EPA-600/3-77-056
May 1977
Ecological Research Series
SATELLITE REMOTE SENSING STUDY OF THE
TRANS-BOUNDARY MOVEMENT OF POLLUTANTS
Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Duluth, Minnesota 55804
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The*nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems are assessed for their long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/3-77-056
May 1977
SATELLITE REMOTE SENSING STUDY
OF THE TRANS-BOUNDARY MOVEMENT
OF POLLUTANTS
by
C. T. Wezernak and D. R, Lyzenga
Environmental Research Institute of Michigan
Ann Arbor, Michigan 48107
Grant No. R803671
Project Officer
Michael D. Mullin
Large Lakes Research Station
Environmental Research Laboratory - Duluth
Grosse He, Michigan 48138
ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
DULUTH, MINNESOTA 55804
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DISCLAIMER
This report has been reviewed by the Environmental Research Laboratory-
Duluth, U.S. Environmental Protection Agency, and approved publication.
Approval does not signify that the contents necessarily reflect the views
and policies of the U.S. Environmental Protection Agency, nor does mention
of trade names on commercial products constitute endorsement or recommenda-
tion for use.
ii
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FOREWORD
Our nation's freshwaters are vital for all animals and plants, yet our
diverse uses of water — for recreation, food, energy, transportation, and
industry — physically and chemically alter lakes, rivers and streams. Such
alterations threaten terrestrial organisms, as well as those living in water.
The Environmental Research Laboratory in Duluth, Minnesota develops methods,
conducts laboratory and field studies, and extrapolates research findings
— to determine how physical and chemical pollution affects
aquatic life
— to assess the effects of ecosystem on pollutants
— to predict effects of pollutants on large lakes through
use of models
— to measure bioaccumulation of pollutants in aquatic
organisms that are consumed by other animals, including
man.
/
This report demonstrates the usefulness of satellite based remote sensing
in delineating the large-scale water quality in large lakes. The capability
to assess a whole lake, in conjunction with normal chemical and physical
analyses, has significance in monitoring the Great Lakes.
Donald I. Mount, Ph.D.
Director
Environmental Research Laboratory
Duluth, Minnesota
iii
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ABSTRACT
A limited analysis of ERTS (LANDSAT) data of the western basin of Lake
Erie and the southern portion of Lake Huron was performed. The objective of
the program was to depict the large-scale movement of water masses, as mani-
fested in terms of suspended solids, and to demonstrate the use of ERTS data
in large lakes monitoring. ERTS (LANDSAT) data, as recorded on computer
compatible tapes, were processed to display surface circulation features,
surface suspended solids distribution, surface chlorophyll distribution, and
secchi disc transparency. The results demonstrate the potential of satellite
remote sensing for monitoring of large water bodies.
This report was submitted in fulfillment of Grant No. R803671-01-0 by
the Environmental Research Institute of Michigan under the sponsorship of the
Environmental Protection Agency. Work was completed as of January 1976.
iv
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CONTENTS
Foreword ±±±
Abstract iv
List of Figures vi
Acknowledgements vii
1. Conclusions , 1
2. Recommendations 2
3. Introduction 3
4. Methods 4
5. Results and Discussion 5
Transparency - Lake Erie 5
Chlorophyll - Lake Erie 6
Suspended Solids - Lake Erie 9
Surface Circulation - Lake Eire 12
Lake Huron 12
References 17
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FIGURES
Number Page
1 Transparency, Western Basin Lake Erie, 2 June 1974 8
2 Second Derivative versus Phytoplankton Concentration 10
3 Surface Chlorophyll, Western Basin Lake Erie, 13 June 1975 . . 11
4 Suspended Solids, Western Basin Lake Erie, 13 April 1975 ... 13
5 Surface Circulation Features, Lake Erie, Pelee Island
Area, 4 April 1975 14
6 Southern Lake Huron, 20 June 1974, E-1697-15393 15
7 Southern Lake Huron, 2 June 1974, E-1679-15400 16
vi
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ACKNOWLEDGEMENTS
Several individuals at ERIM contributed to the project. In particular
the assistance of Mr. F. G. Sadowski in generating the ERTS products is
acknowledged with sincere thanks. Likewise the assistance of Large Lakes
Research Station (formerly the Grosse lie Laboratory) personnel in providing
water quality data is greatly appreciated.
