                                                         Q

                                                                                         CJ
                                                      5  2
                                                                                         cc
                                                      Q.  T-
                                                      CO  ^
                                                      O   .



                                                      <  ^
                                                                                         CO  LU
                                                                                         LU
                                                                                         DC
o
CM'
           m
           a

lea  —  3DNVIQVUHI
                                             22

-------
C.    23 April 1973





      A second  experimental  program in the St. Louis  area was  arranged




with Colorado State University to permit availability of their aircraft



during a two-week period.  Unfortunately, the desired optimum weather



conditions did not prevail during this period.  Unusually severe flooding




affected the general area during the stay, thus rendering somewhat




atypical the rural-urban differences in surface characteristics.  No



satisfactory 24-hour periods for the observational program occurred




during the first week.  During the following week the forecasting




problem became very difficult due to periodic surges of moist air aloft



with upper-level cloudiness, sometimes  with light rain.  As events




developed, a suitable 24-hour period would have been possible following




the rain on the night of 22 April 1973.  The forecast for 23 April was



for fair weather until late in the day again.  However, when it began




to appear that overcast conditions would not occur until sometime on




24 April it was possible to initiate a series of observations late in




the day of 23 April.  It was concluded that at least a series of




observations during the cooling period following a dry daytime period




would be worthwhile.  The first flight could not be started before 1630




CST, at which time skies were clear with relatively light winds from



the WNW.   By about 0000 on 24 April cirrus clouds began moving in over



the surface site at St. Louis University.  Before sunrise winds shifted



to the NE, and eventuall more to the E.  By 0900 on 24 April a middle



and high overcast condition had developed and further flights were




cancelled.  Inasmuch as only a very limited period of  insolation was




recorded before sunset and the nighttime record of atmospheric radiation




was very steady (with only a slight increase from cirrus clouds after




midnight), these observations were not presented herein.
                                 23

-------
                       IV  AIRCRAFT OBSERVATIONS








A.    Solar Data





      Graphic records of all of the processed solar data obtained during



the flight days of 9 August and 11 August 1972 are presented in the



Appendix.  Data samples illustrated in Figure 6 refer to the 1400 CDT



flight of 9 August.  The origin of the range scale shown in Figure 6



corresponds to the northernmost checkpoint in Figure 2.  A broad portion



of the Mississippi River was crossed at a range of about 10 km.  Some



irregularities in the measured downwelling solar irradiance in Figure 6



result  from clouds existing above the aircraft.  The dip in downward



flux measured from the 460 m altitude at the 50 km point in range is



associated with an artificial maximum albedo; this is the result of



cloud shading the pyranometer but not the target area on the surface.



A striking feature of the illustration, which is typical of all obser-



vations, is the lower albedo over the urban area (roughly, between 33



and 45 km range) relative to the surrounding suburban and rural areas.



Although the spatial difference in albedo is only a few percent absolute,



the reduced urban albedo surely is significant in terms of the surface



energy budget.  More of the solar radiation reaching the urban surface



is available for heating the surface.  In addition, the lack of sig-



nificant evapotranspiration processes over the urban area means that



even more solar radiation is available for heating.  A complete



explanation of the lower urban albedo requires a more careful examination,



but the observed differences are probably accounted for by the structural



"trapping" of solar radiation and shading of other surfaces in the urban



area, combined with a surprising number of relatively dark urban roofs,



areas with reflective soils outside the urban area, and an increase in




                                  25

-------
  7  2.0
  0  1.0
  <
  Q
  <
  DC
  ^  0.5
                                   '    I   '
                                URBAN I
                                CENTER    ,\    ; •
                                                        ALBEDO
                       DOWN
                         UP
                     20
                                   40
                                                60
                                              km
                                    RANGE

                         (a) FLIGHT ALTITUDE = 460 METERS
                                                             80
                               17.5

                               15.0

                               12.5
                            100
     1.5
     1.0
  tr
  E  0.5
                                URBAN
                               CENTER
                                                       ALBEDO
                       DOWN
                         UP
                                   I
                     20
                                   40
  60
km
                                    RANGE

                        (b)  FLIGHT ALTITUDE = 1220 METERS
                                                             80
                              17.5

                              15.0

                              12.5
                                                                          100
                                                                      SA-2322-17
FIGURE 6    AIRCRAFT SOLAR MEASUREMENTS, 1400  CDT  FLIGHT, 9 AUGUST 1972

                                        26

-------
 reflectance over rural areas at  wavelengths  just  beyond  the  visible  range.



 From higher altitude the albedo  variations could  appear  more uniform,



 but would depend on the scattering/absorption properties of  the  urban



 aerosols.





       Originally it was hoped to perform a detailed examination  of



 possible  diurnal variations  in albedo (as function of surface type)  as



 well as height  variations in albedo as determined from the aircraft



 observations at two altitudes.   It  is possible, for example,  that as the



 sun's elevation and azithmuth change during  the day the  complex  changes



 in shading within urban structures  could result in a diurnal variation of



 albedo.  Both height and orientation of structures would be  important.



 However,  other  factors (including surface wetness) also  are  involved in



 diurnal variations and the accurate repetitive measurement of small



 changes in albedo is a difficult task that requires a considerable body



 of data before  final conclusions can be drawn.





       The deduction of temporal  changes in surface albedo on the basis



 of aircraft observation introduces  some uncertainty due  to time  changes



 in atmospheric  attenuation and turbidity. An attempt to remove  this



 uncertainty was accomplished by  overflights  of each site at  two  altitudes



(460 m and  1220  m)  during each flight.   Presumably,  consistent identifiable



 differences in  the measured  albedos could be used to adjust  to an



 appropriate surface albedo.   Unfortunately the differences again are



 small and  are subject to factors other than  atmospheric  attenuation.



 Thus the  periodic  observations from the two  flight altutudes failed  to



 establish  any significant height or time variations (very low sun angles



 excluded)  of surface albedo.   Only  the horizontal variations were



 significant and were related to  variations in reflected  solar radiation.





       Time differences in the overflight of  a given portion  of the track



 by a single aircraft at two  altitudes complicates the interpretation of
                                   27

-------
changes in measured solar radiation.  Along the near end of the track,

overflight at the second altitude may occur as much as 50 minutes later;

the time delay is much shorter at the far end of the track.  During this

period of delay, time changes in the downwelling solar radiation (and

possibly the albedo) occur regardless of atmospheric changes.  With any

cloudiness aloft, changes in cloud locations and in the cloud shadow

location will influence the relative solar measurements over a given

site.  Furthermore, the actual scene being viewed changes with aircraft

altitude.  As the altitude is increased the viewed area increases rapidly

and the type of surface viewed is changed by an amount dependent on the

homogeneity of the surface.  In addition, even the same objects in

the field of view are not viewed at the same sun angles, except at the
         jt
subpoint,  and differences in shading occur.  How these factors influence

the deduced atmospheric attenuation during the course of the day may be

difficult to infer unless experiments are first conducted over a truly

homogeneous surface of sufficient size to fill the field of view at

both flight altitudes.


      Although the observed relative spatial variations in albedo were

real, absolute values may have been biased by calibration inaccuracies.

Comparisons of surface and aircraft measurements of incident solar

radiation indicated that the downwelling irradiance interpreted from

aircraft measurements was too large.  Assuming the validity of upwelling

irradiance measurements on the aircraft, the absolute magnitudes of

calculated albedos apparently were too small.


      Figure 7 illustrates the downwelling irradiance measurements on

11 August 1972 at flight altitudes of 460 m and 1220 m.  Differences in

the measurements over urban and rural locations were insignificant during

the time period illustrated.  The indicated maxima in incident solar
 Subpoint refers here to the point on the ground directly beneath the aircraft,


                                  28

-------
             1220 m FLIGHT ALTITUDE
                                 460 m FLIGHT ALTITUDE
                10
                           11          12
                            CDT 	 hours
13          14


    SA-2322-18
FIGURE 7    HEIGHT  VARIATIONS OF MEASURED INCIDENT SOLAR
            RADIATION,  11 AUGUST 1972
                              29

-------
radiation measured at 1220 m and at 460 m are 1.76 and 1.66 cal cm 2



min"-1-, respectively.  The maximum incident solar radiation measured at



the surface (at the Granite City site) was only about 1.3 cal cm~2 min"1.



If it is assumed that complete homogeneity existed in the atmosphere



below 1220 m and that the surface measurement was correct, then it must



be concluded the absolute magnitudes of the aircraft measurements were



overestimated by about 20%.  If, in addition, the aircraft solarimeter



measurements were assumed to be accurate, then the inferred albedos



should be increased by about 25%.  Relative differences, which are small,



would be increased by the same amount.





      Even with residual uncertainties in absolute magnitudes of solar



components it is possible to examine relative variations in terms of



ratios of departures from average to average.  Data from both legs of



the 1700 CST flight on 23 April 1973 are presented in such nondimensional



ratios in Figure 8 for downwelling and upwelling irradiances and the



inferred albedo.  Only wide-angle solarimeter data were analyzed for



presentation in Figure 8.  The first leg (eastbound) of the flight was



flown at an altitude of 460 m; a loss of pyranometer data occurred during



this leg.  Despite the data dropout, the decline in the normalized curve



for the downwelling irradiance clearly reveals the reduction in incident



radiation with decreasing solar elevation during the 22 minutes of flight.



On the return leg (westbound) at an altitude of 1220 m, the decreasing



solar elevation results in minimum incident radiation at the zero range



on the flight track.  The influence of small clouds is most evident in



the traces for the 460 m flight; although the downwelling irradiance is



reduced by the clouds the underlying surface is not shaded simultaneously



so that albedo maxima result.  Flooding of areas surrounding St. Louis,



especially at the western end of the flight track, reduced the albedo



but an albedo minimum is apparent again over the urban area.  In general,



the surface albedo ranges from about 10% below average to 10% above average.





                                  30

-------
1.5
Z
m 1 0
LU
oc
3 0.5
LU
DC
O
C/J
£ - 0.5
N
<
DC
O
Z
- 1.5

0

A: ALBEDO
i * jX
-- 1 ^ ' * x "v * * s
:"' ""'-—
_ _
D: DOWNWARD FLUX
'""^11 i i 1.1 J
L \A^ ~~ 	 .
— _

f^.' ^"^^ ^ 	 ..-'•N _
U: UPWARD FLUX
I.I, .1.1.1.1
10 20 30 40 50 60 70
RANGE — km

(A - A)
A


(D - D)
D


(U - U)
U



                                                                             1.0
                                                                           - 1.0
                          FLIGHT ALTITUDE = 460 METERS

1.5
CO
Z
LU
5 1.0
LU
DC
D

< 0.5
LU
2
< 0
0
2 - 0.5
N
CC
O
Z
- 1.5

C

I ' I ' I ' I ' I ' I ' I
— —
A: ALBEDO
' " ** *. «
.' "*---*...--'' " ""-' "-' x---.-
.


— —
D: DOWNWARD FLUX
	 	 . 	 N 	 ^^^^
: — 	 	 ^~
— —
U UPWARD FLUX
/ ~ 	 "" ~
i — —
I . I , I , I , I . I > I
10 20 30 40 50 60 70
RANGE — km



(A - A) + , n
A





(D - D)
D


-------
B.    Surface Temperature





      The measurement of surface temperature with the PRT-5 radiometer



also was accomplished at the two flight altitudes.  In principle,  with



proper allowance for actual time changes in surface temperatue during



the overflights at two altitudes, the affect of atmospheric attenuation



on the measured surface temperatue can be inferred from the difference



observed from the two flight levels.  However, the same factors that



influence the albedo measurements at different heights also complicate



the interpretation of temperature differences for the same site.  Surface



temperatures are strongly influenced by changes in solar heating;  rapid



fluctuations associated with shadows of cumulus clouds are much larger



than differences of radiometric temperature associated with atmospheric



attenuation.  Of course, surface inhomogeneities contribute to variability



in the PRT-5 records; nevertheless, the general picture that emerges is



consistent with albedo measurements and expectations.  Urban centers



show higher temperature than the surrounding rural areas, as illustrated



in the sample shown in Figure 9.  Because of the small differences in



radiometric surface temperature with flight altitude, the data from the



1220 m altitude have been displaced upward 10°C on the graph.  Summaries



of temperatures at selected sites  along the track for each flight time



were used in the time-series analyses discussed below.





