Studies on water movements and sediments in Southern Lake Michigan : part 1[-3] ... / by John C. Ayers.

Data from 1961 were from Chicago Outer Buoy; 1962 and 1963
data were taken at the diffuser position. The data of 1961
are reversing thermometer data; those of 1962 and 1963 are
bathythermograph data. Dashed isotherms for 70 and 120 are
estimates supported by data on only one side.
Figure 8, from Ayers (1962), has been provided to enable
comparisons with deep-water conditions. A line indicating
16 meters of depth (the depth near the diffuser) has been
drawn across this figure to aid in the assessment of depth as
a factor in the local regimen.
As a test of the comparability of the years involved in
Figures 7 and 8., (Chicago temperatures since 1960 being unavailable) we have compared the annual mean raw-water temperatures of-the Milwaukee filtration plant for these years:
1941- 76o60c 1961 6.o6~c
1942 6.560C 1962 6.560C
1963 6.78 0C
1941 and 1961 appear to have been somewhat warmer and cooler,
respectively,, than the other years, but 1942, 1962, and 1963
appear to be reasonably comparable. Since the latter three
years comprise the bulk of both figures, comparisons between
the figures seem justified.
Midsummer surface temperatures off Chicago attain higher
values than those in the open lake. Both spring and fall
temperatures are higher off Chicago than in midlake. More
effective downward mixing of heat in spring is apparent off
Chicago where the first isotherm to show a curvature indicative
of developing stratification is that for 10Q while in midlake
the 50 isotherm develops a curvature above 16 meters, also in

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