Momentum coupling in ocean-atmosphere models

A simple model of ocean dynamics is presented in which: (a) the mean momentum balance in the mixed layer is controlled by the wind stress and the net effect of the understress and the interfacial stress and below the mixed layer by a balance of the interfacial stress and the form drag at the ocean bottom, as proposed by Johnson and Bryden (1989), (b) the energetics of the oceanic eddy field are determined by a balance between dissipation by the understress and the supply of turbulent kinetic energy from below the mixed layer; and (c) the vertically well mixed condition of the mixed layer is maintained by the near surface shear due to the surface wind. When applied to steady-state, horizontally homogeneous conditions, the model predicts properties of the coupled ocean atmosphere system, which are found to be approximately valid in the closest example of such conditions in the World ocean, namely the Antarctic Circumpolar Current, driven by the mid-latitude Westerly winds.