Summer 2009 thermal and bioclimatic conditions in Ebba Valley, central Spitsbergen

Summer 2009 thermal and bioclimatic conditions in Ebba Valley, central Spitsbergen The thermal, anemometric and bioclimatic conditions on the topoclimatic scale were investigated in the summer season in the EbbaValley region in central Spitsbergen. Eight measurement sites, representing different ecosystems and different types of active surfaces typical of Spitsbergen, were chosen and automatic, hourly recorded, measurements were performed at the sites between 11 and 25 of July 2009. The analysis of the spatial distribution of the air temperature and thewind-chill temperature, both for the dayswith radiation and non-radiation weather, indicates that the most favorable regions in the interior of Spitsbergen are those situated in the shielded central parts of the valleys and in the lower parts of the slopes with southern exposure. The thermal and wind conditions are definitely less favorable at the tops of elevations and on the glacier. Large differences between the air temperature and the wind-chill temperature were noted, particularly during the unfavorable non-radiation weather, on the glacier and on open peaks due to a large horizontal and vertical wind-chill temperature gradient. The thermal inversions observed in the Ebba Valley in July 2009 were not of the typical, glacier katabatic wind origin. They appeared during the western air circulation, which brings advection of cooled air from above the cold waters of Petunia Bay. The cold air penetrates into the valley and pushes upwards themass of warmer air in the valley, creating a rather thin inversion layer, whose upper edge is marked with thin Stratus clouds.