COMPLEXITY OF THE WIND-FIELD AS OBSERVED BY A SODAR SYSTEM AND BY AUTOMATIC WEATHER STATIONS ON THE NANSEN ICE-SHEET, ANTARCTICA, DURING SUMMER 1988-89 - 2 CASE-STUDIES

In the Antarctic boundary layer, some phenomena appear to be particularly enhanced with respect to those at midlatitudes. Thermal stratifications are present almost all year and can substain drainage flows of different types. Several episodes of flows with different potential temperature and consequently with different buoyancy were observed on the Nansen Ice Sheet by a sodar. Two case studies are presented in which a comparison with the data of the automatic weather stations located on the Reeves and the Priestley glaciers as well on the Nansen Ice Sheet have been used. As a main result, we saw that during the summer time, the flow from the Reeves glacier may superimpose the one from the Priestley, in contrast with the current opinion based on the automatic weather station measurements averaged over the entire year. Also, an episode of barrier-katabatic flow interaction is shown in which the first is negatively buoyant in comparison with the second. Since the wind profile frequently showed a great variability with height, the importance of using remote sensing sensors in studies that realistically want to model the dynamics of the Antarctic boundary layer has been emphasized.