NILU’s atmospheric research in Ny-Ålesund serves three main purposes: Characterisation of the clean atmosphere and atmospheric changes. Investigations of atmospheric transport of pollutants into the Arctic. Studies of atmospheric processes and phenomena in the Arctic.
The Arctic is an interesting area for observations relevant to the cycling of carbon dioxide and other gases which are of concern in connection with climate change. It is also subject to influx of polluted air masses, particularly in the winter. This influx is caused by strong cyclonic activity in the North Atlantic and the Norwegian Sea in late winter and spring, and by limited photochemical activity and deposition as the air travels over snow-covered areas with almost no radiation. Marked changes in the photochemical activity and in the atmospheric conditions take place immediately after the Arctic sunrise in March-April.
The research facilities at Ny-Ålesund, and in particular the research station at the Zeppelin Mountain, are excellent for atmospheric research. This platform has been built at a mountain ridge south of Ny-Ålesund, 475 m above sea level, in order to minimise any effects of emissions from the local settlement and infrastructure. At 79° north, Ny-Ålesund is easily accessible by commercial flights to Longyearbyen, and by small aircraft from Longyearbyen to Ny-Ålesund. The infrastructure at Ny-Ålesund is well developed with respect to accommodation and technical facilities.
The Arctic atmosphere is part of the global atmospheric circulation. However, unlike in the Antarctic, strong meridional circulation extends into and even across the polar cap. This has advantages as well as disadvantages for atmospheric research. However, it is possible to observe both the effect of anthropogenic releases as well as the slow changes of atmospheric composition which is caused by the total emissions of long-lived atmospheric species such as carbon dioxide, methane, nitrous oxide, chlorofluorocarbons (CFCs) and related chemical species. In the troposphere, ozone is also a greenhouse gas, and Ny-Ålesund is a particularly suitable location for investigations of ozone and the precursors of tropospheric ozone formation, viz. volatile organic compounds and nitrogen oxides.
Cooling by atmospheric aerosol is another important topic in the climatic change issue. Arctic Haze is caused by influx of sulphate aerosols from the Eurasian continent in late winter and spring, and is generally confined to the lowest 800-1000 m of the Arctic atmosphere. Elevated haze layers may contain both anthropogenic and natural aerosols from volcanoes as well as from deserts. These can be observed by optical methods, or by sampling from aircraft.
Atmospheric transport of pollutants into the Arctic Not only Arctic Haze is introduced to the Arctic by atmospheric transport. Needless to say, ozone and its chemical precursors, as well as their degradation products are brought in by the same winds as sulphur dioxide and sulphate aerosols. The transport pattern varies according to season and to the meteorological situation, and the events with Arctic Haze and other pollutants alternate with periods in which the air masses are extremely clean.
Of particular concern in the Arctic are compounds that may influence the Arctic directly. Within this group, certain persistent organic compounds are particularly important because of their persistence and accumulation in Arctic food-chains. These compounds include both pesticides such as DDT, Toxaphene and Lindane, and industrial chemicals such as PCB’s and chlorinated naphthalenes. These compounds are carried by the air and taken up by the ocean or other water bodies, and biologically enriched because of their high solubility in lipids. NILU is presently monitoring a wide range of persistent organic pollutants (POPs) as well as heavy metals in air at Ny-Ålesund.
Arctic `ozone holes` The processes which since about 1980 are responsible for the occurrence of the so-called ozone hole in the Antarctic are also active in the Arctic. Stratospheric ozone depletion is known to be caused by chlorine originating from CFCs and related chemicals as well as by bromine from industrially produced Halons. It occurs in connection with the formation of cold, stratospheric clouds. The depletion is therefore highly dependent on the meteorological circulation pattern, particularly with the formation of isolated air packets characterised by the potential vorticity in the upper atmosphere.
NILU has several instruments in Ny-Ålesund which measure both the thickness of the ozone layer, as well as some of the chemical species which actually destroy ozone. The UV radiation reaching ground level is also measured.
Another ozone `hole` of a quite different kind has been studied in the Arctic for about ten years. Each spring episodes of extremely low ozone concentrations near the ground have been detected at Ny-Ålesund as well as other Arctic stations. This is not an environmental problem, but the phenomenon has been studied in detail during the last few years, as it is believed to impact the ozone budget on a large scale.
Scientists from many nations are doing atmospheric research in Ny-Ålesund. NILU has a close collaboration with the group from the Meteorological Institute at the University of Stockholm, Sweden, which measures CO2 and other species at the Zeppelin station, as well as with German, Japanese and Italian scientists who have their own atmospheric research facilities in Ny-Ålesund. In addition NILU often arranges research campaigns in collaboration with scientists from all over Europe as well as from the United States.
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