Thursday, 12 June 2008: 12:15 PM
Aula Magna Höger (Aula Magna)
Observational data from three automated weather stations with drastically different latitude and elevation in Eastern Antarctica were compared to determine the dependence of surface-layer wind, temperature, and stability on latitude and elevation. The results revealed that at lower elevations, near surface winds are katabatic which blow predominantly down the topographic slope. In contrast, over the top of the plateau, the wind direction distribution is very broad suggesting that the cold air that build up over the top of East Antarctic plateau spread out and flow down the slope in different directions. There is a clear diurnal temperature oscillation at all three stations with similar phase but slightly different amplitude. The wind speeds and the vertical temperature gradients at the two lower elevation stations also exhibit a diurnal oscillation. The coincidence between the maximum near-surface wind and the strongest instability near local noon suggests downward momentum transfer by turbulence as the mechanism for diurnal wind oscillation at these sites. On top of the plateau, there is little variation in vertical gradient of temperature and the near-surface atmosphere is mostly stable. Consequently, no clear connection between diurnal variation of wind speed and temperature gradients is found.
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