      Figure 10 illustrates the departures of the PRT-5 measurements of



surface temperature from their means during each leg of the 1700 CST



flight on 23 April 1973.  The 460 m flight altitude (flown first)  was



associated with an apparent average surface temperature 1.6°C warmer



than that for the 1220 m flight altitude.  Consequently, the flooded area



around the Missouri River (see flight track in Fig. 2), represented by



the broad minimum near the origin of the track, appears with a larger



temperature departure from normal in the 460 m flight record than in the



1220 m flight record.  The same is true for the sharp minimum characterizing




                                  32

-------
   50
   40
in
CC
   30
IT
ill
a.

u
t-
o
<
u.
cc
D
OT
I-
flC
a.
20
   10
                                  URBAN I
                                        —  Measured From 460 Meters Altitude


                                        —  Measured From 1220 Meters Altitude, 10°C Added


                                             I	I	I	I	!
                     20
                                    40              60

                                        RANGE—km
                                                                     80
                                                                                  100
                                                                              SA-2322-20
    FIGURE 9   AIRCRAFT RADIOMETRIC SURFACE TEMPERATURE MEASUREMENTS,

                1400  CDT FLIGHT, 9 AUGUST 1972
                                           33

-------
o
O
oc
UJ
(T
D
UJ
Q

UJ
QC
D
H
<
DC
HI
Q.

UJ
H
I-
CE
Q.
	Flight Altitude 460 Meters

	 Flight Altitude 1220 Meters
  - 5.4  -
      FIGURE  10    NORMALIZED AIRCRAFT RADIOMETRIC SURFACE  TEMPERATURE
                    MEASUREMENTS, 1700 CST FLIGHT, 23 APRIL 1973
                                          34

-------
 the crossing of the Mississippi  River near the  center of the  track.




 These results are reasonable since water body temperatures  remain



 relatively uniform over short time intervals due to the large specific




 heat and effective mixing depth  of the water.  Thus,  after  accounting




 for the time change of the normal temperature for each track, the water




 temperatures measured from both  altitudes differ by less than one degree




 and indicate that the atmospheric influence on  the measurements was




 small at those localities.   The  temperature departures above  normal  are




 restricted to the urban area, which is significantly warmer than the



 rural areas to the east.   Records from the two  flight altitudes are  in




 excellent agreement except for an unspecified feature in the  western




 portion of the urban area.






      Apparent  spatial variations  of  the radiometric  surface  temperature




could be  influenced by marked gradients in surface emissivity (in the




10 to 12  |j,in spectral region)  or by significant variations in  atmospheric




attenuation.  No  evidence is  available to support a significant emissivity




variation that  accounts for observed horizontal temperature differences.




Some insight into the possibility of differential atmospheric attenuation




is provided by  the  airborne PRT-5 measurements from two  altitudes.





      Data acquired on 9 August 1972 were averaged over  two segments




of flight track representative of urban and rural surfaces.   Results



for the two flight  altitudes  are illustrated  in Figure lla,  where smooth




curves have been drawn through data points derived from  seven flights.



The pronounced daytime increase of the urban  surface  temperature relative




to the rural surface temperature is clearly depicted.  In all observations,




the surface temperatures measured from the lowest altitude exceed those




measured from the highest flight  altitude, as anticipated by  the presence



of atmospheric attenuation.  Only for the 1400 CDT flight does the urban




temperature difference with flight altitude significantly exceed the
                                  35

-------
LU
CJ CJ
DC
D
in
DC (-
H <
IJJ DC
5 LU
40

35

30

25

20

15

10

 5
       •^** ^" *^ Flight  Altitude 460 Meters
                    Flight  Altitude 1220 Meters
                                                                             URBAN
                                                                             AREA
       0400      0600      0800       1000       1200      1400
                                            CDT — hours
                                    (a)  9 AUGUST 1972
                                                                     1600
                                                                               1800
                                                                                         2000
   LU
   CJ CJ
        30
        25
   LL
   DC
   to LU  20
DC h-
H <
UJ CC
5 LU
21
Q £
< h-
tr
        15
        10
                                                I       I       I       I      I
                                           ^? TZ !^ Flight Altitude 460 Meters
                                                        Flight Altitude 1220 Meters
                  RURAL
                   AREA
                 1800
                              2000          2200          0000
                                               CDT — hours
                                     (b)  23-24 APRIL 1973
                                                                       0200
                                                                                      0400
FIGURE  11
                                                                               SA-2322-22

           URBAN AND RURAL  SURFACE  TEMPERATURE  VARIATIONS WITH TIME

-------
rural difference.  This suggests either greater attention in the urban




atmosphere than in the rural atmosphere at 1400 CDT, with a suppression




of the urban-rural surface temperature contrasts, or reduced attenuation



below 460 m over the urban area at this time.  (The same feature was




not apparent at 1400 CDT on 11 August 1972.)






      For the evening and night hours of 23 April 1973, PRT-5 data along



the second flight track also were averaged over urban and rural areas.




Results illustrated in Figure lib show slightly more atmospheric




attenuation over the urban area throughout the period.  Presumably, the




excess of urban surface temperatures over the rural surface temperatures



should have been larger than those measured from the lowest flight




altitude.  Unfortunately, no data were available on differences in



particle loading of the atmosphere over the two areas.





C.    Air Temperature





      Included in the aircraft observations were the air temperatures




along the two flight altitudes.  These data, although not specifically




required for the surface analysis, are significant for several reasons.




First, they provide a quick graphic display of thermal stability or




changes in stability along the flight track.  Second, harmonic analysis



may be used to examine differences in the vertical  exchange  of  sensible




heat in the boundary layer.  Finally, they are useful in assessment of



atmospheric absorption and emission of infrared radiation,  especially




when combined with humidity measurements.





      Samples of air temperature measurements at the two flight altitudes




are shown in Figure 12; other data are included in the data summaries




presented in the Appendix.   The horizontal profiles of air  temperature




are sensitive to the relative accuracy of the measurements,  to slight




changes in flight altitude, and to the possibility of differential
                                 37

-------
  25
  20
LU

DC
cc
til
Q.


uj


DC
  15
   10
                                460 METERS ALTITUDE
                                1220 METERS ALTITUDE
                   20
                                  40             60

                                     RANGE — km
                                                                80
                                                                               100



                                                                         SA-2322-23
    FIGURE 12   AIRCRAFT AIR TEMPERATURE MEASUREMENTS, 1400 CDT FLIGHT,

                9 AUGUST 1972
                                       38

-------
advection along the tracks.  Differences in the stability over urban



and rural areas during different times of the day are of special interest,



but often small in magnitude above the surface layer.  The pronounced



influence of convection on the temperature differences at the two flight



levels is illustrated by the relatively large temperature differences



in Figure 12.  On many of the records slight changes in temperature with





time (during the period of  flight)  are noticable.   On the other  hand,



spikes that  appear in the reduced air temperature  data represent noise.
                                   39

-------
                      V  CLIMATONOMICAL ANALYSIS


A.    Climatonomy Theory

      Professor Heinz Lettau was prompted in 1954 to coin the term

climatonomy in order to emphasize quantitative aspects of the subject

and to avoid misconceptions that might be associated with the word

climatology.  The distinction is intended as an analogy to the development

of modern astronomy from the earlier astrology.  Thus climatonomy denotes

the use of numerical models to solve the local surface energy budget

equation.  A synopsis of climatonomy theory is presented below.  Surface

energy budget theory expresses the principle of the conservation of

energy in the partitioning of the effective insolation at the earth-air

interface.  For the case of local homogeneity, the surface energy budget
is given by

                 F0 = LW0T - LWol + S0 + Q0 + E0 + Po,              (1)

where,

      F  = solar forcing function (cal cm~2 min~^);  the effective short-
           wave radiation at the surface,

    LWO| = upwelling longwave radiation at the surface
    LW0i = downwelling longwave radiation at the surface

      So = subsurface heat flux density

      Q0 = atmospheric heat flux density
      E0 = evaporative heat flux density

      P0 = photosynthetic heat flux density.

By definition,  heat flux away from the surface is defined as a positive

flux.  For the urban surface, photosynthetic energy transforms can

usually be ignored, while on the overall average they may account for

                                  41

-------
5% to 10% of the available solar energy (Van Wijk) .3  In this exploratory


study we have chosen to ignore this term, although further work should


seek to evaluate this impact of vegetation on rural-urban climatic


differences.



      In climatonomy, the energy budget is examined over basic meteoro-


logical periods (e.g., diurnal and annual) through the use of "Fourier


synthesis."  Thus each term in Eq. (1) is represented by a mean value


and harmonics.  Expanding each term in Eq. (1) we obtain


                     m
           Fo = Fo +£1 V'o cos >
(2a)
                	     m                           *
         LW0| = LW0|  +  E  A.jLW0t cos (int - 6.  + y.  )>             (2b)
                       •i=i                     i     i
                        m
         LWn| = LW I  +  T,  A LW | cos (int - 6  + 3  ),             (2c)
           0      °    i=l  i  o              i    i


                _    m

           S  = S  +   £  A S  cos (int - 6  + ilr  ) ,                 (2d)
            o    o   i=i  i o             i    i
                —
           Q  = Q  +  £  A Q  cos (int - 6  + cp  ) ,                  (2e)
            o    o   i=i  i o             i    i


                _    m

           E  = E  +  Z  A E  cos (int - 6  + V *) ,                  (2f)
            o    o   i=i  lo             i    i



where t is time, i is the harmonic order, and n is the basic frequency


when n = 2n/T and T is the basic period (i.e., one day).  In Eq .  (2),


A.O is the amplitude of the ith harmonic, 6. is the phase angle for the


ith harmonic of the forcing function, and ().  is the phase lag of the


various response functions to the solar phase.  In the analyses that


follow, zero time reference corresponds to midnight.  As usual, the


overbar denotes the time-averaged value over the basic period.



