The influence of north American anthropogenic sulphur emissions over western Europe

Abstract

A 3-dimensional Eulerian model is used to evaluate the influence of North American anthropogenic sulphur emissions over the western coast of Europe. Transport of sulphur across the North Atlantic ocean is simulated on the basis of the actual meteorology for 4 different months during 1982 and 1983. Results show large regional variations and indicate that the relative importance of North American emissions is largest over north western Europe. The North American contribution to pollution levels over western Europe is shown to occur mainly as wet deposition. Maximum wet deposition of North American origin over north western Europe is predicted for January 1983. On average over the four simulated months, the wet deposition of North American origin is estimated to be 2 mg S m^-2 month^-1 which represents 10% of the calculated total deposition over western Europe. The influence of North American sulphur on the air concentrations over the west coast of Europe is relatively larger at higher levels in the atmosphere. At ground level, the North American contribution to sulphate in air represents only 2.5% of the averaged total calculated, but it ascends to 50% at 5000 m. Maximum contributions to the sulphate concentrations in air over western Europe are estimated to occur during July 1983.