Topographic effects on the mean tropospheric flow patterns around Antarctica

Abstract

A circular tank of fluid was brought to a state of near-rigid clockwise rotation, and a topographic model of the Antarctic continent was then rotated counterclockwise to simulate a mean westerly zonal wind. Stratification was chosen to give the same ratios of topographic and dynamical length scales as in the atmosphere, as was the Rossby number based on the ratio of rotation rates. After about ten tank rotation periods, a dominant wavenumber 3 structure with cyclonic eddies in the Ross and Weddell seas and Prydz Bay is observed as an approximately steady state. Flow over the topography is relatively stagnant, with weak anticyclonic circulation. This strongly suggests that these motions in the atmosphere are virtually barotropic. The large cyclonic eddies are forced by flow separation around prominent coastal irregularities such as the Antarctic Peninsula. -from Authors