      A basic premise of climatonomy is that the primary response to the


solar forcing function is the surface temperature, and that the "climatic'


functions are secondary responses, via the surface temperature, to the


solar forcing function.  In other words, each of the climatic functions
                                  42

-------
can be expressed in terms of surface temperature and hence Eq. (l) may


be solved to yield a unique set of mean values plus variation of the


response terms.  It is thus appropriate to first introduce the Fourier


representation for the surface temperature and then to rewrite the


secondary response functions in terms of surface temperature, where


                	    m                    .,
           T  = T  +  E  A T  cos (int - 6 *) . and                  (3a)
            o    o   i=i  i o             i


                .	    m
           T  = T  +  E  (A.F /Z.) cos (int - 6  - £.),             (3b)
            o    o   i=i   101              i    i
where,
           Z  = A F /A T , and                                      (4a)
            i    i o  i o
           C. = \* - 5.-                                           <4b)



Furthermore,
                        m
         Lwt=LWt+  E  (TAT) cos (int - 6  - r  + v ),       (5a)
           o      o    i=i   i i o              i    i    i
                	    m
         LW I  = LW i +  E  (BAT) cos (int - 5  - C  + P ),       (5b)
           o      o    i=i   i i o              i    i    i

                	   m
           S  = S  +E  (VAT) cos (int - 8  - C  + A ),          (5c)
            o    o  i=l   i i o              i    i    i


                	    m
           Q  = Q  +  E  ($ A T ) cos (int - 6  - £  + cp ),         (5d)
            o    o   i=i   i i o              i    i    i


                	    m
           E  =E  +  E  (XAT) cos (int - 5  - t  + y ),         (5e)
            o    o   i=l   i i o              iii



where the following identities are introduced



           ALWf = rA.T,Y* = -C+Y;                       (6a)
            i   o1     110    i       11



                I—   Ao*-r
             AS=TAT,\j;* = -r+il;;                       (6c)
              io    iio    i       i    i
                                  43

-------
             A.Q  = $.A.T  , cp.* = - £  + cp  ;                       (6d)
              10    110    i       i    i



             A.E  = X.A.T  , X.* = - t.  + X.•                       (6e)
              10    110    i      'i    i



Introducing the identity (4a), Eq. (2a) is rewritten as


                    —   m
               F  = F  + 7  (Z A T ) cos (int - 6 ).                (7)
                o    o  i=i   i i o              i



      Lettau then introduces Eqs. (5) and (7) into (1), and expands the


cosine functions in terms of cosine and sine terms through the  trigon-


ometric identity:



cos (int-S -C +x ) = cos(int-5 )cos(f -x ) + sin(int-6 )sin(C -x  ).
          i "i  i             i'ii             ill

The basic cycle average equation is subtracted, leaving only a  departure


equation that is evaluated at int = 6  and int =6  + n/2 to yield two
                                     i            i

simultaneous, independent equations, where:



               -B sing  + r sinv  + ^f simlf  + $ sin  + X sinv
         ..       i    i    i    i    i	 i    i    i    i    i    . _N
     tan C,  =	(8)
         ' i    -B cosg  + J  cosy  + 1' cosijf  + $ cos^>  + X cosx
    and
,  Z.  = -B.  cos(£.-|3_.)  + r_cos(C.-Y.) + 1P. c°s( C .-^ . )
                             + § cos(C -co ) + X cos(C  -X  )•
                                i     "i  i     i     i  i



      In regard to the St. Louis experimental program,  it  is  important


to recall that not all of the amplitude and phase  terms are obtainable


directly from the observations, and hence we need  to consider  the


parameterization of these terms on the basis of identifiable  surface


features.



      Parameterization of the upwelling infrared flux  at  the  surface  is


straightforward through application of the Stefan-Boltzmann law,



                             LW T = eoT 4,                          (10)
                               o       o
                                  44

-------
where e is the surface emissivity and a is the universal Stefan-Boltzmann


constant (0.813 X 10~7 mly min'1 °K~4).  Upon introducing Eq. (10) into


Eq. (3a) and solving for the partial impedance and phase, we obtain
                           r  sr 4 LW T/T  , and                      (lla)
                            1       O   O



                           Y. = 0.                                  (lib)




      The partial impedance B. and phase fj  for the downwelling longwave flux


at the surface have not been parameterized here as they were obtained


through Fourier analysis of the continuous diurnal pyrgeometer measurements


made at the ground station.  Parameterization is possible through a wide


variety of empirical and theoretical approaches, such as the use of the


Angstrom ratio or Swinbank's method4 as discussed by Dabberdt5 , to


mention only two.



      The subsurface heat flux density is parameterized through the


application of Fourier's law of heat conduction--Eq . (12a) — and the


continuity equation for heat in the absence of sources and sinks — Eq .


(12b), where


                                  X 8T
                            S = -   — • , and                        (12a)
                                    dz
Here A. is the thermal conductivity (cal cm"1 °K   min"1) and C the


volumetric heat capacity (cal °K~1 cm"3) of the submedium.  Considering


the medium as a homogeneous conductor (dA/dz = dc/dz = 0) with time-


independent thermal coefficients OX/dt = dC/dt = 0), the partial


impedance T  and phase il;  are given as
           i            i


                               1/2        1/2
                    ^ = UCin)    = n(in) ' ,  and                  (12c)



                    1)1. = n/4,                                       (12d)





                                  45

-------
where ^ (cal °K~1 cm" sec ~-L/2) is defined as the thermal admittance.



      Parameterization of the atmospheric heat flux density is perhaps


the most difficult.  Lettau  presents a type of similarity approach


based on the near-surface vertical profile of potential temperature.


Both the partial impedance <[?  and the phase cp  are given in terms of a
                            i                i

characteristic number N. that is a unique function of the frequency,

                                                                 —W
aerodynamic surface roughness z , and the mean friction velocity V  ,
                               o

where
The partial impedance §. is then expressed as


                                  pC V*


                         $i = (a+bN )(l-lT>.                        (14a)
                                   i



The term M  expresses the magnitude of convective mixing relative to

                                                                —3T
mechanical turbulence; its absolute value is proportional to Q~~/V  and
                                                              o

is less than unity, and its sign is determined by that of Q .  For urban

       	5JT
areas, V  will usually be large because of the tall roughness elements

           #
and hence M  will be small.  Upon assuming bouyancy effects on turbulent


diffusion of heat as small in comparison with mechanical mixing, diurnal


variations of M* are similarly small  [(T/iM*)dM*/dt = 0] and Eq. (14a)


can be simplified accordingly, where

                                   pC V*


                                                                    (14b)
Lettau also gives an expression for the phase lag,



                           cPj = tan-l[—2— )                      (I4c)
                            p  = tan * I	  I
                            i         ^a+bNi f
where a, b, and c are semi-empirical constants.
                                  46

-------
      Since it would have been impractical if not impossible to directly
           u.
determine V  and zo along the flight path, these also must be estimated.

Values for z  were derived from an empirical relationship developed by

Kung,6

                    log   z  = -1.24 + 1.19 log h*,                 (15a)
                       10  o
where h* is the characteristic physical height of the roughness elements.

The term V* is, in turn, also derived from an empirical equation from

Kung based on the relationship between the geostrophic drag coefficient

C  and the surface Rossby number Ro,


                   C  = V*/V  = 0.174/(log10Ro - 0.81)              (15b)

                   Ro = V /z0f>                                     (15c)


where V  is the geostrophic wind and f the Coriolis parameter.
       g
      In this study a simplistic approach toward the parameterization of

evaporation has been taken with E  expressed in terms of Q  using the
                                 o                        o
inverse Bowen ratio Bo.  Thus,

                            X  = Bo$., and                          (16a)
      In the following section the reduction of the observations is
discussed in terms of the input requirements of the theory as well as
its application for the evaluation of the evaporative and thermal
properties of the surface throughout the region.

B .    Method of Approach

      Upon examining all the data collected during the August 1972 and
April 1973 experimental periods, it was decided to analyze in detail only
those data from 9 August.  This decision was based upon one very basic

                                  47

-------
and important criterion:  the theory as outlined earlier is only strictly

applicable when the basic (diurnal) cycle is controlled by the surface

features, and hence one should avoid periods having significant diurnal

trends and of course abrupt changes in the mesoscale atmospheric structure.
Only the 9 August data satisfied this requirement.

      In review, five basic types of meteorological data obtained on a

diurnal basis were available for climatonomical analysis:

      •  Downwelling longwave radiation at the surface station

      •  Downwelling solar radiation at the surface station

      •  Downwelling solar radiation at each of two altitudes from the
         aircraft

      •  Upwelling solar radiation at each of two altitudes from the
         aircraft

      •  Upwelling window-channel infrared emission (in terms of equivalent
         blackbody temperature) at each of the two aircraft altitudes.

In addition, available supplemental data sources included:

      •  Twice-daily boundary layer wind and temperature profiles from
         the NWS EMSU station located at the Gateway Arch

      •  Aerial photographs obtained along the flight path by the aircraft.

      While the aircraft observations were made continuously along both
of the two 90 km segments of each flight, it is desirable to isolate

portions of the flight track corresponding to distinctly different yet

individually homogeneous surface types and to thus obtain average

meteorological conditions representative of each.  Figures 13 through

21 are aerial photographs of each of the nine surface sites (see Fig. 2);

Table 2 identifies the various sites and briefly describes each.  It was

considered desirable to choose rural sites on opposite sides of the
urban core so as to examine possible skewness in the climatic distribution
                                  48

-------
that might arise from advection associated with the urban heat island.


The sites were carefully evaluated to ensure reasonable homogeneity


over a scale of several kilometers, thus minimizing the impact of


discontinuities in land use.  Digitized records of the hemispheric


solar radiation measurements from the aircraft were averaged over 15-sec


periods while 5-sec averages were obtained for the higher-resolution


infrared radiometer measurements of surface temperature.  Summaries of


these data over the various sites were used in the analysis of the


surface energy budget.



      The reduction of the surface observations of downwelling longwave


and solar radiation in terms of the requirements of the theory—Eqs. (2a)


and (2c)--is quite straightforward and involves only the direct application


of harmonic analysis (see for example, Panofsky and Brier).  Upon


recalling Eq. (2a) and expressing the absorbed solar radiation at the


surface (i.e., the surface forcing function) in terms of the insolation


F I and the surface albedo a, we obtain
 o


      F  = FI-Ft=Fj. (1-a) =                                  (17)
       oo     oo
                                 r—    m                  i
                           (l-a)  F | +  £  A.F |cos(int-6.)  ,
                                 |_ o    i=i  10          i J
when the albedo is time-independent.  Because the 9 August measurements


entail solar data on only five of the flights and because these were


obtained well above the surface, these aircraft observations were utilized


only to determine the albedo of each of the nine representative surface


types; the insolation measured at the surface station is used in the


evaluation of Eq. (17) under the assumption that spatial variations of


F I along the flight track were negligible on this day.  Values at 30-min
 o

intervals were taken from the analog trace, and the amplitude and phase


terms were computed for 24 harmonics;  the results are summarized in


Table 3.  Only the first and second harmonics are listed as together they


account for 98,8% of the total variance.


                                  49

-------
FIGURE  13   SITE R-1
 FIGURE 14   SITE R-2
FIGURE 15   SITE R-3
FIGURE  16   SITE R-4
                              50

-------
FIGURE 17   SITE R-5
FIGURE  18   SITE R-6
FIGURE  19   SITE R-7
                                           FIGURE  20   SITE R-8
                               51

-------
FIGURE  21   SITE R-9
         52

-------
                         Table 2

   DESCRIPTION OF SURFACE AREAS SELECTED FOR ANALYSIS


Site              Description             Range (km)t

 R-l      Mostly farmland; roadway;           23.8N
          some trees

 R-2      Mostly woods, some fields;          19.9N
          roadways

 R-3      New suburban housing tract          13.ON

 R-4      Commercial-industrial;              7.8N
          old residential

 R-5      Old urban residential               3.7N

 R-6      Old urban residential;              3.7S
          some light commercial

 R-7      Farmland                           12.5S

 R-8      Mostly woods and fields;            23.8S
          some farmland

 R-9      Mostly woods, some fields           33.7S
*Locations shown in Figure 2
tDistance (north  or south) of city center
                           53

-------
     The downwelling infrared flux density as recorded at the surface


station was also assumed representative of conditions at each of the


nine sites.  As above, the harmonic analysis of values at 30-min intervals


was performed in the evaluation of Eq.  (2c); the results are also listed


in Table 3.  In general agreement with the solar data, 95.6% of the


variance is specified by the first and second harmonics.