vii
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SECTION 1
CONCLUSIONS
The synoptic view provided by ERTS (LANDSAT) provides signigicant infor-
mation concerning suspended solids distribution and general surface circula-
tion in the western basin of Lake Erie and Southern Lake Huron. High concen-
trations of suspended solids are typical along the Canadian shore of Southern
Lake Huron and throughout the western basin of Lake Erie. In the latter case,
high suspended solids concentrations are largely due to loading from the
Maumee River, the Detroit River and resuspension of bottom sediments.
The four broad ERTS "(LANDSAT) bands, which span the spectral range
0.5 - 1.1 ym, offer a water quality measurements potential which is essential-
ly restricted to suspended solids, turbidity, transparency, and the detection
of phytoplankton blooms. Attempts to correlate LANDSAT data with other sub-
stances in aqueous solution or suspension would be difficult to justify in
scientific terms. A large variance in suspended sediment concentration con-
stitutes an interference in the processing of data to display chlorophyll
levels. Generally these ambiguities cannot be resolved solely on the basis
of LANDSAT data analysis and reference to ground truth measurements for cali-
bration purposes are necessary.
The data acquired from space and ship data are complimentary and neither
can substitute for the other. The large area coverage provided from space can
serve to provide unity to data collected by conventional point sampling and
facilitate the interpretation of data collected by conventional methods.
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SECTION 2
RECOMMENDATIONS
A continuing program of analysis of LANDSAT data for the two study areas
discussed in this report is recommended. Repeat data under a variety of wind
and lake-state conditions would contribute significantly to the information
data base, facilitate interpretation of point sampled data, and aid in trend
analysis.
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SECTION 3
INTRODUCTION
The objective of the program were to delineate the large-scale distribu-
tion of water masses of markedly different water quality in the Western Basin
of Lake Erie and Southern Lake Huron through the analysis of ERTS (Earth
Resources Technology Satellite) data. In January 1975, the satellite was re-
named LANDSAT, with the result that both names are used interchangeably in
reference to data collected prior to 1975.
The intent of the program was to examine and process ERTS (LANDSAT) data
for purposes of providing s'ome insights into the general movement of water
masses and also to provide information regarding suspended solids, trans-
parency and phytoplankton, to the extent possible. The program, as originally
defined, was limited to the analysis of three scene dates. The following ERTS
(LANDSAT) scenes were examined in the analysis:
1. E-1679-15403 2 June 1974 W. Lake Erie
2. E-2081-15355 13 April 1975 W. Lake Erie
3. E-1985-15290 4 April 1975 W. Lake Erie
4. E-1697-15393 20 June 1974 S. Lake Huron
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SECTION 4
METHODS
The data used in the analysis were collected by the ERTS (LANDSAT)
satellite from an altitude of approximately 915 km in the following spectral
bandsl:
Spectral Band Wavelength (urn)
4 0.5 - 0.6
5 0.6 - 0.7
6 0.7 - 0.8
7 0.8 - 1.1
The area of each resolution element is approximately 0.45 hectares. The in-
formation in bands 4, 5, and 6 is recorded with a 7-bit resolution (127 data
levels), and in band 7 with a 6-bit resolution (63 data levels). Since the
system was not optimized for data collection over water, the total information
content was contained within a small range of data levels.
The processing of ERTS (LANDSAT) data recorded on computer-compatible
tapes included density-level slicing of individual spectral bands, statisti-
cal analysis of selected target areas, and a modified second-derivative
analysis. The general processing procedure included: (1) reformatting of
the data, (2) preparation of working grey maps, (3) production of line prints
through selected target areas, and (4) production of the final product. The
final computer produces were generated using the hard-copy color output sub-
system of the MIDAS (Multivariate Interactive Digital Analysis System) deve-
loped at ERIM.
