Slope Winds and the Axisymmetric Circulation over Antarctica

Abstract

An axisymmetric model of the flow over Antarctica is used to study the circulation induced by cooling of the air at the slopes of the continent. It is found that the resulting circulation with southeasterly surface winds and westerlies in the free troposphere agrees qualitatively quite well with the observed circulation. The profiles of wind and temperature obtained above the slope are compared to the results from a simple one-dimensional model of flow over sloping terrain. The agreement is quite good near the surface but not at upper levels. The reasons for this discrepancy are discussed. It is found that the two-dimensional flow does not settle down to a satisfactory steady state. It is argued that the surface easterlies at the slopes of Antarctica provide a source of westerly angular momentum. In the atmosphere, three-dimensional eddies can export momentum to lower latitudes, whereas the flow in the model cannot dispose of the momentum. This points to the limitations of the two-dimensional approach.