Interdiurnal wind oscillations in the Antarctic lower thermosphere from meteor radar measurements at the Amundsen-Scott and Molodezhnaya stations

Interdiurnal wind oscillations in the Antarctic lower thermosphere are anal yzed from simultaneous wind measurements in four different directions of so unding conducted at the Amundsen-Scott and Molodezhnaya stations in 1995-19 96. The records are unique in continuity (with about 6% gaps on the average ) and length (covering the entire annual cycle). The analysis results for t he data over the South Pole are compared to those for the wind measurements conducted simultaneously in four different directions of sounding at the M olodezhnaya station in 1990-1991. The wind variability in the Antarctic low er thermosphere is shown to have a distinct seasonal cycle, in which summer and winter seasons and periods of transient circulation can be identified. Each of the seasons is characterized by the intensity of oscillations (the weakest ones are observed in summer) and by the prevailing direction of wa ve propagation: westward in summer, eastward in winter, and a zonally symme tric distribution of wind fluctuations during the transition periods. The s ources of the observed wind variability are discussed.