Ground-truth data were provided by the Large Lakes Research Station.
Limited data were available for 2 June 1974 (¥. Lake Erie) and 20 June 1974
(Lake Huron).
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SECTION 5
RESULTS AND DISCUSSION
The program of analysis was centered around the available ground-truth
data. Of the three parameters of concern in this investigation, suspended
solids, transparency, and chlorophyll; ground-truth data were available for
the last two parameters for use in the Lake Erie analysis.
TRANSPARENCY - LAKE ERIE
Based on the Beer-Lambert law, an exponential correlation between the
output signal and Secchi disc transparency can be expected. The problem re-
mains, however, of calibrating the calculated radiance data with the available
ground-truth information. Because of atmospheric path radiance considera-
tions, band 5 was selected over band 4 for the examination of the relationship
between Secchi disc transparency and radiance data and the production of the
final map.
Using Turner's atmospheric model2, an atmospheric correction was calcu-
lated for the condition of: (1) solar,zenith angle of 31°, (2) visibility of
23 km., and (3) a marine atmosphere. The resulting path radiance for band 5
(centered at X = 0.65 ym) was 0.170 mw cm"2 sr"1. Using the ERTS conversion
factors published in the ERTS User's Handbook1, the data level equivalent (as
recorded on the computer compatible tape) was calculated to by 10.8, This
value compares with an observed data level of 9.88 (average of 441 resolution
elements) over an area of relatively clear water in the central basin of Lake
Erie. The latter value was accepted as the path radiance data level equiva-
lent for use in applying the atmospheric correction to the data set. The
effect of background albedo on the observed signal was not considered in this
analysis.
Using the available ground-truth data, the following equation was derived
for use in the Western Basin of Lake Erie:
log L5-1.869
T = -0.392
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where,
L,. = radiance x 10, band 5
T = Secchi disc transparency, meters
The term L- in the above experession was calculated as follows:
L5 = (D5-DA(5)) (0.0157 mw cnf^r"1) (2)
where,
D = data value recorded on ERTS CCT, band 5
D , , = path radiance, band 5, data value equivalent
A comparison of calculated versus measured transparency is presented in Table
1. It should be noted in Table 1 that the time of field measurements varied
by as muqh as six hours from the time of satellite data collection. The
small amount of data precludes any statistical analysis of calculated versus
measured results.
The resulting transparency map is shown in Figure 1. The results are in
general agreement with field measurements for 2 June 1974. In this regard it
should be stressed that close agreement between measured and calculated values
may be visible by correcting for the effect of phytoplankton on the observed
signal. Because of the limited scope of this investigation, this factor was
not examined.
CHLOROPHYLL - LAKE ERIE
From a scientific standpoint, no satisfactory method for the measurement
of surface chlorophyll, using existing ERTS (LANDSAT) data is possible. The
positioning of the spectral bands, the number of spectral bands, and various
other instrumental characteristics preclude the development of satisfactory
algorithms for processing ERTS 1, 2 (LANDSAT 1, 2) data for surface chloro-
phyll measurement, applicable to a wide range of conditions. Consequently,
various investigators have relied on empirical methods to extrapolate field
measurement over a given study area. The processing technique used range from
slicing of a single band to the use of ratios. The use of the ratio band 6/
band 5 has been previously discussed and found to be suitable only in the case
of high chlorophyll concentrations and relatively homogeneous waters3.
The technique adopted in this investigation involves the use of bands 4,
5, 6 to examine the interrelationship of the signal in the three bands. In
general terms, an increase in phytoplankton will tend to increase the signal
in band 4, decrease the signal in band 5, and increase the signal in band 6.
