The surface current circulation patterns of southern Lake Michigan were charted for all cardinal and subcardinal wind directions, employing LANDSAT-1 observations of the distribution of natural tracing material borne in the surface waters. These colorants consist chiefly of river discharges composed of suspended sediments, pollutants, and algae; extensive chemical precipitations proved valuable for areas farther from shore. Comparison of the satellite-derived surface current charts with previous theoretical and empirical studies shows good agreement

Strong, A. E.

Stumpf, H. G.

English

NASA Technical Reports Server

SURFACE CIRCULATION IN THE GREAT LAKES • M-5
AS OBSERVED BY LANDSAT-1
AUGUST 1972-DECEMBER 1973:
SOUTHERN LAKE MICHIGAN
By Harry G. Stumpf and Alan E. Strong
National Environmental Satellite Service,. NOAA, Suitland, Maryland
ABSTRACT
The surface current circulation patterns of southern Lake Michigan have been charted
for all cardinal and subcardinal wind directions, employing LANDSAT-1 observations of the
distribution of natural tracing material borne in the surface waters. These colorants
consist chiefly of river discharges composed of suspended sediments, pollutants, and
algae; extensive chemical precipitations proved valuable' for areas farther from shore.
Comparison of the satellite-derived surface current charts with previous theoretical
and empirical studies shows good agreement.
INTRODUCTION
The LANDSAT-1 (formerly ERTS-1) system has added a new dimension to physical
oceanography and limnology. Conditions permitting, scientists are now able to chart
circulation patterns using natural tracing material borne in the surface waters. These
colorants are chiefly turbidities from river discharges consisting chiefly of suspended
sediments, pollutants, algae or natural dyes. Occasionally chemical precipitations are
noted, in the-imagery (Figure 1); these, too, can be employed as circulation tracers, and
.they are particularly useful in areas farther from shore. Other sources of information
are suspended sediment plumes originating from areas of shoreline erosion.
Synoptic oceanographic or limnologic investigations have always been difficult, if
not impossible, from surface vessels. Circulation patterns are constantly being altered
by changing meteorological conditions. The observation of naturally-occurring tracers
from space, as a near-instantaneous "snap'shot", provides circulation information that .
should relate to the meteorological influences at and immediately prior to the time of
the satellite imagery. . . .
. . . .METHOD OF ANALYSIS-
Ayers (ref. 1,) has developed an empirical relationship that takes into account the,large
time lag between the onset of a given wind condition and the response of the surface
circulation to this wind. A complete response of current to the wind requires many hours,
or even several days. • In Ayers' formula the resultant effective wind stress relationship
is such that the forcing influence of the previous day is one-half that of the given day.
In this Great Lakes investigation we have chosen to utilize three days of wind data prior
to each LANDSAT-1 scene. In addition, to emphasize the 24-hour period immediately prior
to the satellite.data, we have represented the 6-hourly winds-as a weighted resultant
stress vector as follows:
W(day 1) = ""(-24) + 2"(-18) + 3"(-12) + ^ (- 6)
10
The subscript after each'vector wind observation denotes observation time (hours) before
1973
https://ntrs.nasa.gov/search.jsp?R=19760010490 2020-03-22T16:15:16+00:00Z
noon of the day of the LANDSAT-1 observation.
A final vector resultant wind for the three-day period was obtained using the follow-
ing formula:
• ~"= "(day 3) + 2"(day 2) +
For a more rigorous relationship one must take into account additional parameters
such as atmospheric stability over the water, wave conditions, and current locations as
a function of. the distance to shore (ref. 2). Much of this fine-tuning, however,
is not very realistic with the present paucity of wind data. In this study
we have chosen to use the U.S. Coast Guard weather observations from shore installa-
tions rather than inland sites. Although these winds may suffer somewhat due to local
anomalies in the wind field (e.g., lake breeze circulations), they are felt to be the most
representative of true lake winds.
Circulation vectors have been- extracted from each LANDSAT-1 scene using all natural
or man-made tracers in the surface waters available to the analyst. As an illustrative
example , the interested reader should compare the circulation derived for southern Lake
Michigan under a northerly resultant wind (Figure 2) with the "whiting" image (Figure 1);
the authors have discussed these extensive precipitations of calcium carbonate in detail
elsewhere (refs. 3 and k) . Although complex, much of the analysis is straightforward
in the hands of a trained interpreter. . ,
Charts were prepared for all cardinal and subcardinal resultant wind directions
(i.e., N, NE...NW). . Some LANDSAT-1 observations of currents under a few wind directions
were not available during the study period (August 1972 to December 1973). Whenever more
than one LANDSAT-1 observation was used in a given area, the currents presented are com-
posites. Although most of the current charts are based on only one LANDSAT-1 pass, if two
scenes were available1 for a given resultant wind direction the observation under the
stronger wind stress was generally used. It should be mentioned that circulation varia-
tions should be expected under weaker or stronger resultant wind stresses from the same
direction. We have chosen to concentrate primarily on the direction of the wind vector
rather than vector magnitude for this 'report. .
