Enhancement of gravity wave activity observed during a major Southern Hemisphere stratospheric warming by CHAMP/GPS measurements

Abstract

Using temperature profiles measured by CHAMP/GPS occultations we analyzed the gravity wave activity during the major sudden stratospheric warming (SSW) occurred in the Southern Hemisphere (SH) in late winter/spring of 2002, which for the first time split the polar vortex into two parts. The observed temperatures show a rapid poleward moving increase with a maximum of about 25-30 K with respect to the undisturbed winter conditions, and a reversal of the latitudinal gradients at 30 km and below within 15 days (September 15-30). During this time gravity wave energy (potential energy, [iEpi]) became 3 times higher than usual. This enhancement mostly occurred near the edge and outside the cold polar vortex, but not inside the vortex. We discuss the observed event with potential interaction of gravity waves, planetary waves and the mean circulation during the stratospheric warming. Copyright 2004 by the American Geophysical Union.