                                Table 3



         RESULTS OF HARMONIC ANALYSIS OF 9 AUGUST 1972 SURFACE

           OBSERVATIONS OF DOWNWELLING SHORT- AND LONGWAVE

                 RADIATION AT GRANITE CITY, ILLINOIS




              Parameter        Mean       i=l       i=2



           F  I (ly/min)        0.428      	       	
            o



           A F I  (ly/min)       —      0.646     0.235
            i o



           6. (rad)             	      3.429     0.555





           LW | (ly/min)       0.515      	       	
             o



           A LW J, (ly/min)      	      0.060     0.019
            i  o



           (3*. (rad)            	    - 0.305   - 0.405





     Determination of a daily average and the harmonics for the aircraft


observations cannot be obtained through standard harmonic analysis due


to the irregular spacing of the seven averaged data points representative


of each surface region as measured at each of the two altitudes.  Further-


more, the small number of data points,  and hence relatively large time


intervals, prevented the use of extrapolation methods.  Hence we evaluated


the applicability of a nonlinear regression routine available at the


Institute.  In this manner we specified the form of the Fourier series


                                   54

-------
 and  obtained the mean,  amplitude,  and  phase  that  best  fit  the data.  A


 two-harmonic function was  chosen,  resulting  in a  five-parameter fit


 to the  data:



         G(t) =  R  + R  cos(0.2618t-R  ) + R  cos(0.5236t-R ),        (18)
                  12              34              5



 where,



     R  = average value over the period (°C)




     R  = amplitude of 1st harmonic (°C)
      2



     R  = phase  of 1st harmonic (rad)
      O



     R  = amplitude of 2nd harmonic (°C)
      4



     R  = phase  of 2nd harmonic (rad).
      o



 The  form of  the  equation is directly analagous to that of Eqs. (2a)


 through (2f).  Prior to applying the method to the reduction of the


 aircraft data, the method was first applied in several test cases to


 evaluate its validity.  As a simple first trial, 14 irregularly spaced


 points  along a pure cosine wave with origin at 00 hours were analyzed


 using a three-harmonic form of Eq. (18).  The regression method requires


 initial guesses  (R*j) of each parameter; these were purposely chosen


 poorly:  R * = 0.9, R * = 0.1; R * = 0.15 rad, R * = 0.2, R * = 0.5 rad,
          _L          ^          o               45

R * = 0.2, and R * = 0.5 rad.  In  spite of the "bad"  initial values,
 6               7

 the routine  converged rapidly to provide the following results:   R  =


 1.2 X 10~4, R  = 1.000, R  = - 0.9 X 10~5 rad, R  = 2.2 X 10~4,  R  =
             2           3                      4                5

 0.6 rad, R  = 1.6 X 10~4, and R  =7.3 rad.  Although a good test of
          6                    7

 the method's validity in simulating a harmonic analysis, a more realistic


 evaluation entails the use of observed diurnal near-surface temperatures


under essentially stationary conditions.  Meteorological conditions on 9


August  in the St. Louis area satisfied this criterion.  Thermograph data


                                   55

-------
for this period were obtained from seven instrument shelters in the area




(see Fig. 22) of our operations; the shelters were maintained by the




Illinois State Water Survey (ISWS) as a part of Project METROMEX.8



These strip chart data were reduced to provide 24-hourly temperature




values at each station and then analyzed using both the conventional




harmonic analysis method for all 24 values and the regression method with




only eight values.  Data points chosen at times corresponding to the




times of the seven aircraft flights plus an additional value at midnight.




The results of the two sets of analyses are summarized in Table 4.




Comparison of the two methods shows that results obtained from the




regression method for all seven cases are in excellent agreement with




those of the  harmonic analysis for both the mean values and the first




harmonics while the second harmonic values agree quite satisfactorily.





     In all cases, the "computed" (i.e., regression method) diurnal




average temperature is within 0.2°C of the "observed" (i.e., harmonic




analysis) and the root-mean-square-difference (RMSD) is only about 0.1°C.




The computed amplitudes of the first harmonic are all within 7,6% of the




observed, while the RMSD is 4.3% of the observed mean; four of the seven



stations show agreement within 0.06 rad (15 min in time) between computed



and observed phase lags in the first harmonic, while the differences in




the other three range from 0.14 to 0.23 rad (— 35 to 60 min).  Agreement



among the amplitude and phase terms is less consistent in the second



harmonic, although still encouraging.  Five of the amplitude terms agree



within 0.2°C or about 30%, although two differ by up to 0.4°C; similarly,




most phase terms are within 0.4 rad (about 45 min) except two that differ




up to 1 rad.  However, the overall agreement is good as the first harmonic




explains over 95% of the total variance.





     As a result of these tests, the regression method was applied for



the analysis of the effective surface temperature data obtained from the




aircraft PRT-5 measurements.  To evaluate this application, the seven




                                   56

-------
               PMQ
   -f- Wind
   ^ Temperature and
     Humidity

     Data Used From
     These Sites
                                                                     SA-2322-37
FIGURE 22   NEAR-SURFACE METEOROLOGICAL STATIONS OPERATED BY ILLINOIS STATE
            WATER SURVEY, AUGUST 1972
                                      57

-------
















r-H
03
EH
































iz;
o
M
co
co
W
PS
O
w
OS
g
M
o

oo

o
1-H
^
g
1

I-H
o

_H
CO
rj

K
EH
O
O
OMPARIS
0





















EH


W

H
2
W


H
W
M
@
*jj
"^
0
1
co
1
os
s
jz;
r ,

K
EH
PH
O
w
ANALYS
























^
w
OS
co
r-H
| — 1
3

EH
to
rl
EH
S5
OS
O
w
19
^
r-H
CM
t>
, — |


H
CO
B
cn
§




















•o
03
* JH
CM O
« r-H
CM
u
o
EH l>
CM tD
- - o-
M
* . !
£ * ^
< coM §
§
•H
(/I
tfl ^~
0 0
£ EH CO
0? O

y
o
CO
lEH
cn
rH


•o
03
•£ £-*
CM 00
> TD
r-H 03
rt * . r,
fi ^ CO
< -0 rH
O ^
•H
rl C_J
g EH CO
S <^ "
W m

CJ
O
lEH tO
cn
H




*
s
0
•H l>
-P to
03 rH
-P
CO
0
Jz;
00
rH
to
0
m
to
CO



0
o
to



rH
rH




O
m
o


oo
00
o




o
cn
CO
CM
CM
to



CM
fj
rH







O
00
rH

•
O
!z;
00
1— 1
CM
rH
rH
cn
r-H
^'



to
0



to
t>
rH




m
rH


0
to
O




CO
CO
^F
m



i>
r-,'
H






O
O
r-H

0)
-P
03
^
CO
rH
to
0
o
m
••*



00
CO



CO
o
CM




co
CO
rH


H
[•*-
O




CD
•*
CD
to
CO




to




t>
o
rH


^
GO
0




00
CO
cn
to



to
to
i-H







l>
rH
O

•
O

GO
CD
rH
O
GO
O
O
CO

00



oo
cn
H








CM
m



m
co
H










C Q
03 CO
OJ g
S OS























CM
CM

QJ
3
be
•H
PM
C
0
C
0
ai
QJ
JH
03
to
£
O
•H
03
0
o
rH

C
O
•H
-P
03
-p
co
•&
58

-------
space-averaged temperatures obtained from the upper altitude for site


R-l were analyzed first ; the resulting five-parameter fit is illustrated


in Figure 23.  The fitted curve looks quite reasonable for the daytime


period, but the nighttime portion is unrepresentative in comparison


with the shape of the near-surface ambient temperature curves for the


seven ISWS stations; the fitted ambient temperature curve for station


number 022 is also shown in the figure.  The discrepancy undoubtedly


resulted from the large time interval between the last evening datum


and the first morning value.  The importance of one or more measurements


during this period was anticipated, but as noted earlier we were unable


to obtain these due to mechanical failure of the aircraft.  In lieu of


an intermediate measurement, we estimated a reasonable value in order


to inhibit dominance of the nighttime regime by the second harmonic, as


illustrated in Figure 23.  The interpolation is necessarily subjective,


although consistent among sites:  a value (Tj^) is obtained midway


between the 2000 and 0400 CDT measurements by assuming that 60% of the


surface cooling occurs during the first half of the interval.  This


rate reflects nighttime surface cooling typical of cloud-free conditions


as experienced during the experimental period.  The temperature change


over this interval ranged on the order of 10°C at the nine sites.  It


is felt that the magnitude of the uncertainty of the interpolated value


is on the order of 1°C .   An error analysis was then made to evaluate


the impact of the upper level PRT-5 data for site R-l and to vary the


magnitude of the interpolated value over 0.5°C increments through ±2°C.


The rate of change with temperature in each of the parameters of the


regression analysis was essentially constant, where



                             AT
                             —    = 0.20,
                             AT
                               INT
                                   = - 0.22,
                                  59

-------
  30  —
          »                     V
          \     AIRCRAFT, PRT-5  /
                SITE R-1
   0

   0000
        1200

CENTRAL DAYLIGHT TIME
FIGURE 23   COMPARISON OF TWO-HARMONIC TEMPERATURE WAVE AT STATION 022

            AND TWO-HARMONIC REGRESSION ANALYSIS FOR  SITE R-1 USING  SEVEN

            DATA  POINTS
                                     60

-------
                         AT
                           INT
                               =0.03 rad/°C,
                                             '
                        A[A T]

                        	 = 0.26.
                        AT            '
                          INT
                         A5 *
                           —  = - 0.04 rad/°C.
                         ATINT



In view of relatively small impact of "errors" as large as 1°C we feel


confident in the representativeness of the regression analysis employing


the single interpolated value.  Certainly the resultant diurnal curve is


more consistent with both the near-surface ambient conditions and what


one would expect on the basis of the meteorological state.  Figure 24


illustrates the five-parameter (two-harmonic) fit for the PRT-5 data at


each of the two levels for the nine surface sites; Table 6 in the next


section lists the mean, amplitude and phase values.



C.   Application and Results



     In view of the available experimental data and the basic objective


of the study to evaluate effective surface geophysical features, the


specific aim of the analysis program was to determine the feasibility


of obtaining the thermal (i.e., thermal admittance) and evaporative


(inverse Bowen ratio) descriptors of a variety of land-use types through


the application of climatonomic theory to direct and remote observations.


The first step in the analysis is the procedure to specify the solar


forcing function at each of the sites and then the primary response


function (i.e., surface temperature); through parameterization, the


secondary responses are specified or evaluated, and then the descriptors


are determined.
                                  61

-------

30
J
25


J 20
'
D
( 15
•
j
; 10
]

5

30

> 25
20
J
5
	 1 | 	 1 	 1 	 1 	 1 	 [ 	 1 	 1 	 1 	 1 	
SITE: R1 , * .
ALT: 1220 m *
— 9. —
-

— .' •,• -

— ^' ~
~Y
~ \ •' ~
''•- •


•
i i : | i

i ; i ! i
- SITE: R2
_ ALT: 1220 m . *


•' "'--.
c 15 :

j
; 10 - ''-..•
] ' -.
l~ " •
5
30
j
25

_ -
i i ' i

ill i i
SITE: R3
- ALT: 1220 m . »
oo
30

25
I I I I I I I I II
SITE: R1 . * ,.
ALT: 460 m ,.
^
- / '\ -
)— A'' '\ —

20

- . ' Q —

« E. / " - J
(_ '-, ,' _-
10

- '''--. • .-•''

- 9 ~
5 -

35

30
25

20

I ' I '

I I I I I 'I
- SITE: R2
- ALT: 460 m , *
V
-
,' \ — I
7 > J
I
15 h. / "-->
r""'-- •'' -\
r '•• .•' i
10 I- •-.• ..- -\

30
r- "' -I
III I i

I'll
SITE: R3 . •
- ALT: 460 m ±
X \ 1 25 ^ / > -j
1- / -. ~\ I
S2°C J . 1 »r 1 "\ J
r- '
t 15 - / '-•-.. -I •'' '••-..
E-, / "^
L ^ '-.
> 10 r --.•
- r •
5 h
I i i i i . i
15


10

R
~. •' ""•

'•-. u
*•--.-••'
-
i i i i i i i
   0000     0600     1200      1800
                 CDT 	 hours
2400   0000     0600     1200     1800     2400
                    CDT — hours
                                  SA-2322-10A
FIGURE 24    EFFECTIVE  SURFACE RADIATIVE TEMPERATURE FROM  TWO  AIRCRAFT
              ALTITUDES  AT NINE SITES ON  9 AUGUST 1972
              Curve is from 2-harmonic regression analysis
                                        62

-------
  35
OD
0 30
I
1 25
LU
f£
D 20
1-
Ot 15
LU
Q-
S 10
H

5

! I i I III I
SITE: R4
ALT: 1220 m
v

\

-
*
*' '••-..

