Measurements of katabatic winds between Dome C and Dumont d'Urville

Dumont d'Urville on the Antarctic coast is an area well known for the presence of strong katabatic winds. Since the austral summer 1979/80 a US-French joint experiment has been investigating the katabatic wind in this region. In early 1980 three automatic weather stations (AWS) were installed along a trajectory from Dome Charlie to Dumont d'Urville. Measurements from these stations include air pressure, temperature, wind speed and direction at ground level only. To supplement these data with information regarding the vertical structure and the advective changes in the katabatic flow, two airborne missions were undertaken in November 1980 along a route from Dome Charlie (Dome C) to Dumont d'Urville.In this paper measurements from these two flights are reported and comparisons made with theoretical models of katabatic flow. The data suggest that equilibrium katabatic flow was not established during these two flights. Downslope acceleration of the wind was particularly marked on 20 November, and a hydraulic jump was encountered in the vicinity of Dumont d'Urville. Relative humidity along the trajectory decreased as the coast was approached consistent with the rapid rise in adiabatic temperature. Simultaneously the absolute moisture content of the air increased indicative of net moisture influx. One source of the moisture increase is the evaporation of blowing snow especially in the intense wind region of the coastal slope near Dumont d'Urville.