Climate researchers study haze over the Arctic

An international team of scientists is currently investigating a haze layer that spreads over the Arctic each spring. This layer of air contains aerosols whose expansion in the otherwise clean Arctic atmosphere leads to a level of pollution that usually occurs only over industrial areas. One of the most important questions arising is whether or not this might have direct or indirect effects on the climate. Aerosols are air-suspended particles that directly influence climate through absorption or reflection of solar radiation. In addition, they can act as crystallization nuclei and cause formation of clouds, thus influencing climate indirectly. By spring 2000, scientists of the Alfred Wegener Institute for Polar and Marine Research had already discovered that, during summer, concentrations of the heavy metals lead and cadmium in the Arctic haze were elevated three- to fivefold compared to clear polar air. The concentration in spring is comparable to that in central Europe, although there are few anthropogenic sources of aerosols in the Arctic. The pollution of the Arctic atmosphere evidently originates in remote industrial regions. Aircraft measurements Under the direction of the Alfred Wegener Institute and the Japanese National Institute for Polar Research (NIPR), an international consortium is using various research stations to investigate the Arctic haze phenomenon. The goal of the current project ASTAR 2004 (Arctic Study of Tropospheric Aeorosol, Clouds and Radiation) is the exact recording of this air layer during the transition from Arctic spring to Arctic summer. The measurements are only possible through the assistance of two polar aircraft, “Polar 2” and “Polar 4”, of the Alfred Wegener Institute, which are operated from Longyearbyen on Spitsbergen. The aircraft service is operated by the "Deutsche Zentrum für Luft- und Raumfahrt" ('German Aerospace Centre DLR'). "Optimare Sensorsysteme AG Bremerhaven" is responsible for maintenance of the scientific systems. The aircraft are equipped with a multitude of instruments that determine the properties of aerosols as well as their interaction with cloud particles. In “Polar 4”, measurement systems to determine optical, microphysical and chemical aerosol concentrations have been installed. In “Polar 2”, systems for the identification of microphysical properties of cloud particles have been installed, as well as the new light radar system (AMALI) for remote sensing of the aerosol distribution in the lower troposphere. Further analyses, including mathematical modelling, will be carried out later at the Alfred Wegener Institute. Network of ground level measurements and satellite observations In order to be able to assess the complexity of Arctic haze, measurements similar to the flight recordings in Ny-Ålesund on Spitsbergen (home base of the German-French Arctic station, the Japanese station and the Norwegian-Swedish mountain station) will be made at ground level. Additional measurements will be conducted at the Polish polar station in Hornsund on Spitsbergen, at the Finnish station in Pallas Sodankylae (Finland), as well as in Point Barrow, Alaska (USA). Furthermore, the data will be used to complement NASA and ENVISAT satellite projects. These projects support ASTAR scientists, in turn, by provision of current regional satellite data. This year's six-week measurement expedition is part of a series that has been ongoing since 2000. A further Arctic aircraft expedition is planned for March/April of next year. The ASTAR project is supported by the German Research Council, the Japanese Ministry for Education, Science, Sports and Culture, the Swedish Polar Research Secretariat and the French Polar Institute Paul Emile Victor ([IPEV] within the framework of the joint German/French Arctic Station).

The expedition will end June 15, 2004.

On June 17, the AWI aircraft “Polar 2” and “Polar 4” will return to Bremerhaven.

Bremerhaven, May 19, 2004