'Figure 3 shows the area covered by any given LANDSAT-1 pass.
The major difficulty encountered in the analysis of the LANDSAT-1 images was. contami-
nation by sunglint whenever the solar elevation exceeded 55° (ref. U). Under these
high sun angle conditions, current interpretations are subject to large errors. Future
investigators should employ a sunglint-removal technique (e.g., MSS-6 minus MSS-5,
(ref. 5) for more reliable results.
DISCUSSION
The locations of .the wind information used in the preparation of the southern Lake
Michigan current charts are shown in Figure k. All locations referred to in the text are
identified on this base chart; Only incomplete wind data were available from the
Milwaukee and Muskegon Coast Guard facilities. Table I presents a summary of the
LANDSAT-1 images that were analyzed in addition to the resultant wind directions calcu-
lated from the above formulae.
Northerly Winds
Figure 2 indicates the general surface circulation established by predominantly-
northerly light/moderate winds as derived from two cloud-free LANDSAT-1 passes (16 July
1974
1973 and 21 August 1973). The latter pass (Figure 1) was particularly useful because
that date marked the occurrence of an extensive CaCOg precipitation that was especially
evident in MSS-U (ref. U). The major features established by "this wind regime are
several large gyres and distinct alongshore currents. An east shore southward current
extends from Little Sable Point to Michigan City, where it becomes deflected to
the northwest to become part of the eastern boundary of a large counterclockwise eddy off
Chicago, first described by Ayers et al. (ref. 6) and confirmed by Bellaire (ref. 7). In
this case, the eddy extends as far north as Waukegan. From Little Sable Point a branch
of the east shore current flows southwestward and becomes incorporated in a second mid-
lake counterclockwise gyre. This corresponds to the eddy noted by Bellaire (ref. 7) above
the mid-lake sill between Milwaukee and Muskegon. A third eddy has a clockwise circula-
tion and lies off Benton Harbor, Michigan, in the eastern part of the lake. This eddy
has been previously observed (refs. 6 and 7), but here it is much smaller than reported
previously. Along the Wisconsin shore at Milwaukee there may be a small nearshore
clockwise eddy; it has been previously documented (ref. 6), but the evidence in the
LANDSAT-1 images indicates only that there is a southward current some distance offshore.
Northeasterly Winds
Only one LANDSAT-1 pass was available for northeasterly wind conditions (17 July
1973), and only the Milwaukee area was sufficiently cloud-free to allow mapping of the
sediment distribution patterns (Figure 5). The outflow current begins along the Wisconsin
shore at Sheboygan and flows southward. After several days of northeasterly winds , water
is transported onto the west shore from Milwaukee to Gary and is piled up there; on the
slope 'of this wind set-up, the'water flows southward and northeastward (ref. 6).
Easterly Winds
On 11 March 1973, LANDSAT-1 passed over the southeast portion of Lake Michigan. It
was evident from the sediment patterns observed (Figure 6) that the east shore current
flowed southward from Holland to Michigan City and then westward to Chicago. Off Michigan
City is an apparent small flattened counterclockwise eddy, previously described by
Ayers et al. (ref. 6) under a similar easterly wind regime. North of Benton Harbor a branch
from the east.shore current flows southwestward toward the middle of the lake, presumably
to become part of the large clockwise gyre located along the shore between Holland and
Benton Harbor. This is the same clockwise gyre discussed under Northerly Winds and docu-
mented by Ayers et al. (ref. 6) and Bellaire (ref. 1}.
Southwesterly Winds
The current diagram (Figure 7) is a composite analysis of two LANDSAT-1 passes (10
June 1973 and 14 October 1973). The major feature evident in the figure has already been
discussed—the large clockwise gyre along the east shore between Benton Harbor and Holland.
The southward current along the east shore is very narrow under these southwesterly winds
and it was not observed to extend south beyond Benton Harbor, where it turns westward to
become incorporated into the eddy. According to the sediment distribution patterns, water
is flowing northeasterly directly offshore from Chicago to the center of the lake. This
apparent major upwelling has not been previously documented; Ayers et al. (ref. 6). and
Bellaire (ref. 7) have described fully-developed gyres at this location. Offshore currents
are indicated all along the west shore from Chicago to Sheboygan, suggesting that exten-
sive upwelling was occurring. There may be a small clockwise gyre along the west shore
at Waukegan, as suggested by Ayers et al. (ref. 6), but the satellite data are inconclusive.
Westerly Winds
Three cloud-free LANDSAT-1 passes (2h November 1972, 13 December 1972, and
U May 1973) were composited to obtain the current diagram (Figure 8). The clock-
wise eddy .along the east shore discussed above and previously (refs. 6 and 7)
apparently has enlarged considerably from its size under other wind regimes. It now
1975
extends from Benton Harbor north to Muskegon with a rather elongated shape. Between Gary
and Michigan City lies a large counterclockwise gyre, which was"discussed under Northerly
Winds. In this case, however, the gyre has been displaced to the southeast as compared
with other observations. Sediment distribution patterns suggest also the presence of a
counterclockwise eddy above:the mid-lake sill between Milwaukee and Muskegon;. apparently
a northwestward-flowing branch of the east shore southward current provides the driving