These interrelationships can be evaluated by calculating a quasi-second de-
rivative of the spectrum at A = 65 ym, as follows:
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Table 1. SECCHI DISC TRANSPARENCY, WESTERN BASIN LAKE ERIE
2 June 1974
E-1679-15043 (1104 EDT)
Station
56
57
58
59
60
61
70
75
Central
Basin
Time
(EDT)
1745
1613
757
939
1320
1440
1103
1220
Transparency (meters) Radiance Band 5
Meas. Calc. (mw • cm~2sr~1)100
2.9
2.0
2.2
1.8
1.7
2.2
1.0
1.8
4.0
2.3
2.7
2.5
2.2
2.2
2.2
1.0
2.2
4.0
9.6
6.5
8.0
10.4
10.4
10.4
29.6
10.4
2.06
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-I*
H-
(W
MICHIGAN
TRANSPARENCY
(SICOI MSC DEPTH
KSIEM USIN LAKE EM
im
U
12
IB
it
•IB
-------
,2
(.65) = L - 2L + L (3)
dA.
where 1,4, L5, Lg equal the radiances in bands 4, 5, and 6 respectively. The
relationship between the second derivative, using ERTS bands, and phytoplank-
ton concentration (expressed as the extinction coefficient) is shown in
Figure 2. The curves are based on calculated reflectance spectra using the
Suits AQUACAN model"* . Since chlorophyll concentrations are a function of
cell size, species, physiological state, etc., phytoplankton concentrations
are expressed as the extinction coefficient. This means that in practice the
curves must be calibrated by field sampling at a given study location.
Although calculations indicate that the above approach is less sensitive
to turbidity differences than working with individual bands the fact remains
that a large variance in terms of suspended sediments will produce ambiguities
which cannot be resolved on the basis of spectral analysis alone. In cases
where turbidity may vary by a factor of 10 or less, turbidity (at low or
moderate levels) will not seriously affect the results.
Surface chlorophyll for 2 June 1974 is shown in Figure 3. Once again,
because of limited ground-truth data a statistical analysis of measured ver-
sus calculated results is not possible. Only enough data were available to
allow calibration. Nevertheless, the results appear very reasonable and in
line with expectations at key points in the scene. Field measurements indi-
cate a surface chlorophyll concentration of 10 mg/m3 on the east side of the
Detroit River and concentrations of approximately 7 mg/m3 to the west of the
islands. Very high suspended solids in the areas indicated as "undefined",
precluded any meaningful analysis in these areas.
SUSPENDED SOLIDS - LAKE ERIE
In spite of a lack of ground-truth data, an analysis was performed to
show the suspended solids distribution in the western basin on 13 April 1975,
Because of a lack of confirming data the concentrations are considered rela-
tive.
The approach involved the use of a previously developed empirical equa-
tion3 . An atmospheric correction was calculated using the Turner model2.
The calculated atmospheric parameters (band 5) for a solar zenith angle of
42° and a visibility of 23 km., were as follows:
^A = 0.129 mw cm sr
T = 0.75
E = 10.77 mw cm"
-------
u
cE
Id
Q
Q
02
u
u
CLEAR (O.OOl)
TURBID(O.IO)
1
0-1 0.2
PHYTOPLANKTON S(M )
0.3
Figure 2. Second Derivative versus Phytoplankton Concentration
10
-------
-
OJ
•
-
TJ
-
-
ONTARIO
MICHIGAN
OHIO
PHYTOPLANKTON
SURFWJ cunipru
CWCENTMTHIB
WESTERN BASIH LAKE ERIE
INK Iff!
•/•>_ «/•>
D
-------
where,
L. = path radiance
A
T = transmittance
E = total downward irradiance at the water surface
The expression used in the analysis were:
C = 0.03991 [(L5-LA(5)) ^ x 100]2'8216 (4)
where,
C = suspended solids (mg/&)
Lc = radiance at satellite altitude, band 5
L.x,.\ = path radiance, band 5
T = transmittance, band 5
E = total downward irradiance at water surface, band 5
The resulting map showing surface suspended solids distribution is presented
in Figure 4.
SURFACE CIRCULATION - LAKE ERIE
A portion of frame E-1985-15290, 4 April 1975, was processed to show the
dynamic surface circulation patterns in the vicinity of Pelee Island. The
resulting map is presented in Figure 5. The general movement around Pelee
Island in a southeasterly direction has been frequently observed in the exam-
ination of satellite data of the area.
