SASKOS (2005/2006)

Summer Atmosphere Study at Kohnen Station

The Summer Atmosphere Study at Kohnen Station, Antarctica (SASKOS) was carried out as a 2.5 months measurement program in austral summer 2005/2006 at the drilling site of the European Project for Ice Coring in Antarctica (EPICA) on the plateau of Dronning Maud Land (Fig. 1).

To study the influence of the local wind regime on the formation of small-scale accumulation patterns like snow dunes (Fig. 2), synoptic observations were combined with a glaciological field program. At the same time, forecasts of the Antarctic Mesoscale Prediction System and satellite images were used to study the large-scale and regional synoptic situation.

Analyses of shallow cores obtained at the EPICA drilling site Kohnen Station (75°00’ S, 00°04’ E; 2892 m a.s.l.) reveal the presence of conserved snow dunes in the firn. The snow dunes reduce air circulation due to their high density. If the layering propagates downwards to the firn-ice transition, the occurrence of snow dunes could affect the air entrapment. The

high-density layers serve as a lid, isolating the air from the atmosphere in lower depths than is expected in non-stratified firn. It follows that the age difference between enclosed air and the surrounding ice at a location like Kohnen Station becomes smaller than at sites with similar snow accumulation but without dune formation.