A re-examination of the winds of Adélie Land, Antarctica

Records of the surface wind at the coast of Adélie Land, Antarctica between 140°E and 144°E show an annual mean wind speed of approximately 20 m s-1. The intensity of this wind regime remains unsurpassed for stations at sea level. The lowlevel winds are thought to be primarily katabatic, having their origin over the continental interior. Surface winds display an extremely high directional constancy value of near 1.0, implying that the air flow is essentially unidirectional. Wind speeds show a seasonal bias. The intensity of the mean winds during the winter period from June through August is 60 per cent stronger than those observed during the short summertime period of December through February. Confluent channelling of the drainage flows off the ice sheets upwind from Adélie Land has been proposed as the reason for the intense wind conditions at this section of coastal Antarctica. Streamline convergence in the interior of the continent ensures an ample supply of negatively buoyant air that enables the coastal wind regime to be so persistent. Analyses of the original hourly data series collected by Mawson’s party at Cape Denison and subsequent records from automatic weather stations along Adélie Land have been completed. Gridded model output from real-time mesoscale simulations of the Antarctic atmosphere and high southern latitudes using a modified version of the Fifth-generation Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model (Polar MM5) from the one-year period November 2001 to October 2002 have also been analysed to investigate the mean structure and extent of the strong wind zone. Detailed simulations with Polar MM5 have been conducted during April 2002 to investigate the modulation of the Adélie Land winds due to cyclones to the north of the coastline. Some thoughts as to the uniqueness of the Adélie Land winds are offered.