Dynamics of the tower thermosphere over South Pole from meteor radar wind measurements

A meteor radar was operated at Amundsen-Scott Station, South Pole, from Jan uary 19, 1995 through January 26, 1996 and from November 21, 1996 through J anuary 27, 1997. Hourly wind measurements were obtained nearly continuously over these time periods, at an approximate altitude of 95 km and at about 2 degrees latitude from South Pole along the longitude meridians 0 degrees, 90 degrees E, 90 degrees W, and 180 degrees. The scientific advances achie ved to date through analyses of these data are presented, including updates to several of our previously published works. The findings addressed herei n include the following: (1) Strong divergences of zonal-mean meridional wi nds occasionally occur over South Pole, implying extreme vertical winds; (2 ) The monthly mean zonally asymmetric (zonal wavenumber s = I) wind compone nt varies during the year in a manner consistent with migration of the cent er of the polar vortex with respect to the geographic (rotational) pole; (3 ) Strong (>15 m/s) westward-propagating migrating diurnal (s = 1) and non-m igrating semidiurnal (s = 1) oscillations exist except during winter months ; (4) Long-period (similar to 2-10 days) waves exist during winter months w hich are primarily eastward-propagating; (5) Intradiurnal (periods similar to 6-11.5 hours) westward-propagating oscillations exist, which are thought to be gravitational normal modes, or "Lamb" waves.