Planetary wave coupling from the stratosphere to the thermosphere during the 2002 Southern Hemisphere pre-stratwarm period
Temperature observations between 20 and 120 km from the SABER instrument on the TIMED spacecraft are used to investigate the nature of planetary wave activity during the 60 days prior to the midwinter stratospheric warming that commenced on 26 September, 2002 in the Southern Hemisphere. The primary wave components consist of eastward-propagating quasi-10-day waves with zonal wave numbers s = 1 and s = 2, and a stationary planetary wave with s = 1. The waves are found to extend from the lower stratosphere to the 100–120 km height region with surprisingly little amplitude attenuation, although wave amplitudes oscillate with altitude like a standing wave pattern. Time evolution of the waves is also addressed with emphasis on 86 km altitude, where temperature observations from three Antarctic stations at Davis (69°S, 78°W), Rothera (68°S, 68°W) and Syowa (69°S, 40°E) are available during the same period. We demonstrate that the temporal evolution of temperature obtained by superposition of the waves derived from SABER measurements accounts for nearly all the temperature variability observed at the longitudes of the three Antarctic stations.