Sodar observations of the antarctic boundary layer in a deglaciated area: Preliminary results

A single-axis sodar system, with off-line Doppler analysis, has been operated in the month of January 1987 at the Italian Antarctic base near Terra Nova Bay. The instrument was installed in complex terrain at a distance of approximately 1 km from the shore-line. During the campaign the area around the station, for a width of about (2÷3) km from the shore, was completely deglaciated and exposed to periods of direct solar irradiation. The measurements were carried out almost continuously with the antenna pointing to the zenith or at zenith angles of 20° and 30° in the NE direction. From a preliminary analysis of the data, the main phenomena observed were as follows:a) Very intense convection during periods of insolation with vertical velocities up to 4 ms-1. b) Evidence of layering and Kelvin-Helmholtz instabilities. c) Strong subsidence.