An array of 15 moorings, supporting current meters at 15 and 50 m depth, was in place in Lake Michigan from June 1982 to July 1983. Six moorings surrounded the southern basin on about the 75 m&bath, six closely spaced moorings transected the mid-lake ridge and adjacent valley, and three moorings occupied the centers of the southern and northern basins. In the southern basin, monthly-averaged currents are weakly anticyclonic during June and July, cyclonic during the rest of the year, and most intense during March. Temperatures and bidaily-averaged currents both show the effects of the gravest (4-day period) vortex-mode oscillation. Also, it is shown that the seasonal thermocline became well established much earlier in 1983 (early June) than in 1982 (middle August).

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