Observations of the near-surface wind and temperature structures in East Antarctica

The first multi-year surface meteorological observations from Dome A, the highest ice feature in the entire Antarctica continent, are analyzed to understand the climatology of near-surface wind, temperature and stability at this site and the differences from the climatology observed at lower elevation/latitude locations in Eastern Antarctica. Unlike the surface winds at lower elevation sites where moderate to strong northeasterly winds prevail, the summertime surface winds at Dome A are generally very weak (with a mean of 3 m s-1) and variable in direction. Similar to stations at lower latitude/elevation, a diurnal oscillation of surface temperature and stability occurs at Dome A. However, the near-surface atmosphere at Dome A is stable all year long due to small solar insolation at the very high latitude (80.37 oS), whereas stations at lower latitudes can develop an unstable boundary layer in summer. The downward momentum transfer by turbulent mixing in the summertime unstable boundary layer lead to a diurnal oscillation in surface wind speed at lower latitude/elevation stations that is absent from the observations at Dome A. Wavelet analysis of near-surface stability revealed that besides the strong diurnal signal, the near-surface stability also exhibits annual, semi-annual, and inter-seasonal (peaks around 50 days) oscillations at all locations. These oscillations in near-surface stability are linked to the same peaks in the 500-hPa geopotential height spectra and therefore are believed to be caused by variations of synoptic conditions.