Intensification of Upper-Trospheric Currents Due to Ekman Friction

The dynamics of zonal quasi-geostrophic currents was studied within the framework of a two-level quasi-geostrophic model with bottom friction. It is shown that due to friction the flow velocity at the lower level drops to zero, while the velocity at the upper level increases. An analytical expression for the maximum flow velocity at the upper level is obtained, and the dependence of the amplification factor on the structure of the initial velocity disturbance is investigated. A similar result is obtained within the framework of a continuous surface geostrophic model using the long-wave approximation. An analytical solution is constructed that describes the transformation of the zonal flow into an intense upper-tropospheric flow. Thus, it is shown that Ekman friction is one of the important mechanisms that contribute to the intensification of currents at the upper level.