Long range transport of air pollutants in Europe and acid precipitation in Norway

Observations show that pollutants from large emission sources may cause significant air concentrations 500 to 1000 mi away. Very acid precipitation occurs in such periods. The scavenging is often intensified by the topography. Case studies will be presented with special emphasis on acid precipitation in Scandinavia. Large scale dispersion models have been developed recently in order to estimate the long range transport of air pollutants. The models take into account chemical transformations as well as deposition of pollutants. The calculations will be compared with observations from airplanes and surface stations. A simple model has been integrated over a long period of time in order to derive the best value for the decay rate of SO₂. This best value is based on a day-by-day comparison with surface observations.