Strong-wind events and their influence on the formation of snow dunes: Observations from Kohnen station, Dronning Maud Land, Antarctica

Analyses of shallow cores obtained at the European Project for Ice Coring in Antarctica (EPICA) drilling site Kohnen station (75°00' S, 00°04' E; 2892 ma.s.l.) on the plateau of Dronning Maud Land reveal the presence of conserved snow dunes in the firn. In situ observations during three dune formation events in the 2005/06 austral summer at Kohnen station show that these periods were characterized by a phase of 2 or 3 days with snowdrift prior to dune formation which only occurred during high wind speeds of >10ms ^-1 at 2m height caused by the influence of a low-pressure system. The dune surface coverage after a formation event varied between 5% and 15%, with a typical dune size of (4±2)m×(8±3) m, a maximum height of 0.2±0.1m and a periodicity length of about 30 m. The mean density within a snow dune varied between 380 and 500 kgm^-3, whereas the mean density at the surrounding surface was 330±5kgm^-3. The firn cores covering a time-span of 22±2 years reveal that approximately three to eight events per year occurred, during which snow dunes had been formed and were preserved in the firn.