BAROCLINITY AND NONLINEAR EKMAN PUMPING DYNAMICS

With the Ekman momentum approximation,the influence of atmospheric baroclinity on the dynamics of boundary layer is studied.Some new results are obtained.These results show that the atmospheric baroclinity plays an important role in altering the horizontal velocity of Ekman boundary layer and its angle with the horizontal wind velocity component near the surface.There are three different physical factors affecting the nonlinear Ekman suction,the vertical motion at the top of boundary layer:first,barotropic geostrophic relative vorticity at the ground;second,the thermal wind vorticity induced by the baroclinity;and third,the nonlinear interaction between the barotropic geostrophic relative vorticity and the baroclinic thermal wind vorticity.These results may provide a better physical basis for the parameterization of boundary layer and the interpretation of the numerical modeling results.