Observations of vertical winds in the thermosphere with a fabry-perot doppler imager at syowa station, Antarctica

In order to study the changes of thermospheric vertical winds associated with auroral activity, observations with a Fabry-Perot Doppler Imaging System (FPDIS) were carried out a Syowa station, Antarctica (66.4 deg. MLAT) on 37 nights from April to October in 1996. Vertical wind velocities in the lower and upper thermosphere were estimated from Doppler shifts of two auroral emission lines, OI 557.7-nn and OI 630-nm with peak emission heights at ~120 km and ~250 km, respectively. In this paper, it was found that for two nights the oscillations of vertical winds occurred in the lower and upper thermosphere, while auroral arcs existed mostly poleward of Syowa station. The period of the oscillations was 1-2 hours and the maximum amplitude was ~40 m/s. It is inferred that the oscillations of vertical winds are due to equatorial propagating atmospheric gravity waves which are originally generated around auroral arcs.