force for this gyre. This was discussed under Northerly Winds. Alongshore currents con-
verge in the Milwaukee - Racine area and then flow offshore, creating upwelling there and
contributing to the circulation of the mid-lake eddy. A similar current convergence
exists immediately north of Chicago in the Highland Park area; this offshore flow joins
the east shore eddy system in the middle of the southern basin.
Northwesterly Winds
The diagram for northwesterly wind-generated currents (Figure 9) is based solely on
one LANDSAT-1 pass (3 August 1973), which coincided with an extensive episode of calcium
carbonate precipitation that turned the entire southern basin "milky" in MSS-4 (Figure
10). The east shore southward current is very narrow alongshore. Lakeward of that
current is a long narrow band of upwelling from Benton Harbor to Muskegon; this was evi-
dent from the sunglint pattern on all four MSS bands. In the center of the lake is an
elongated clockwise eddy that was discussed above and by- Ayers et al. (ref. 6) and
Bellaire (ref. 7); this wind regime has apparently displaced this gyre from the
east shore toward the lake center. It extends from as far north as Milwaukee south to
Benton Harbor. Between Milwaukee and Muskegon lies the mid-lake counterclockwise gyre
discussed above; again it is driven by a westward branch of the east shore southward
current that forms the northern boundary of the eddy. As discussed above, there is a "
flattened counterclockwise gyre from Gary to Benton Harbor .driven by a branch current of
the large central eddy and by the east shore southward•current. Sediment-patterns indi-
cate a southward-flowing alongshore current at Chicago and suggest that a counterclockwise
eddy exists there (refs. 6 and 7)- Alongshore currents from Sheboygan to Highland Park
are narrow and southward; at Racine and Highland Park they turn offshore (eastward),
indicating upwelling at these-locations.
CONCLUSIONS
The prevailing wind direction on Lake Michigan is southwesterly, although during -
winter northwesterly stresses are common. Along the western shore the current favors a
northward direction, beginning with northeasterly.to easterly winds, and probably (no
LANDSAT-1 observations for easterly, southeasterly or southerly winds along this shore)
continuing through southwesterly winds. Along the eastern shore a southward current
appears dominant for all winds observed. South of Benton Harbor this flow reverses under
southwesterly, westerly and northwesterly winds. The nearshore area between Michigan City,
Indiana and Waukegan, Illinois contains an extremely complex circulation. Gyres•in the
central lake basin have been witnessed under southwesterly, westerly, northwesterly
and northerly resultant wind regimes. Comparison with previously-observed, specific,
localized circulations shows good agreement.
9
ACKNOWLEDGMENTS
the authors wish to express appreciation to NASA's Earth Resources Survey Program and
their support through LANDSAT Contract S-702U6-AG.
1976
REFERENCES
1. Ayers, J.C. (1959a). Great Lakes waters, their circulation and physical and chemical
characteristics. Paper presented to the Great Lakes Basin Symp., 29 December 1959,
Chicago, 111.
2. Jones, D.L. and F.R. Bellaire (1962). A numerical procedure for computing wind-
driven currents on the Great Lakes. Proc. 5th Conf. on Great Lakes Res., Publ. #9,
Great Lakes Res. Div., U. of Michigan, 9 3 - 1 0 2 . "
3. Strong, A.E. , H.G. Stumpf, J.L. Hart and J.A. Pritchard (1974). Extensive summer
upwelling on Lake Michigan during 1973 observed by NOAA-2 and ERTS-1 satellites.
Proc. 9th'Internat. Symp. on Rem. Sens. Environ., Environ. Res. Inst. of Michigan,
Ann Arbor, 923-932.
4. Strong, A.E. and H.G. Stumpf (1974). An evaluation of ERTS data for oceanographic
uses through Great Lakes studies. Final Report NASA/GSFC, Greenbelt, Md.
5. Watanabe, K. (1974). Detection of several sea states around Japan from multispectral
scanner imageries by ERTS-1. Proc. 9th Internat. Symp. on Rem. Sens, of Environ.,
Environ. Res. Inst. of Mich., Ann Arbor, 1353-1354.
6. Ayers, J.C., D.C. Chandler, G.H. Lauff, C.F. Powers and E.B. Henson (1958). Currents
and Water Masses of Lake Michigan, Great Lakes Res. Inst., U. of Michigan, 169 pp.
7. Bellaire, F.R. (1964). A comparison of methods of current determinations..Proc. 7th
Conf. on Great Lakes Res., Great Lakes Res. J)iv., U. of-Michigan, 171-178.
8. Ayers, J.C. (1959b). The Currents of Lakes Michigan and Huron, Great Lakes Res. Inst.,
U. of Michigan, 51 pp. •
1977
TABLE I - LANDSAT-1 FRAMES USED FOR SURFACE CIRCULATION
SOUTHERN LAKE MICHIGAN
CHARTS OF
Resultant
Wind Direction
N
NE
E
SE
S
SW
W
NW
Orbit #
4991
5493
5005
3220
NONE
NONE '
4489
6246
1728
1993
3973
5242
Date
16 Jul 73
21 Aug 7.3
17 Jul 73
11 Mar 73
NONE
NONE
10 Jun 73
14 Oct 73
24 Nov 72
13 Dec 72
4 May 73
3 Aug 73
ID #
1358-16040
1358-16042
1394-16030
1394-16033
1394-16035
1359-16094
1231-15591
1231-15593
NONE
NONE
1322-16042
1322-16045
1448-16021
1448-16023
1124-16043
1124-16050
1143-16102
1285-15590
1258-15592
1376-16034
1376-16041
Sun Elevation
58*
58*
50
51
52
58*
36
37
NONE
NONE
60*
61*
34
35
23
24
20
55*
56*
55*
55*
* - Solar elevation equal to or greater than 55°. (Possible sunglint
contamination and confusion with sediment features used for
circulation chartingA
1978
Figure 1. LANDSAT-1 images (MSS-4, left and MSS-5, right) obtained 21 August 1973,
showing the extent of the calcium carbonate precipitation over southern Lake Michigan.
1979
N0 10 20 30 40 5:
Figure 2. Surface current analysis as determined from turbidity patterns in LANDSAT-1
scenes. Weighted wind direction (Northerly) indicated in upper right-hand corner.
1980
ftOf
•HO'ftR
•H•oHOX0)•P
4nO(5ft0)0
 
