The Topographically Bound Low-Level Easterly Jet Surrounding Antarctica

This study investigates the topographically bound low-level, easterly jet surrounding Antarctica. This jet is modeled as a balanced flow that obeys the potential vorticity invertibility principle. This invertibility principle is expressed in isentropic coordinates, using local linear balance as the balance condition in the spherical coordinate formulation of the elliptic problem. In this way, the lowlevel easterly flow around Antarctica can be attributed to the fact that radiative cooling over the Antarctic plateau results in the bending of isentropic surfaces sharply upward at the edge of the plateau and in the production of a shallow potential vorticity anomaly just above the plateau. 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 ECMWF reanalysis data for the 2008–2010 period. To be submitted to Journal of the Atmospheric Sciences Corresponding author address: Scott R. Fulton, Department of Mathematics, Clarkson University, Potsdam, NY, USA. Email: [email protected]