Long term regional patterns and transfrontier exchanges of airborne sulfur pollution in Europe

Abstract

This paper reports on progress to date of an ongoing effort to develop, evaluate and apply a European Regional Model of Air Pollution (EURMAP). This model is capable of calculating longterm (monthly, seasonal and/or annual) averages of the contributions from SO 2 in individual emittor countries to SO 2 and SO 4 2− concentrations, dry deposition and wet deposition in receptor countries. The model covers all of western and central Europe, a geographical area 2100 km × 2250 km in size. A trajectory-type approach is used, which involves the tracking of pollutant ‘puffs’ released from each emissions cell in an extensive 32 × 36 grid. Meteorological data in the form of wind and precipitation values from some 45 upper-air and 535 surface stations are input at 6-hourly intervals for use in the calculations of puff transport and wet deposition. A wet deposition coefficient is used that depends upon precipitation rate. The preliminary model has been used to calculate annualized as well as monthly mean maps for January, April, July and October 1973 of SO 2 and SO 4 2− concentration, dry deposition and wet deposition patterns resulting from SO 2 emissions in 13 countries in western and central Europe. The dry and wet deposition patterns are presented, along with values of calculated international exchanges of SO 2 and SO 4 2− wet and dry deposition among these various countries. The EURMAP results are compared with those from Fisher's (1975) model and the LRTAP model (Ottar, 1978; OECD, 1977). In many (but not all) respects the results from the three models are similar. The possible reasons for the differences revealed by this comparison are examined.