Simultaneous Measurements of Antarctic Mesospheric Gravity Waves by Meteor Radar and Lidar

Abstract

Simultaneous measurements of high-latitude upper mesospheric gravity waves by a 50MHz meteor radar and a dye lidar were made at Syowa Station, Antarctica, in 1985. The radar measured nearly north-south components of neutral wind velocities at altitudes of 80-100km and at slant ranges of 110-600km from Syowa Station, while the lidar measured the sodium density profile and sodium abundance at the same altitudes at the zenith of Syowa Station. From measurements on six nights, it is found that short-period (1-2 hours) and long-period (≥2 hours) perturbations of the wind velocity due to gravity waves are well manifested in the sodium abundance and sodium density perturbations, thus suggesting that the response of the neutral winds to gravity waves is fundamentally consistent with the sodium layer response. From a case study, it is demonstrated that during a mediumscale auroral substorm, a strong equatorward wind attaining a maximum of 60m/s appeared in accord with a gradual decrease in sodium abundance. A mechanism explaining this causal relation is unknown.