A dynamical explanation of the topographically bound easterly low-level jet surrounding antarctica

Abstract

This study investigates the topographically bound easterly low-level jet surrounding Antarctica. This jet is modeled as a balanced flow that satisfies the potential vorticity invertibility principle, based on local linear balance in spherical coordinates and expressed in isentropic coordinates. In this way, this easterly low-level jet is shown to be the balanced flow associated with the topography of the Antarctic plateau, moderated by a shallow potential vorticity anomaly atop the plateau produced by radiative cooling. The dynamical connection of the jet with katabatic winds can be understood through the meridional circulation equation. Model results based on the simple theoretical arguments developed here are found to be consistent with high-resolution reanalysis data from the European Centre for Medium-Range Weather Forecasts for the 2008–2010 period.