Patterns of precipitation and pollutant deposition in the western Sudete mountains, Poland

The distribution of precipitation and wet deposition of pollutants by rain and snow in the western Sudete mountains in Poland has been investigated bo th for selected event case studies and for a longer term period of monitori ng. The results were compared with a numerical model of two-dimensional air flow and scavenging of cap cloud by precipitation. The results of both mode lling and analysis of case studies during north-westerly flow indicate that the first orographic barrier (Stog Izerski) receives the highest depositio n and acts to "shield" downstream hills (Szrenica). The "seeder-feeder effe ct" typically caused an increase in precipitation at Stog Izerski of about 50% relative to the upstream lowlands. Ion concentrations in cloud and rime water were consistently higher than those in rain and snow water. Spatial variations in deposition by snow were found by the model not to be as signi ficant as those for rain due to the slow fall speeds of snow crystals and t heir greater horizontal transport. The monitoring studies showed a maximum in sulphate and nitrate deposition at Stog Izerski. (C) 1999 Elsevier Scien ce Ltd. All rights reserved.