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

This paper describes the first ever mesospheric wind observations from Hall ey, Antarctica, over a full year. The recent implementation of an Imaging D oppler Interferometer at Halley is providing a new, high quality and contin uous dataset to investigate the dynamics of the Antarctic mesosphere. The m ean winds show clear seasonal variations, with reversals in both zonal and meridional components near the equinoxes. The dominant tidal modes have per iods of 12 h and 24 h but with significant variations in amplitude during t he year. Waves with longer periods are also apparent at certain times of ye ar. The seasonal variations and amplitudes of the winds and tides are compa red with other high-latitude sites in the southern and northern hemispheres . It is found that the overall pattern of winds at Halley is broadly simila r to that seen at similar geographic latitudes, but with noticeable differe nces which may be related to it being a southern hemisphere site. (C) 1999 Elsevier Science Ltd. All rights reserved.