Trends and Circulation Conditions of Precipitation Over the Sudeten Mountains (Central Europe) in the Years 1961–2020

ABSTRACT The study is focused on the trends of precipitation over the Sudetes in the era of the global changes of air temperature. The Sudeten Mts are in the central European region with ambiguous trends of precipitation changes. Due to the ecological disaster that took place at the end of the 20th century, the destabilised environment of the Sudetes is more sensitive to changes in temperature and humidity because of influence on biodiversity or height of bioclimatic zones, flood danger, or drinking water resources. The atmospheric circulation conditions combined with processes determined by terrain diversify the precipitation over the mountains. Because of a change in the frequency of certain atmospheric circulation conditions, the spatial and temporal distribution of precipitation over mountains is changing. The general aim was to identify the annual, seasonal and monthly significant changes in precipitation totals and number of days with precipitation, taking into consideration the role of atmospheric circulation types in observed trends and their spatial pattern. In the 60‐year period under analysis 1961–2020 and in the period extended to 2024, the high year‐to‐year variability of annual precipitation totals results in the lack of significant annual tendencies. However, significant trends of precipitation totals are visible at seasonal (negative in spring and positive in winter) and monthly level. Observed significant decreasing tendency of spring precipitation totals is disquieting especially in the context of access to water for plants in the beginning of the vegetation period. The deepening rainfall deficit in April in Western Sudetes threatens the stabilisation of forest ecosystems, the preservation of biodiversity and significantly limits water resources for economic use. Observed trends can be partially explained by changes in atmospheric circulation dynamics described by selected circulation types frequencies. Particularly visible is the impact of the increase in the occurrence of dry and anticyclonic groups of types in April and November, or cyclonic group of types with advection of polar maritime air in January.