— ,'
'••»_

•

ill I , I '
40
35

30


25

20


15

10

C.
SITE: R4 *.
- ALT: 460 m
'•
•'•
/

-
•/
•^


'-••-.. /'' '"•----<
~ • »
--..--•'
*
i i ' i i i
	 	 u ~
35
o
1 30
I
1
LU 25
DC
j- 20
e3-
01
LU
o- 15
LU
•- 10

35
o
° 30

I
LU 25
DC
D
1- 20
<£
CL
£ 15

LU
1- 10
5
i ' : i i i i T
SITE: R5 »
ALT: 1220 m
4 ••


' .

* ~ .



•*
i . . , '

I
SITE: R6 ^
~ ALT- 1220 m
* '•


.

•


•

.
"----;
i . i i i i i

40
35
30

25

20


15
10

40
35

30

25


20


15

10
5
. SITE: R5 . ^
ALT: 460 m
_
;

• «



'" '
"'•*--;'
i ' ' iii

i i i i iii' i
SITE: R6
ALT: 460 m
—
*
_


>
,

4

— ''-•/'
''---i
II II' 111

0000 0600 1200 1800 2400 0000 0600 1200 1800 240
                CDT — hours
                                                        CDT — hours
                                                                      SA-2322-10B
FIGURE  24   EFFECTIVE  SURFACE RADIATIVE TEMPERATURE FROM TWO AIRCRAFT
             ALTITUDES  AT NINE SITES ON 9 AUGUST 1972
             Curve is from 2-harmomc regression analysis  (Continued)
                                      63

-------

30
}
25

J 20
5

t 15
j


j
5



J 20


I 15
>
c

J
: 10
«
J

5
25
j

20

LJ
C
D
- 15
C
J
L
S 10
B
I I I I I I I I I I I
SITE: R7
ALT: 1220 m
• '••
'*•
/
• 'X.

''--.-
i.. / •

'\ •
'--....-•'
-
i i i i i i i i i i i

i i i i i i i i i i i
- SITE: R8 , • .
_ ALT: 1220 m £ V
'•-•
• /
-
\ 1 '


- \
- ''-. * /' I
'"---'
1 i i i i i i i i i i

i i i i i i i i i i i
I SITE: R9 .- -V -
~ ALT: 1220 m
/• V -
-
I •,•'' > I
- /' _
—
" >_
/ 4

: ''''••-• ../ :
~ i i i i i i i i i i i ~
OQ
30

25

20


15


10

5

25


20

15



10

5

25


20


15



10
R
I 	 1 	 1 	 1 	 ! 	 1 	 1 	 1 	 1 	 1 	 1 	
SITE: R7 • i
ALT: 460 m /
''••
-
•''
-

-

•' •
~'\ / ~
- ''•-. • /
""""'
i ;ii

i I II
- SITE: R8
ALT: 460 m * .
\»
-
7 '•-•
'' •-. -




''--. * ••''
iii

iii i i i i i i ii
SITE. R9 ,-*-.
- ALT. 460 m . ,

/' *
-

'•-.. -

_ / 4

'•-.*
I I I I 1 1 I I I I I
   0000     0600      1200     1800    2400  0000
                 CDT — hours
0600      1200      1800     2400
     CDT — hours
                   SA-2322-10C
FIGURE 24   EFFECTIVE SURFACE  RADIATIVE TEMPERATURE FROM TWO AIRCRAFT
             ALTITUDES AT NINE SITES ON 9 AUGUST  1972
             Curve is from 2-harmonic regression analysis  (Concluded)
                                       64

-------
     Table 3 listed the mean, amplitude, and phase terms for the


insolation on 9 August.  The surface reflectivity then determines the


form of the forcing function at each site.  Table 5 lists the albedo


values observed at each site for all of the daytime flights on 9 August.


In Table 6, the albedo and forcing function are summarized according


to site and aircraft altitude; for convenience, the downwelling longwave


flux given earler in Table 2 is also summarized in Table 6.



     The diurnal surface temperature variations discussed earlier and


illustrated in Figure 24 are the effective surface radiative temperature


values deduced from the aircraft bolometer  measurements and an assumed


constant surface emissivity of unity.  To obtain some insight  into the


magnitude of possible variations in surface emissivity (e), we evaluated


relative e-variations among the nine sites by assuming that the actual


mean surface temperature was indeed the same for all sites.  Thus


differences in the effective mean surface temperatures are essentially


attributable to variations in the emissivity.  Using the upper level


measurements first, it was found that the relative e-variations are on


the order of 7%;  the largest e-values are associated with the more


urbanized sites.  The lower level data resulted in similar findings with


relative e-variations less than 9%.  The possible error introduced by


assuming s = 1 in the climatonomic determination of F  and A T  (and
                                                     i      i o

subsequently,  the other second order responses) is minimal; thus, for


the lack of an objective determination of absolute emissivity at the


various sites, the unity value has been used throughout.  The mean,


amplitude, and phase terms for the primary response function (TQ) and


the upwelling longwave flux (LWot) are summarized in Table 6.



     As discussed earlier, the B_  and (3 _  terms describing the downwelling


longwave flux are derived from the harmonic analysis of the pyrgeometer


measurements at the surface station.   These values have been taken as


representative of conditions at all nine surface test areas.


                                  65

-------
in

0)
rH
42
OJ
EH
   03
   OS
CO
H  PS

«S
os  t*
S   01
   rH
CO  EH
h*^


9

0*3
OS

°P
OS

1
OS

T
1 *
§, "i5
•P
•H
W 1

°?
OS

?
OS

rH
1
OS


"7
o
f-i
ft
ft
cd
•P ^-^
bo 0)
•H S
H -H
PTJ C^
m
CO
H
•*
CD
H
01
Tf
H
rH
CO
01
rH

m
CO
rH
CO
rH
oo
co
H
co
CD
rH
£
o
CM


• •
0
T) EH

•P O
•H O
-P O
H en
<; o
CO
CD
rH
CM
CD
rH
O
in
rH
0)
CM
m
CM

o
^
00
CD
H
CD
CD
i-H
C5
m
rH









o
CO
H
H
CD
CD
r-H
CM
CO
H
CM
in
rH
CD
CM
Ol
H

CO
co
CD
in
i-H
m
in
rH
CM
m
rH









o
co
CO
H
t>
CD
rH
O
O!
rH
m
t>
i-H
rH
m
co
co

co
^
^
CD
rH
CD
m
rH
CO
m
rH









O
0
CD
rH
<*
m
rH
co
CO
rH
^
<*
rH
TP
co
rH

rH
CM

H
CD
H
Ol
t>
i-H
oo
CO
i-H









O
0
CT5
rH
<#
CD
rH
Ol
CD
rH
<*
m
rH
CO
CO
CD
CM

O)
co
CM
CD
H
in
co
rH
<*
m
rH







CU
bD
a
0)
^
•a;


























e
o
^

• •
cu
•o
3
•P
•H
•P
H
ejj
01
^
rH
CM
CD
H
H
in
H
01
rH
O
CM

00
CO
rH
CO
CD
l-H
CM
CD
rH
05
in
rH







c_i
/""I
8
O
05
O
o
CD
rH
00
CO
rH
in
^f
i-H
0
(M
CO
i-H

00
co
rH
o
co
i-H
m
m
rH
T-H
m
rH









O
co
H
rH
m
CD
rH
00
CD
i-H
co
t1
rH
O
CXI
H
CM

•*
CO
rH
CD
i-H
CO
[^
H
oo
•^
rH









O
CO
CO
H
CD CM
CD CO
rH rH
co m
CD CD
rH rH
Ol t>
•^ ^
rH H
in I-H
CM CM
H4
rn
rH CM
CO CXI

co oo
•* co
rH rH
•* CD
l> CO
rH H
CO CD
O CD
r-H H
N ^
in in
H rH







CD
bl
03
O rH
O CU
CD >
rH 
-------
to

01
rH
a
                         *
                         rl
                        8s
                      o  5
                         B
                         T3
                      rl  «
                    10    rl
                         C
                      O  -H
                    *    S
                   I fa
                         B
                         TH
                      O  S
CM CM
O 0
CM r-
to in
0 0
Cn rH
t*. 00
in ^
CM r~
to <0
CO V
cn in
in in
S S
? °
00 CM
in to
CO CO
o o
0 0
m «•
cn o
CM 00
gs s
in in
m in
in in
o o
m cn
rH H
o o
en cn
CM CM
CO CO
t- r-
m m
o o
CM CM
to to
CO CO
o o
3 J
rH rH
a a
CM
o
in
"
o
cn
t-
rH
CM
t-
O
»
to
CM
CM
O
1
rH
to
N
cn
o
cn
cn
"
00
cn
00
CM
m
m
in
o
cn
rH
0
S
CO
O
m
o
CO
o
o
04
X
rH
O
in
to
o
rH
00
N
00
CM
in
rH
O
CM
to
CO
00
0
CO
cn
CO
rH
in
m
o
(0
cn
rH
o
cn
CM
CO
o
o
f-
m
CO
o
J
N
tf
co to
rH rH
O O
co oo
t* (0
0 O
en o
t- CO
CM rH
in r-
to in
CM cn
in CM
to to
0 0
o o
1
CO CO
CO CO
co to
0 0
to to
CM t-
00 00
00 CO
cn I-H
oo cn
CM CM
in m
in in
in in
o o
r> to
cn en
rH rH
0 0
8S
CO CO
CM O
m m
0 0
00 C*
in in
CO CO
o o
0 rH
CO CO
CM
O
N
to
o
o
00
(0
t-
cn
rH
(0
rH
CM
O
cn
rH
•*
rH
O
§
O>
0
rH
m
m
o
1
o
s
CO
r-
in
in
0
cn
to
CO
0
S
K
CO
rH
O
G>
V
O
CO
CO
rH
cn
CO
CM
3
•3"
O
to
en
*
00
o
to
N
iH
m
I
in
in
in
o
CO
o
en
CM
CO
in
in
o
cn
to
CO
0
J
a
rH
CM
O
to
m
o
CM
00
O
f
in
c-
CM
in
in
o
o
o
00
CO
rH
0
in
to
0
rH
O
CO
m
in
in
0
8
o
8
CO
in
to
m
o
Tl*
CO
o
p
in
cn
00
rH
O
,
^
o
CO
00
cn
5
cn
in
cS
0
en
•*
00
o
s
CM
rH
01
s
in
in
in
o
1
o
s
CO
00
to
in
o
to
CO
0
j
in
a:
rH rH
O 0
00 rH
m in
o o
CM V
00 00
X r-
cn x
T CO
t- •»
CM 'J1
in ^r
82
c> o
1
x to
CO ^
t* in
o o
o x
fll 00
O rH
rH rH
CM tO
co in
cn cn
CM CM
in in
in in
m in
0 0
§ §
CM CM
O O
en cn
CM CM
CO CO
rH CO
to to
in in
o o
rH tO
t- t~
CO CO
0 0
S r3
to to
ce a:
^1 00
rH O
O 0
oo to
to m
o o
O> rH
t^ 00
^ 
CM &
m in
m in
in 10
O O
cn o
cn o
rH CN
O O
cn 01
CM CM
CO CO
b- W
in in
o o
N m
to co
CO CO
o o
Z> rJ
tt tX
r» rH
o o
t- 00
00 f»
O O
00 00
> t*
m to
CO 0)
H cn
rH
CO 
SS
in N
^ m
? ?
N O
tn rH
H CM
I> rH
O O
§ 5
0) t-
co cn
00 X
00 X
CM CM
in in
in in
m in
0 0
10 to
a> cn
rH rH
O O
en cn
CM CM
CO CO
CO O
CO ^3*
in m
0 O
to t*
in in
CO CO
0 0
a rH1
X CO
K, K
CM 1»
CM CM
O O
tD rH
X X
O O
x cn
r- r-
X 1>
to m
O CM
r-t
10 i-t
S S
S3
O O
1 1
ss
rH rH
CM f-
m in
o o
§x
n
t- r-
m H
Sen
x
CM CM
in in
in in
in in
0 0
t- t-
cn cn
rH I-H
O O
en en
CM CM
CO CO
CM CM
•a1 -a1
in in
o o
x x
in m
CO CO
0 0
p .J
cn cn
ce K
                                                                                                                             B

