Observation of Ekman Veering at the Bottom of Lake Michigan

An experiment in 100 m of water off the east coast of Lake Michigan during 1984 provided continuous current velocity recordings at four levels located from 1 m to 9 m above the lake bottom and also at 50 m. Near-inertial-period current oscillations were prominent and superimposed on longer-period velocity variations. Current speed at 1 m elevation varied from less than the threshold speed of the Savonious rotor sensor to 13 cm s −1. Profiles of current speed were close to logarithmic during many episodes of measurable currents over a 4-month-long recording interval. Over 50% of hourly-averaged profiles were in the nearly-logarithmic category (R > 0.987) during the month of September 1984. Veering averaging 11° was observed between low-pass-filtered current velocities measured at elevations of 1 m and at 9 m. Boundary layer theories developed from ocean studies are surveyed and the Lake Michigan data are examined from that perspective.