Mean Meridional Circulation in the Southern Hemisphere Stratosphere Based on Satellite Information

Abstract

Atmospheric structure derived from satellite, multi-channel radiance data is used to calculate zonally- averaged vertical motions in the wintertime stratosphere of both hemispheres using a heat budget approach. The Northern Hemisphere calculations based on the satellite data are shown to compare favorably with a computation carried out with conventional data, and with results of previous studies. The mean Southern Hemisphere pattern for the month of July 1969 indicates a high-latitude cell with the axis of sinking motion at approximately 50°S, while the rising motion is centered at 70°S. Thus the antarctic stratosphere jet stream is associated with an indirect cell. Two individual 10-day periods from July 1969 are examined to compare the mean meridional circulation and eddy heat flux patterns in the Southern Hemisphere during a minor midwinter warming and during a quiet period. Large eddy fluxes at 60°S and a strong indirect cell in the meridional circulation are associated with the minor warming. During the quiet period eddy fluxes at 60°S are relatively small and the mean meridional circulation appears to develop an additional cell in very high latitudes with sinking motion over the South Pole.