Climatological variability of sulfur depositions in Europe

Abstract

The climatological variability in historical and projected S deposition levels for Europe have been simulated using a simple source-receptor model that runs on a personal computer (RCDM) using an extended period of wind and precipitation data. The variability in historical temperature and precipitation data has been analyzed to assess the representativeness of the limited meteorological period used in the EMEP model (1978–1982). A match-up between 40 selected EMEP monitoring sites and the closest climatological station showed the 5-yr average for the EMEP period (1978–1982) and the 35-yr precipitation amounts in generally good agreement for the majority of sites. Comparisons between the RCDM model simulations using the IIASA base 1980 SO₂ emissions and the 1978–1982 average precipitation amounts showed the model predictions were generally within a factor of two of the EMEP concentrations and depositions at 40 selected sites. The sensitivity of model evaluation results to ‘free parameter’ tuning and the appropriateness of the resulting ‘free parameters’ requires more analysis. The total S depositions at the IIASA receptors predicted by the RCDM model under base year 1980 emissions showed very small differences between the predicted total S depositions for the 1978–1982 EMEP period and the 1951–1985 normal period. The long-period variability in annual total S depositions simulated by the RCDM with constant emissions showed the largest fluctuations in the mid-1970s and showed that the means and C.V.s were not significantly different between the time periods of interest. It is recommended that additional source areas for the Soviet Union be added to the model and the sensitivity to country emission and area centroid locations be explored.