                                                                                                                            8
                                                                                                                             rl

                                                                                                                             &
                                                                                                                             a
                                                                                                                             3
                                                                 67

-------
13
•o
3
ID


1)
01
cal

s,
*


*"

*H
»
•»-
-
9-™

«."

ff-
S^

««
IV

o

CD.

«



-H
cn

•o
•*s
<^s
f
ft
s.
m
\M"
^-\
5
r-l
s-'
£
^r>*
S
^S
C

fl
>^
^N
**\
I
4^
•w
^N
O
w
/•s
O
*•/
/"»*
Nil/
^•S
^
,a
x
t
N^
0)
!i
2
<
o
rH
CM

ID

O
to
X
I
N
3
S
0
X
CO
o
•*
rH

to
CO
o
^
o
$

in
to
?
m
m


o
rH
ce

*
rH

5

O
> i>
0 0
CD J
X X
o: as

rH i>
in in
CM ,H

CO CO
in t-

to o.
m r-t
m o
f f
rH CO
CM CO
e ?
o o
* *
o o
r-l rH
to to

rH rH
O O
o o
m m
x x
CM CM

§o
0
rH rH
Sin
m
? ?
CD O
O rH


3 J
cn cn
a as

                                             68

-------
     Estimates of the amplitude and phase terms for the atmospheric



flux of sensible heat follow from Eqs. (13) through (15).  The aero-



dynamic surface roughness is computed with Eq. (15a) using characteristic



physical heights estimated from the aerial photographs for the various



sites (see Figs. 13 through 21).  The geostrophic wind was estimated



from the two NWS low-level EMSU soundings (0600 and 1130 CST) to be



about 6.5 m sec  .   After computing the surface Rossby number at each



site, the geostrophic drag coefficient and the surface friction velocity



are determined from Eq. (15).  Terms $ and cp have been tabulated in



Table 6 based on Eq. (14) and the following constant values:  a = b = 8.5;



c = 17,  and M* = 0.2.





     Having parameterized the radiative fluxes and the atmospheric



sensible heat flux, the solutions for both the evaporative and the



subsurface heat fluxes are obtained by using the known amplitude and



phase terms together with Eqs. (8) and (9).  Since i|r and x are known,



both V and X, and subsequently (j, and Bo can be evaluated with Eqs. (12c)



and (16a), respectively.  In the case of the partial impedance for



evaporation the sum of $ and X has been evaluated using Eqs. (8) and (9);



the X-values are then obtained as the residual using the $-values as



discussed above. The thermal admittance p, follows from fusing Eq.



(12c).   The values  for W, Bo, and (j, evaluated in this manner using



first harmonic amplitude and phase terms were summarized in Table 6.





     In summary, we have taken measured radiative parameters and certain



parameterized (synthesized) values and through the application of



climatonomy have determined two important geophysical features of the



sites:   the thermal admittance (|_i) is obtained through consideration



of the submedium at each site as a homogeneous conductor of heat; the



inverse Bowen ratio (Bo) expresses the magnitude of the evaporative heat



flux as a fraction  of the sensible flux of heat to/from the atmosphere



at the  earth/air interface.  Keeping in mind the limitations noted both




                                  69

-------
in the measured and parameterized values, it is possible to subjectively




evaluate the representativeness and significance of the results.  It is



encouraging to note that all sites have p,- and Bo- values that are in



the range of what might be anticipated.  For example, y, ranges from a




minimum of 22 mly sec"-*-/2 °K   in open farm country (R-7) to a maximum




of about 87 at the wooded sites (R-8 and R-9); the mean value for all




sites is 42.  Lettau9  lists typical p-values determined for a variety




of homogeneous media:   soils range from 14 mly sec"1'2 °K   for fine,



dry quartz sand to 47 for the same sand with 22% moisture; y, for "sandy




clay (15% moisture)" is given as 36 while "swamp land (90% moisture)" is




44.  Rocks range from 45 for basalt to 56 for granite and concrete.




Regarding heterogeneous surfaces, Lettau estimates "fields, weedy swamp,



still water, and hilly woods" to have y,-values of 35.  Examining our




results in view of this background, several conclusions may be drawn.



First, the absolute values of the computed thermal admittances are




reasonable.  Second, the highest values occur at sites R-2, R-8, and



R-9.  These three sites share one common feature not typical of any of




the other six sites:  they are all dominated by a high percentage of




wooded areas.  It is interesting, however, that Lettau estimates y, to be




smaller by a factor of 1.5 to 2 for similar terrain, although he does not




state whether his estimate is a summer or winter value.  It is quite



conceivable that the presence or absence of foliage  significantly alters



the effective thermal conductivity of a wooded area  and that the former



situation may lead to larger values of y, as a result of the increased




surface area and concurrent increase in mixing and the transfer of heat




away from the canopy.





     The "developed" sites (R-3, -4, -5, and -6) all have quite similar




values of the thermal admittance, around 25 mly sec~l/2 °K~ .  There does




not seem to be any noticeable difference in y,  among  the various building-




zone types; i.e., new and old residential and commercial all appear






                                  70

-------
 similar.  One possible exception is site R-6, where p, computed from the



 lower level aircraft data seems somewhat low.  No conjecture is offered



 in explanation.





     Site R-7 is a good check on the method as the site is simple,



 homogeneous and extensive, and experience dictates a low value for u,—



 Lettau9 estimates 35.  The two ^-values for this site are 32 and 13,



 averaging out to 23.





     Without supporting surface observations, it is difficult to evaluate



 all of the Bo-values.  Most values are less than 2.5, with site R-7 the



 maximum, having an average Bo of 3.5.  There had been showers in the



 area on 8 August and hence the Bo-values are not unreasonably large.  It



 is significant that the lowest values are found for three of the four



 developed sites, R-4, -5, and -6.  This is to be expected due to the



 increased runoff in urban and suburban areas and the corresponding



 decrease in evaporation.





     A final observation is in order regarding the distribution of u.



 and Bo at the nine sites:  although the theoretical formulation used in



 evaluating the surface energy budget explicitly ignored energy fluxes



 associated with photosynthesis (or anthropogenesis), the impact,



 if any, of such fluxes is reflected in the measured values.  Hence in



 using the climatonic theory in the valuation of p, and Bo as (essentially)



 residuals, we have implicitly accounted for the impact of such other



fluxes in the determination of these parameters.  Thus, for example, it



 is not unlikely that the large Bo-values determined for the undeveloped



 sites relects some impact of photosynthesis.  This may in part explain



why the largest Bo-values were found for the agricultural site.





     The |j,- and Bo-values tabulated in Table 6 are the result of the



 analysis of the first-harmonic data.   Since ^ and Bo are frequency-



 independent, all harmonics should yield similar results.  Difficulties





                                  71

-------
were encountered in attempting to evaluate both parameters on the basis


of the second-harmonic data:  y,-values became negative, while Bo was


excessively large in many cases (up to 25).  There are three possible


explanations for these discrepancies:  (1) errors in the regression


analysis used to infer the amplitude and phase terms from the surface


temperature data, (2) experimental inaccuracies such as instrument


drift or (more likely) wander of the flight track, and (3) limitations


in the theory—particularly in the neglect of photosynthetic and


anthropogenic fluxes.  Most likely, each contributes to the problem.  On


the assumption that the cause lay in the data and particularly in the


determination of the second-harmonic terms, a simple feedback analysis


was pursued wherein effective AT- and 6 -values were derived that
                               2t O       £

forced the determination of u.- and Bo-values equal to the first-harmonic


results.  In 16 of the 18 cases, the "effective" temperature amplitude


(A2T0) differed from the original (Table 6) by less than 0.7°C; phase


differences were generally larger, averaging about 0.6 rad or 70 min.


Differences in both terms are certainly within the range of possible


errors associated with the regression method for determining Fourier


coefficients (see Section V-B) and/or with departures from the aircraft


flight track (leading to differences in scene at the nine sites from


flight to flight).



     Table 7 then summarizes the amplitudes of the atmospheric sensible


and latent heat flux densities and the subsurface heat flux density on


the basis of (1) the first-harmonic (j,- and Bo-values, as derived above,


and (2) the temperature amplitudes (A^TO) determined earlier from the


regression approach.  To illustrate the diurnal fluctuations of these


fluxes and their variations among land-use types, Figure 25 illustrates


these differences for three sites:  farmland (R-7), commercial/industrial


(R-4), and new suburban residential (R-3) .  The curves have been derived


from Eqs. (2d through f) using averaged amplitude terms from Table  7 and


phase terms from Table 6.


                                  72

-------
                              Table  7
     DERIVED AMPLITUDE TERMS FOR ATMOSPHERIC SENSIBLE  (AiQo),

     LATENT (AiE0), AND SUBSURFACE  (AiSo) HEAT FLUX DENSITIES

                          Units:  mly/min
Site:
Altitude*
R1:U
R1:L
R2:U
R2:L
R3:U
R3:L
R4LU
R3:L
R5:U
R5:L
R6:U
R6:L
R7:U
R7:L
R8:U
R8:L
R9:U
R9:L
A Q
1 0
103
112
106
122
124
131
155
211
183
212
179
204
87
107
91
101
105
111
A2Qo
36
34
38
57
49
55
79
96
70
85
76
99
37
36
24
28
33
25
A E
1 0
217
194
125
251
364
298
229
165
178
170
250
235
319
352
33
254
264
174
A E
2 o
76
59
45
117
143
125
116
75
68
68
106
114
135
120
9
70
82
40
AS
1 0
229
235
325
166
55
109
174
156
194
159
119
101
144
73
435
199
190
275
2 o
107
94
157
103
28
60
116
93
98
84
66
64
81
33
154
72
80
83
*
   U = upper (1220 m mgl)


   L = lower (460 m mgl)
                                 73

-------
        400
                           10       15
                        LOCAL TIME — hours
20       25

  SA-2322-39
FIGURE 25   DIURNAL. VARIATION  OF DERIVED DEPARTURES
            (FROM DAILY AVERAGE) OF ATMOSPHERIC,
            LATENT, AND SUBSURFACE HEAT FLUX DENSITIES
            FOR THREE  LAND-USE TYPES:   FARMLAND (	),
            COMMERCIAL/INDUSTRIAL (	), AND SUBURBAN
            RESIDENTIAL (	)
                           74

-------
                  VI  CONCLUSIONS AND RECOMMENDATIONS








     All of the data collected during the experimental programs in St.



