MODELING WIND-INDUCED CIRCULATION IN THE HOMOGENEOUS LAKE-CONSTANCE USING K-EPSILON CLOSURE

Barotropic models of wind-driven circulation commonly use vertical edd y-viscosities which are prescribed functions of depth and applied wind speed rather than a parameterization that is dictated by the turbulen ce intensity We use a first order k-epsilon-closure to do this and dem onstrate important qualitative differences with this classical turbule nce closure in the pattern of wind induced barotropic currents in idea l basins: as well as in Lake Constance: penetration and Ekman layer de pths respond with some delay time to the applied wind history as does the attenuation of inertial oscillations established by the wind. This also affects the topographically-induced current pattern. We demonstr ate these features by subjecting the homogeneous Lake Constance to imp ulsive and spatially uniform external wind forcing of different streng ths in the long direction. Specifically, the shallow-water equations a re coupled via the vertical eddy-viscosity with the correspondingly ap proximated balance laws of turbulent kinetic energy and its dissipatio n, which are then solved numerically.