Mesospheric mean winds and tides observed by the Imaging Doppler Interferometer (IDI) at Halley, Antarctica

Abstract

This paper describes the first ever mesospheric wind observations from Halley, Antarctica, over a full year. The recent implementation of an Imaging Doppler Interferometer at Halley is providing a new, high quality and continuous dataset to investigate the dynamics of the Antarctic mesosphere. The mean winds show clear seasonal variations, with reversals in both zonal and meridional components near the equinoxes. The dominant tidal modes have periods of 12 h and 24 h but with significant variations in amplitude during the year. Waves with longer periods are also apparent at certain times of year. The seasonal variations and amplitudes of the winds and tides are compared with other high-latitude sites in the southern and northern hemispheres. It is found that the overall pattern of winds at Halley is broadly similar to that seen at similar geographic latitudes, but with noticeable differences which may be related to it being a southern hemisphere site.