Changes in Precipitation Conditions in the Warm Half-Year in the Polish–Saxon Border Region in Relation to the Atmospheric Circulation

Abstract

Precipitations are one of the most important factors affecting water resources in the transboundary Polish–Saxon region. The main goal of the research was to examine the multiannual changes in precipitations in the April–September period in 1971–2018, depending on circulation conditions, based on Ojrzyńska’s classification. The analysis was carried out based on meteorological data from Polish and German meteorological stations. The results showed that most of precipitation totals and intensive precipitations were observed under SW-A and SW-C circulation, whereas the anticyclonic types of NE-A, NW-A and SW-A were mainly responsible for dry days occurrence. In terms of multiannual changes, most of the stations were characterized by insignificant trends for the considered indices. Some positive trends were observed for intensive precipitations in the lower hypsometric zones. In the mountains, a decreasing tendency dominated for both precipitation totals and intensive precipitations, especially for the northern types of circulation. Furthermore, a significant increase was reported throughout the region for most of the indices for the SW-A type, including precipitation totals, strong precipitations and dry days. Considering the observed trends, floods related to heavy rains can intensify in the lowlands, while a potential increase in the anticyclonic circulation can significantly limit water resources in the region.