.
G
.
H
 rc
i
1
 
H
H
 Po<y
F-g
•Hfe.
1981
0 10 20 30 40 50
Figure U. Wind station used for southern Lake Michigan (Dunne Crib-Chicago).
1982
0 10 20 30 40 50
Figure 5. Surface current analysis as determined from turbidity patterns in LANDSAT-1
scenes. Weighted wind direction (Northeasterly) indicated in upper right-hand
corner.
1983
0 10 20 30 40 50
Figure 6. Surface current analysis as determined from turbidity patterns in LANDSAT-1
scenes. Weighted wind direction (Easterly) indicated in upper right-hand corner.
1984
sw
0 10 20 30 40 50
QritO
Figure 7. Surface current analysis as determined from turbidity patterns in LANDSAT-1
scenes. Weighted wind direction (Southwesterly) indicated in upper right-hand
corner.
1985
w0 10 20 30 40 50
Figure 8. Surface current analysis as determined from turbidity patterns in LANDSAT-1
scenes. Weighted wind direction (Westerly) indicated in upper right-hand corner.
1986
NW
SCALE IN MILES
I 1 I
Nc.o./low^FJ; .^^ .^
'
0 10 20 30 40 50
Figure 9. Sxirface current analysis as determined from turbidity patterns in LANDSAT-1
scenes. Weighted wind direction (Northwesterly) indicated in upper right-hand
corner.
1987
Figure 10. LANDSAT-1 images (MSS-U, left and MSS-5, right) obtained 3 August 1973,
showing the extent of the calcium carbonate precipitation over southern Lake
Michigan.
1988


Surface circulation in the Great Lakes as observed by LANDSAT-1 August 1972 - December 1973: Southern Lake Michigan

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