On the Role of Antarctic Katabatic Winds in Forcing Large-Scale Tropospheric Motions

Abstract

Katabatic winds are a dominant feature of the lower atmosphere over Antarctica. The radial diffluence displayed by the drainage flows implies that a continental-scale subsidence is present over Antarctica. From mass continuity considerations, a thermally direct meridional circulation must become established. The upper-level convergence above the Antarctic continent acting to feed the katabatic circulation generates cyclonic vorticity in the middle and upper troposphere. Model simulations show that a robust circumpolar circulation becomes established within a time scale of about a week. The adverse horizontal pressure gradients in the upper atmosphere result in a gradual decay of the low-level katabatic circulation. The katabatic wind regime appears to be an important forcing mechanism for the circumpolar vortex about the periphery of the Antarctic continent.