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

Abstract

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