SODAR PERFORMANCE AND PRELIMINARY-RESULTS AFTER ONE-YEAR OF MEASUREMENTS AT ADELIE LAND COAST, EAST ANTARCTICA

Dumont d'Urville, on the Antarctic coast, is an area well known for th e presence of strong katabatic winds blowing from the Antarctic platea u toward the sea almost all year. Since January 1993, a three-axis Dop pler sodar has been operating in this area to investigate the variabil ity of the boundary layer structure and dynamics. In this paper, the c apabilities, behavior and advantages of using this ground-based remote -sensing system in Antarctica are evaluated after one year of measurem ents. This instrument may play an important role in boundary layer stu dies in remote regions where other profiling techniques (e.g., kitoons , slow ascent balloons) are difficult and expensive. All year long, ex cept in summer when the signal-to-noise ratio was dramatically reduced by the noise of a large group of Adelie penguins, reliable measuremen ts were available up to 900 m. The reliability of the vertical wind ve locity has been checked and the influence of the local topography on t he flow pattern has been evaluated. Some preliminary results regarding the statistical analysis of the horizontal and vertical velocities an d an overview of the main physical processes are also shown. The stati stical analysis of the wind speed shows that the wind blows from the 3 0 degrees angular sectors centered at 90 degrees, 150 degrees, 180 deg rees, and 0 degrees. The winds from 90 degrees and 150 degrees constit ute the main local circulation and have, most of the time, the charact eristics of a katabatic flow, whereas the winds blowing from 180 degre es, arising from the surface temperature difference between the sea an d the land, are land breezes. Strong winds coming from the ocean (0 de grees), attributable to the inland penetration of depressions, have be en observed in May, October, and November. Finally, some examples of t he observed thermal structures, as depicted in the facsimile recording , are shown.