Modeling the Southern Hemisphere winter circulation using stratospheric gravity wave information based on GNSS radio occultations

DE LA TORRE, A.; JACOBI, C.; LILIENTHAL, F.; SCHMIDT, T.; ALEXANDER, P.

Graz

Congreso; Occultations for Probing Atmosphere and Climate 6; 2016

A mechanistic global circulation model is used tosimulate the meso­spheric and lower thermospheric circulation during Australwinter. The model includes a gravity wave (GW) parameterization that isinitiated by prescribed GW parameters in the troposphere. In standardconfiguration, these waves are described by a zonal mean dis­tribution withlarge amplitudes in the winter hemisphere and small ones in summer. Here wereplace this distribution by a more realistic one, which is based on observa­tionsof potential GW energy using GPS radio occultations, but which is normalized tothe same global mean amplitude. The model experiments show that this newgravity wave distribution, originating from enhanced GW activity east of theAndes, around the Antarctic Peninsula and the Transantarctic Montains, leads tothe forcing of stationary planetary waves in the stratosphere, and a weakerzonal wind jet in the mesosphere and warming near the mesopause above the jet.