Characterization of Atmospheric Ekman Spirals at Dome C, Antarctica

We use wind speed and temperature measurements taken along a 45-m meteorological tower located at Dome C, Antarctica (75. 06 ^∘S , 123. 19 ^∘E) to highlight and characterize the Ekman spiral. Firstly, temperature records reveal that the atmospheric boundary layer at Dome C is stable during winter and summer nights (i.e., > 85 % of the time). The wind vector, in both speed and direction, also shows a strong dependence with elevation. An Ekman model was then fitted to the measurements. Results show that the wind vector follows the Ekman spiral structure for more than 20 % of the year (2009). Most Ekman spirals have been detected during summer nights, that is, when the boundary layer is slightly stratified. During these episodes, the boundary-layer height ranged from 25 to 100 m, the eddy viscosity from 0.004 to 0.06m2s-1, and the Richardson number from zero to 1.6.