Louis have not been fully exploited for information content.  Additional



analyses would include not only the aircraft observations but also a



variety of surface observations collected during the same period under



other observation programs.  Detailed photographic analysis was limited



by the scope of the present study.  Nevertheless, the program demon-



strated the feasibility of acquiring observations of the time changes



in the solar forcing function and the primary response function (surface



temperature) and for inferring, in conjunction with climatonomic theory,



secondary responses as a function of surface type.  In this way variations



in the surface energy budget are described.  Magnitudes and variations



in both observed and derived quantities were established by the program,



and a useful evaluation of program requirements for future applications



is now possible.





     Considerable rechecking of both observational and theoretical results



with independent data is of course, desirable.  Improvements in data



acquisition and processing techniques would be introduced as a result of



past experience.  Although it is easy to expand an observational program,



certain improvements must be given priority.  From the aircraft platform,



measurements of reflected solar radiation and surface infrared emission



should be obtained with the same field of view, and over a complete 24-



hour period (with overlap).  Furthermore, solar radiation measurements



(in both directions) should be expanded so as to permit a separation of



visible and near-infrared contributions.





     The program for the analysis of other standard aircraft data could



be expanded considerably with a good payoff to a study of the type




                                  75

-------
conducted.  Because of the importance of small changes in the surface



albedo and surface temperature, more effort is required to assess the




magnitude of the atmospheric influence on these measurements (by virtue




of observed changes with altitude).   A more careful analysis of the air




temperature data collected at each of the two flight altitudes provides




information on changes in stability and advection within the boundary




layer; corrections for cooling or heating during each traverse can be




accomplished with the observations themselves.  In addition, harmonic



analyses of the aircraft-measured temperature in the boundary layer over




each site of interest would assist in the analyses of the secondary




response terms in the climatonomical analysis of the surface energy



budget.  Finally, inasmuch as ground-speed determinations between check




points are documented, wind estimates at two altitudes along the flight




track could be obtained fron the indicated air speed, ambient temperatue,




and drift angle.  Because of the need for a more careful representation




of flow conditions, this wind information should be supplemented with




additional surface wind observations at locations along the track and




with at least four balloon soundings per day at one location.  Together




these data would provide a more detailed assessment of the temporal and




spatial variations  in the atmospheric flux of sensible heat.





     Surface radiation observations (along with temperature, humidity,



and wind) should be expanded to cover several preselected sites of




different types along the flight track.  Better descriptions of surface



structure with improved input information on roughness and potential




evapotranspiration are required.  Inventories also are required on




photosynthetic and anthropogenic heat sources, both of which have been



neglected thus far.





     Lastly, several important improvements need to be made in the




aircraft operations.  First, more frequent flights over a 24-hour period



need to be made:  on the order of 10 to 12.  This is necessary to over-





                                  76

-------
come potential difficulties in the determination of Fourier coefficients.



Secondly, more active control of the aircraft flight path needs to be



implemented to assure repeated overflights of the identical surface scene.





     The results to date are encouraging:  the study has demonstrated the



feasibility of this method for evaluating the structure of the surface



energy budget.  Incorporating experiences and the recommendations herein,



we recommend the program be expanded to evaluate in a systematic fashion



the geophysical surface features of a broad range of typical land-use types



under varying meteorological conditions.  In this way we will be able to



look at such interactions as the impact of soil moisture on thermal



admittance, foilage and its effect on albedo, and so forth.
                                  77

-------
     Appendix A





AIRCRAFT DATA SUMMARY

-------
                              Appendix A

                         AIRCRAFT DATA SUMMARY

     Most of the aircraft measurements of solar radiation, surface
temperature, and air temperature are  summarized graphically in this
appendix (Figures A-l through A-14).*  All data are plotted as a function
of flight track range.  The origin of the range for August 1972 data
coincides with the northernmost checkpoint of the August 1972 flight
track shown in Figure 2 of the text;  the range for April 1973 data
originates at the westernmost checkpoint shown in Figure 2.  These origins
are maintained regardless of the direction of motion of the aircraft at

either of the two flight altitudes.  The major urban area for August
flights falls between about 33 and 45 km range while the major rural
areas occur over the last two-fifths  of the track.  Along the April flight
track the urban area is more varied;  the major portion of the urban areas
occur between about 26 and 47 km range while the major rural areas occur

over the last third of each flight track.

     Solar data are presented for the August flights only.  The characteristic
dip in the albedo traces near the origin results from crossing a broad
section of the Mississippi River (see Figure A-l); a broad dip in the
albedo curves occurs over the urban area.  Irregularities in the measured
downwelling solar irradiance (solid curve) are produced by clouds above the
aircraft and are frequently associated with irregularities in the albedo
curves as well,  especially when the aircraft pyranometer is shaded but the
surface directly beneath the aircraft is not shaded.  Variations in incident
solar radiation with changes in solar zenith angle also are revealed by
time changes in the solid curves.  Especially characteristic of convective
activity are the data for the 1630 CDT flight on 11 August 1972 (Figure A-9);
*For convenience,  the illustrations for this appendix are grouped after
this discussion.

                                 A-3

-------
showers forced cessation of the observational  sequence at  this  time.





     The sequence of radiometric surface temperatures for  9 August  1972




(Figure A-10) clearly shows the pronounced increase in surface  temperature




variability associated with daytime solar heating.   At night the surface




temperatures are relatively uniform except for water bodies (rivers),



which appear as pronounced warm spikes.   These spikes provide an



excellent nighttime check on the actual  flight track.  The low-level




flights of 0400 and 0630 CDT actually strayed  too far to the east as




evidenced by the double spikes appearing between 25 and 31 km range;



these correspond to two crossings of a bend in a Mississippi River




channel along the northeastern border of St. Louis  (cf., Figure  2).  As




the land areas heat to their maximum temperatures,  the water bodies



appear as minima on the temperature curves.





     Figure A-ll portrays graphically the air  temperature  as a  function



of range at both altitudes; a comparison of the traces provides an




immediate indication of stability (above  460  m) .  These records are




sensitive to slight changes in aircraft  altitude; unfortunately, a precise




altitude record was not available for the data.  If it is  assumed that the



data have been properly calibrated and that the aircraft altitude was



essentially uniform along each leg, then it appears that at the start of



the period cold air advection (with northerly  flow) was still occurring,



with greater stability between 460 m and 1220  m over the rural  area along




the southern portion of the track (beyond 50 km range).  By afternoon the




temperatures have become more uniform and the  stability has decreased.





     Data in Figure A-12 for 11 August 1972 are similar to those in




Figure A-10 for 9 August 1972.  In Figure A-13 (11 August 1972), the




air temperature data conte.in many noise spikes; these spikes should be



ignored.  Nighttime data for 11 August suggest less stability beyond




50 km range in contrast to the observations of 9 August.  Of course,  from
                                 A-4

-------
the surface temperature measurements it is also clear that the same



region has much greater stability below the 460 m altitude.  Nevertheless,



the trend of the airborne air temperature data is disturbing, showing



an increase with flight time (460 m flown first on this flight sequence).



Therefore, a firm picture of the air temperature fields in the early morning



periods cannot be established without more observations supplying accurate



calibrations and a careful check on flight altitudes.





     The surface temperature measurements from the April 1973 flights



(Figure A-14) shows the extensive flooded area around the Mississippi



River near the origin of the flight track.  This region is relatively



cool during the 1700 CST flight but, as the land cools, appears relatively



warm in the early morning hours.  The large dip in the dashed trace at



0130 CST should be ignored (10°C not added).
                                A-5

-------
£  2.0
'£
   1.0
01
IT
   0.5
                             DOWN
                               UP
                                                         ALBEDO
                   20            40           60
                                   RANGE  — km
                       (a)  FLIGHT  ALTITUDE 1220 METERS
                                                            80
17.5

15.0

12.5
                                                                         100
 I  2'°
 u
 g  1.5
LLI
0
IT
DC
   1.0
   0.5
             I /
             I I
                                                         ALBEDO -
                               DOWN
                                UP

                                  I
                   20            40            60
                                  RANGE —  km

                        (b)  FLIGHT ALTITUDE  460 METERS
                                                            80
17.5

15.0

12.5
                                                                         100
                                                                      SA-2322-24
     FIGURE A-1    AIRCRAFT SOLAR MEASUREMENTS, 0930 CDT FLIGHT,
                    9 AUGUST 1972
                                      A-6

-------
   1.5
LU
O  1.0
CC
E  0.5
                    DOWN
                     UP
                                                    ALBEDO
                  20           40           60
                                 RANGE — km

                        (a)  FLIGHT  ALTITUDE 1220 METERS
                                                          80
17.5

15.0

12.5
                                                                      100



2.0


3 1.5
S
J
) 1 .0
>
c
5
c
: 0.5
0
I ' I ' I ' I
— _
% ~» »'*»'"x*x
,-v /' *"*\ «% ,''' *
', /' '' '\ ,' '.'' ALBEDO 	 ~-
\ '
^ .\.'
* '
DOWN
~ A /^ "
'. -

UP
I , I . I . I

17.5

15.0
12.5







                  20           40           60
                                 RANGE — km

                        (b)  FLIGHT ALTITUDE 460 METERS
                                                         80
                                                                      100
                                                                  SA-2322-25
     FIGURE A-2    AIRCRAFT SOLAR  MEASUREMENTS,  1145 CDT  FLIGHT,
                    9  AUGUST 1972
                                     A-7

-------
 c 2.0
 E
1  1-0
DC
o:
   0.5
                                                       ALBEDO-
                            DOWN
                              UP
                                  I
  I
                    20
                                 40
 60
km
                                  RANGE

                           FLIGHT ALTITUDE  1220 METERS
                                                            80
                               17.5

                               15.0

                               12.5
                                                                         100
'c 2.0
 E
CN
\
 CJ
IS 1-5
   10
 (E
 DC
   0.5
                                                        ALBEDO
                              UP
                                  I
                    20
                                 40
                                              60
                                                            80
                                  RANGE —  km

                        (b)  FLIGHT ALTITUDE  460 METERS
                               17.5

                               15.0

                               12.5
                                                                          100
                                                                      SA-2322-26
     FIGURE  A-3   AIRCRAFT SOLAR  MEASUREMENTS, 1400 CDT  FLIGHT,
                    9 AUGUST 1972
                                      A-8

-------
 E 2.0
 E
 1
 tr
 oc
   0.5
                                                       ALBEDO
                            DOWN
                             UP
                   20            40            60
                                  RANGE — km
                        (a) FLIGHT ALTITUDE 1220 METERS
80
                17.5

                150

                12.5
                                                                         100
I  2.0
LU
o
cc
DC
   1.0
   0.5
                         DOWN
                           UP
                                                       ALBEDO
                   20           40            60
                                  RANGE — km

                       (b)  FLIGHT ALTITUDE 460 METERS
                                                           80
                17.5

                15.0

                12.5
                                                                        100
                                                                     SA-2322-27
    FIGURE  A-4   AIRCRAFT SOLAR MEASUREMENTS,  1630 CDT FLIGHT,
                   9 AUGUST 1972
                                    A-9

-------






'c 2.0
E
CM
'E
u
"5 1.5
u
LU
0
2 1.0
5

EC
cc
0.5

0
I • I • I • I
-
' • .,----» ••>
• •» ," • »
• \ • »
•» ' ». » • %» . /

_ *»' *••••«''».• ALBEDO 	 — _

,


— —

'

— —

DOWN
^^\ __ ^ ^^ ^^ -
- -
UP
	 . 	 ( . 	 T_,.__ 	 j ^ ^ _

17.5


15.0

12.5















             20          40          60
                           RANGE — km

                  FLIGHT ALTITUDE 1220 METERS
                                                  80
                                                              100
                                                           SA-2322-28
FIGURE  A-5   AIRCRAFT SOLAR MEASUREMENTS, 1915 CDT  FLIGHT,
             9 AUGUST 1972
                             A-10

-------
c  2.0

E
   1.5
m
o

-------
  2.0
  SI C
  I ,
-------






I 2.0



j
5 1.5
J
J
I i-o
5
•
.
c
-
0.5

n
1 ' 1 ' 1 ' 1
_ — -
•- .
\ , ' "-», /•> / » 	 ' \ ,'
- 1 ,*»-- « , --x .'
' . » /-. /
» . » . * t AI nrnn mi
* • \ 1
— * 1 V I 	
\ •-».'•'
\'
• ~
DOWN —

i — —

-

— —
UP
1 . 1 . 1 . 1 .