LAKE HURON
The attempt to find a suitable ERTS (LANDSAT) data set of the southern
portion of Lake Huron, at a time when ground-truth data were collected, proved
unsuccessful. Limited ground-truth data were collected on 20 June 1974;
however, unfavorable atmospheric conditions prevented a meaningful analysis of
the satellite data. A working grey map of the area was produced and a statis-
tical examination of all four bands were performed. The results indicated
that the scene contained thin clouds and possibly ground fog; and that further
analysis was unwarranted. The area was also partly obscurred by clouds on
2 June 1974. The above scenes are shown in Figures 6 and 7. The high tur-
bidity pattern along the east side of the lake has been frequently observed in
the examination of satellite data of this region.
12
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-
H-
-------
TJ
H-
Ln
(D C
I— fl
ro i-h
fD to
n
en
(-•
OJ
3
n
n
ro
03
o
3
xt cu
f-l rr
H- C
M i-l
CD
M Cfl
r1
03
-
SURFACE
CIRCULATION
FEATURES
UK HE
PElEt ISLAM AKA
(MtOB
.
IMC
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Figure 6. Southern Lake Huron, 20 June 1974, E-1697-15393
15
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-
Figure 7. Southern Lake Huron, 2 June 1974, E-1679-15400
16
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REFERENCES
1. National Aeronautics and Space Administration, Data Users Handbook.
Goddard Space Flight Center, Greenbelt, Maryland, 1972.
2. Turner, R.E. Radiative Transfer in Real Atmospheres, Environmental
Research Institute of Michigan, Ann Arbor, Michigan, Report 190100-24-T,
1974.
3. Wezernak, C.T. Water Quality Monitoring Using ERTS-1 Data, Environmental
Research Institute of Michigan, Ann Arbor, Michigan, Report NASA-CR-ERIM
193300-55-F, March 1975, 87 pp.
4. Suits, G. Preliminary Results of Water Reflectance Calculations Using
AQUACAN. Environmental Research Institute of Michigan, Ann Arbor,
Michigan, Unpublished Memo, January 1973.
17
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/3-77-056
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
SATELLITE REMOTE SENSING STUDY OF THE TRANS-
BOUNDARY MOVEMENT OF POLLUTANTS
5. REPORT DATE
May 1977 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
C.T. Wezernak and D. R. Lyzenga
8. PERFORMING ORGANIZATION REPORT NO.
ERIM 115100-2-F
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Environmental Research Institute of Michigan
Infrared and Optics Laboratory
Post Office Box 618
Ann Arbor, MI 48107
10. PROGRAM ELEMENT NO.
1BA608
11. CONTRACT/GRANT NO.
Grant No. R803671
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Research Laboratory - Dul., MN
Office of Research and Development
U.S. Environmental Protection Agency
Duluth, Minnesota 55804
13. TYPE OF REPORT AND PERIOD COVERED
Final Report
14. SPONSORING AGENCY CODE
EPA/600/03
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A limited analysis of ERTS (LANDSAT) data of the western basin of Lake Erie and the
southern portion of Lake Huron was performed. The objective of the program was to
depict the large scale movement of water masses, as manifested in terms of suspended
solids, and to demonstrate the use of ERTS data in large lakes monitoring. ERTS
(LANDSAT) data, as recorded on computer compatible tapes, were processed to display
surface circulation features, surface suspended solids distribution, surface
chlorophyll distribution, and secchi disc transparency. The results demonstrate the
potential of satellite remote sensing for monitoring of large water bodies.
This report was submitted in fulfillment of Grant No. R803671-01-0 by the Environ-
mental Research Institute of Michigan under the sponsorship of the Environmental
Protection Agency. Work was completed as of January 1976.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Remote Sensing
Monitors
Detectors
Eutrophication
Lake Erie
Lake Huron
Suspended Solids
Satellite
Imagery
08/H
13. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
26
20. SE
22. PRICE
EPA Form 2220-1 (9-73)
18
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