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 both for selected event case studies and for a longer term period of monitoring. The results were compared with a numerical model of two-dimensional airflow and scavenging of cap cloud by precipitation. The results of both modelling and analysis of case studies during north-westerly flow indicate that the first orographic barrier (Stóg Izerski) receives the highest deposition and acts to “shield” downstream hills (Szrenica). The “seeder–feeder effect” typically caused an increase in precipitation at Stóg 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 significant as those for rain due to the slow fall speeds of snow crystals and their greater horizontal transport. The monitoring studies showed a maximum in sulphate and nitrate deposition at Stóg Izerski.