17.5

15.0


12.5












                   20            40           60
                                 RANGE — km

                       la) FLIGHT ALTITUDE 460 METERS
                                                          80
                                                                       100
.£  2.0
5  1-5
LU
O
   1.0
IT
IT
   0.5
                          'DOWN
                            UP
                                                     ALBEDO
                  20           40           60
                                 RANGE — km

                     (b)  FLIGHT  ALTITUDE 1220 METERS
                                                          80
17.5

15.0

12.5
                                                                      100
                                                                   SA-2322-31
   FIGURE  A-8   AIRCRAFT SOLAR MEASUREMENTS,  1400 CDT  FLIGHT,
                  11 AUGUST 1973
                                   A-13

-------
'c 2.0

 E


CM
I


 U
 UJ
 CJ

 5 1.0
 DC
 DC
   0.5
                                      II
                                      I >
                                      I >
          UP


•i	:'"~"\"
                                              I
                   20
                                40
                                              60

                                            km
                                    ALBEDO
                                  RANGE



                      (a)  FLIGHT ALTITUDE  460 METERS
                                                           80
                                                       17.5



                                                       15.0



                                                       12.5
                                                                        100
 5 2.0
   1.5
 UJ
 o

 < 1.0
 DC

 DC
   0.5
                                                    \   ALBEDO
            * .» '«
             V I ,/ ,
                ' >   " ,«    'i
                 >   '  •'«    11
                 » '    t    i  t
                             UP
                               —r
                            i

                   20            40            60


                                  RANGE — km


                       (b)  FLIGHT ALTITUDE 1220 METERS
                                                           80
                                                       17.5



                                                       15.0




                                                       12.5
                                                                        100
                                                                    SA-2322-32
    FIGURE A-9    AIRCRAFT SOLAR MEASUREMENTS, 1630  CDT  FLIGHT,

                   11  AUGUST  1973
                                    A-14

-------
      50
      40
      30
      20
      10
      30
    I   20

    uj
    DC
    D



    DC 10
    UJ
    a.
    5
    UJ


    in 30


    OC
    a.
      20
      10
                                        I     'I

                                            (d) 1145 CDT
              '
      30 -
      20 -
      10 -
                                            (c)  0930 CDT
               (b)  0630 CDT
                                            (al 0400 CDT
        10
                   20
40        60

RANGE — km
                                                 80        100



                                                   SA-2322-33A
FIGURE A-10   AIRCRAFT RADIOMETRIC SURFACE  TEMPERATURE

               MEASUREMENTS,  9  AUGUST  1972


               Solid  curve:   measurements from 460 m

               Dashed curve:  measurements from 1220 m, 10°C added.
                               A-15

-------
     50
     40
     30
     20
     40
   UJ
   cr
     30
   DC
   UJ
   Q.
   uj 20
   H
     10
                                          (e)  1400 CDT
   111
  /• l"l
          I    t
         ,;;. ,  i''j  i.
         »i !• r> •< ",  '<•

>'  ', i;;1.,'ijl;'.- jJli./!.
.   i"!      .nlfi m
                                          (f)  1630 CDT
     30 h
     20
     10
       rVvV^^
                                          (g)  1915 CDT
" JklV^vHr    i/J^^^
                  20
                   40
                   RANGE
                        60
                        km
80        100

   SA-2322-33B
FIGURE A-10   AIRCRAFT RADIOMETRIC SURFACE TEMPERATURE
               MEASUREMENTS, 9 AUGUST 1972  (Concluded)
               Solid curve:  measurements  from  460  m
               Dashed curve:  measurements  from  1220 m,  10°C  added
                             A-16

-------
  o
25







20






15







10







 5



20







15







10
      5
  IT
  cu


  1  20
  HI
  I-

  m
  _J
  DC

  Q
15







10







 5 -



20 h







15






10 -







 5 -
                                           (d) 1145 CDT
                                           (c) 0930 COT
                                      (b) 0630 CDT
                                          (a) 0400 CDT
                                     I
                20
                          40        60


                          RANGE — km
                                          80        100




                                             SA-2322-34A
FIGURE A-11   AIRCRAFT AIR  TEMPERATURE MEASUREMENTS,

               9 AUGUST 1972


               Altitudes:  460 m (solid) and 1220  m (dashed)
                           A-17

-------
   25
   20
   15
   10
   25
   20
 LU
 CC
   15
   10
 D
 CD
   25
 CC
 Q
   20
   15
   10
               20
                                        (e) 1400 CDT
                                        (f) 1630 CDT
                                        (g) 1915 CDT
                                              J
40        60
RANGE — km
80         100

   SA-2322-34B
FIGURE A-11    AIRCRAFT AIR TEMPERATURE MEASUREMENTS,
                9  AUGUST 1972  (Concluded)
                AltitJdes:   460 m  (solid)  and  1220 m  (dashed)
                            A-18

-------
      60
      50
     40
     30
      20
      10
      30
20
   LU
   CE
   D



   E
   HI
   Q.
   in 10

   h-
   QC
   Q.


     30
     20
     io
     30 -
     20 -
     10
                       \      '    I
                                                 I     r
20
                                         (d) 0900 CDT
                                         (c)  0630 CDT
                                    (b)  0330 CDT
                                        (a) 0030 CDT
40

RANGE
                                60

                                km
                                                80          100


                                                   SA-2322-35A
FIGURE A-12   AIRCRAFT RADIOMETRIC SURFACE TEMPERATURE

               MEASUREMENTS,  11  AUGUST 1972

               Dashed curve:  measurements from  460  m, 10°C added

               Solid  curve:   measurements from 1220 m
                               A-19

-------
     60
     50
     40
     30
     20
  p 50
     40
   DC

   LLJ
     30
   DC 20
   Q-
     50
     40
     30
     20
     10
            .»$;   ?
            r  *w
                                  I    I     r
                                    (e)  1130 CDT
                                    (f)  1400 CDT
                                    (g)  1630 CDT
                         I
                20
                        40


                        RANGE
60


km
80       100





  SA-2322-35B
FIGURE A-12   AIRCRAFT RADIOMETRIC SURFACE TEMPERATURE


              MEASUREMENTS,  11 AUGUST 1972  (Concluded)



              Dashed  curve:  measurements from 460 m, 10°C added


              Solid curve:  measurements from  1220 m
                          A-20

-------
     30
     25
     20
     15
     25
     20
     15
  OC
     25
  LU
  I-
     20
  DC
  Q  15
     25
     20
     15
     10
-,-'."*"'
                 20
                                      1     '     I
                                        Id)  0900 CDT
                                        (c)  0630 COT
                                        (b)  0330 CDT
                                        (a)  0030 CDT
                                                I
                           40        60
                           RANGE — km
                                        80        100

                                         SA-2322-35A
FIGURE A-13    AIRCRAFT AIR TEMPERATURE MEASUREMENTS,
                11  AUGUST  1972
                Altitudes:   460 m  (dashed) and  1220  m (solid)
                            A-21

-------
   30
   25
   20
   35
 o
   30
 oc

 525
 X
 HI
 Q.

 HI
 K 20
 co
 cc
 Q
   35
   30
   25
   20
    15
j*^-*-^r^vvv>*v^r^^^^^
                                    (el  1130 CDT
                                    (f)  1400 CDT
                                    (g)  1630 CDT
               .'V.'.-
                                            I
               20
                 40        60
                 RANGE — km
80       100


  SA-2322-35B
FIGURE  A-13   AIRCRAFT AIR  TEMPERATURE MEASUREMENTS,
              11 AUGUST  1972  (Concluded)

              Altitudes:  460 m (dashed)  and  1220 m  (solid)
                         A-22

-------
             40
             30
             20
             10
             30
             20
             10
             30
          I-
          ir  20
             10
          H
          tt
             30
             20
             10  -
             10  -
                                       (a)  1700 CST
                                       (bl  1930 CST
                                       (c)  2230 CST
                                       (d)  0130 CST
                                       (e)  0430 CST
                      20
                              40      60
                            RANGE — km
80     100

SA-2322-36
FIGURE A-14   AIRCRAFT RADIOMETRIC  SURFACE
               TEMPERATURE  MEASUREMENTS,
               23-24 APRIL 1973
               Dashed curve:  measurements from 460  m, 10°C added
               Solid curve'   measurements from 1220 m
                               A-23

-------
                               REFERENCES
1.  H. E. and K. Lettau, "Exploring the World's Driest Climate:  Scientific
    Results of the University of Wisconsin Field  Studies  during July  1964,
    in the Peruvian Dessert (Pampa de la Joya), pre-publication draft,
    Madison, Wisconsin (1971).

2.  E. E. Uthe, "Lidar-Derived Aerosol Structure  over St. Louis, Missouri,
    during METROMEX 1972',' Interim Report, NSF Grant GI-34770, Stanford
    Research Institute, Menlo Park, California  (1972).

3.  Physics of Plant Environment, W.  R.  VanWijk,  Ed., (North-Holland
    Publishing Company, Amsterdam, 382 pp, 1963).

4.  W. C0 Swinbank, "Long-Wave Radiation from Clear Skies" Quarterly
    Journal of the Royal Meteorological Society,  381, 339-348 (1963).

5.  W. F. Dabberdt, "Climatonomy of the Antarctic Plateau," paper presented
    at the Conference on Planetary Boundary Layers, 18-21 March 1970,
    sponsored by IUGG, IAMAP, and AMS,  Boulder, Colorado.

6.  E. Kung, "Climatology of Aerodynamic Roughness Parameter and Energy
    Dissipation in the Planetary Boundary Layer over the Northern Hemisphere,
    Section 2 of Studies of the Effects of Variations in Boundary Conditions
    on the Atmospheric Boundary Layer,  Department of Meteorology, University
    of Wisconsin, Annual Report Contract DA-36-039-AMC-00878, USAERDA, Ft.
    Huachuca, Arizona (1963).

7.  H. Panofsky, and G. N.  Brier, Some Applications of Statistics to
    Meteorology, (Mineral Industries  Continuing Education, Pennsylvania
    State University, University Park,  Pa. 224 pp, 1965).

8.  S. Changnon, "1972 Operational Report for METROMEX',' Illinois State
    Water Survey, Urbana, Illinois (1972).

9.  H. H. Lettau, Micrometeorology Syllabus, Meteorology 403, Department
    of Meteorology, University of Wisconsin, Madison, Wisconsin (1968).
                                   R-l

-------