Shallow gravity flows over the Ekström ice shelf

Wind and temperature profiles measured near the Antarctic Georg von Neumayer Station in January and February 1983 are analysed with respect to situations of low cloud cover. In these situations, shallow inversions develop in the period of low sun elevation. The structure of these inversions in comparison with those in midlatitudes is explained by considering the heat fluxes near the ground, the influence of surface friction over different terrain roughness and for different Coriolis parameters.One effect of stabilisation over the Ekström ice shelf is the development of shallow gravity-influenced flows. The flow dynamics are discussed by means of a scale analysis. The results show that gravity is of considerable influence; however, it will not dominate the other forces. Strictly speaking, the flow is not katabatic for the scale considered. The Froude numbers of the flow approach values similar to those of nocturnal inversions during cooling periods. Thus it seems that the modelling methods for midlatitude stable planetary boundary layers (PBLs) will be successful in explaining antarctic boundary layers as well.