The large-scale dynamics of the mesosphere-lower thermosphere during the Southern Hemisphere stratospheric warming of 2002

Abstract

An unprecedented major stratospheric warming occurred in the Antarctic winter of 2002. We present measurements of winds in the mesosphere-lower thermosphere (MLT) made with MF radars located at Davis (69°S, 78°E), Syowa (69°S, 40°E) and Rothera (68°S, 68°W). The mesospheric wind field in 2002 was found to be considerably different to other years due to increased planetary wave activity throughout the winter. Zonal winds were weaker than usual during the 2002 winter and also during the transition to the summer circulation. The MLT zonal winds showed a reversal about one week earlier than the stratospheric reversal associated with the warming. Meridional winds showed oscillations consistent with the presence of traveling wave-1 planetary waves with periods ∼14 days. The results are compared with similar mesospheric observations made during northern hemisphere stratospheric warmings. Some similarities between hemispheres were found, notably that the reversal in the mesospheric winds precedes the warming events.