Arctic Atmosphere Very Clean This Year

Until April 17, scientists from nine countries will examine the Arctic atmosphere, specifically small suspended particles, so-called aerosols, and clouds in order to improve our understanding of the radiation dynamics in the atmosphere, and their impact on climate. Aerosols represent minute airborne substances which, through absorption or reflection of solar radiation have a direct influence on the climate.

In addition, they may have indirect climate effects by acting as crystallisation nuclei in the formation of clouds.  Furthermore, the data collected during this campaign will provide an important contribution to assessment of data from the satellite CALIPSO. Since April 28, 2006, this satellite has been travelling in a polar orbit, observing clouds and aerosols above the Arctic from space.

Measurements will be carried out using research aircraft of the Alfred Wegener Institute (Polar 2), and of the German Aerospace Center (Falcon). Both aircraft are taking off and landing in Longyearbyen, and flights are synchronised with the flight path of the satellite CALIPSO above. In the research town of Ny-Ålesund, 120 kilometres away, researchers support the campaign through ground-based measurements.

First results from recording flights to date indicate that, compared to previous years, the Arctic atmosphere this year is very clean. Nevertheless, at several kilometres altitude, pollution residues from Central and Eastern Europe were detected. The data collected during ASTAR 2007 will aid in the evaluation of CALIPSO measurements, and will improve our understanding of transport of air-masses between the Arctic and temperate latitudes.

The ASTAR project is supported by the German Research Foundation, the Japanese Ministry of Education, Science, Sports, and Culture, the Swedish Polar Research Secretariat, and the French Polar Research Institute IPEV as part of the French-German Arctic Research Base.