Interdiurnal Wind Oscillations in the Antarctic Lower Thermosphere from Meteor Radar Measurements at the Amundsen-Scott and Molodezhnaya Stations

摘要

Interdiurnal wind oscillations in the Antarctic lower thermosphere are analyzed from simultaneous wind measurements in four different directions of sounding conducted at the Amundsen-Scott and Molodezhnaya stations in 1995-1996. The records are unique in continuity (with about 6% gaps on the average) and length (covering the entire annual cycle). The analysis results for the data over the South Pole are compared to those for the wind measurements conducted simultaneously in four different directions of sounding at the Molodezhnaya station in 1990-1991. The wind variability in the Antarctic lower 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 wave propagation: westward in summer, eastward in winter, and a zonally symmetric distribution of wind fluctuations during the transition periods. The sources of the observed wind variability are discussed.