LEE CYCLOGENESIS .2. NUMERICAL-STUDIES

The effect of topography on the evolution of a disturbance in a barocl inically unstable mean flow is studied using a three-dimensional primi tive equation model. A procedure is developed to compare control integ rations with no topography with integrations that contain topography. It is found that lee cyclogenesis is caused primarily by the superposi tion of a growing baroclinic wave with a steady, orographically forced wave of the same scale. Some additional lee growth is found that may be orographically enhanced, or it may be related to certain small prob lems in the experimental set up. As the disturbances move over the rid ge, they are deflected to the north on the upwind side before returnin g to their original latitudes on the lee side. The numerical results i n this paper are in general agreement with the authors' previous analy tic study.