A STATISTICAL-ANALYSIS OF WIND IN TERRA-NOVA-BAY, ANTARCTICA, FOR THE AUSTRAL SUMMERS 1988 AND 1989

A statistical analysis of wind frequencies has been done analyzing Sodar and Automatic Weather Stations (AWS) data recorded during two successive summer campaigns in Terra Nova Bay area, Antarctica. A preliminary analysis performed using AWS data for the same periods showed that no particular differences occurred between the two summers. This encouraged a comparison between sodar data at the two sites and the AWS as they would have been recorded at the same time. The local circulation is largely dominated by the katabatic winds originating by radiative cooling of near-surface air along the slopes of Reeves (270 degrees) and Priestley (330 degrees) glaciers. The surface wind frequencies showed a strong dependence on the station location confirming the preminent role of the orography on the air how. Sodar data evidenced that a considerable variation of wind intensity and direction may occur in the upper levels and highlighted some aspects of the three-dimensional air motions. The contemporary analysis of the sodar profiles and AWS surface measurements allowed us to bring out some peculiarities of the local summer circulation related to the variation of the relative buoyancy of the two flows blowing from the Priestley and Reeves glaciers. During the summer, contrary to the winter, the airstream issuing from the Priestley does not cross the Northern Foothills and flows into the Nansen Ice Sheet at the confluence of Reeves and Priestley glaciers. Consequently, at the coastal site stations, the observed air flow is attributable to the Reeves glacier, which is more buoyant and capable, because of the greater air mass involved and of the sufficient speed to cross the Northern Foothills. Moreover, it has been shown how the Northern Foothills prevent barrier winds, running parallel to Transantarctic Mountains from reaching the coastal site where the Italian base is located. On the contrary a peak for barrier wind was observed when sodar was on Nansen Ice Sheet.