AND CONCLUSIONS OF THE WARSAW II MEETING ON ATMOSPHERIC COMPUTATIONS TO ASSESS ACIDIFICATION IN EUROPE JOSEPH ALCAMO and JERZY BARTNICKI International Institute for Applied Systems Analysis Schlossplatz 1, A-2361 Laxenburg, Austria (Received June 1, 1988; revised June 20, 1988) Abstract. Three topics are discussed in this report: sensitivity/uncertainty analysis of long range transport models, the interface between atmospheric models of different scales, and linkage between atmospheric and ecological models. In separate analyses oflong range transport models, it was found that uncertainty of annual S deposition was mostly affected by uncertainty of wind velocity, mixing height and wet deposition parameterization. Uncertain parameters collectively caused S deposition errors of around 10-25% (coefficient of variation) in the models examined. The effect of interannual meteorological variability on computed annual S deposition was relatively small. Different methods were presented for combining models of regional and interregional scale. It was found to be more important to include interregional information in regional-scale models for annual computations compared to episodic computations. A variety of linkage problems were noted between atmospheric and ecological models. The vertical distribution of pollutants and 'forest fittering' of pollutant deposition were found to be important in ecological impact calculations but lacking in the output of most interregional atmospheric models.