Wind‐forced motions in stratified lakes and their effect on mixed‐layer shear

The solution for the response of a rectangular, n ‐layered, stratified lake to an arbitrarily varying (in time) wind stress is presented. The case n = 3 is considered in detail. For a three‐layered lake the response is made up of the individual responses of one external and two internal modes. When the upper layer is shallow relative to the other two layers, the mixed‐layer shear is due almost entirely to the slower, second‐mode response. Moreover, the upper interface can tilt quite severely while the lower interface remains nearly flat. Calculations based on the three‐layer model are compared with measurements made in Wellington Reservoir, Western Australia.