The influence of baroclinicity and stability on the wind and temperature conditions at the Georg von Neumayer Antarctic station

Abstract

The situation that arises when a stably stratified layer of air exists over a large inclined surface is examined using a resistance law formulation for baroclinic conditions. The dependence of the surface wind direction on the surface Rossby number, the stability parameter S and the angle between the geostrophic wind direction and the vector of largest inclination is obtained. For slope angles typical for the coastal areas of eastern Antarctica, the surface wind direction is mainly determined by the static stability of the air mass through its thermal wind effects, while its stabilizing effect on turbulent motion is less important for boundary layer wind veering. Consequently a simpler analytic formula can be derived which is able to describe the features of the flow direction with respect to the free atmospheric geostrophic wind and the temperature deficit within the boundary layer. Synoptic data from the Georg von Neumayer Antarctic Station obtained in 1983 are discussed using the theoretical results. The comparison of theory and observations clearly suggests that the observed relationships between the wind speed, the wind direction and the temperature can only be explained when a strong baroclinicity at the antarctic coast is taken into account.