Large-scale heavy precipitation over central Europe and the role of atmospheric cyclone track types.

Precipitation patterns over Europe are largely controlled by atmospheric cyclones embedded in the general circulation of the mid-latitudes. This study evaluates the climatologic features of precipitation for selected regions in central Europe with respect to cyclone track types for 1959-2015, focusing on large-scale heavy precipitation. The analysis suggests that each of the cyclone track types is connected to a specific pattern of the upper level atmospheric flow, usually characterized by a major trough located over Europe. A dominant upper level cut-off low (COL) is found over Europe for strong continental (CON) and van Bebber's type (Vb) cyclones which move from the east and southeast into central Europe. Strong Vb cyclones revealed the longest residence times, mainly due to circular propagation paths. The central European cyclone precipitation climate can largely be explained by seasonal track-type frequency and cyclone intensity; however, additional factors are needed to explain a secondary precipitation maximum in early autumn. The occurrence of large precipitation totals for track events is strongly related to the track type and the region, with the highest value of 45% of all Vb cyclones connected to heavy precipitation in summer over the Czech Republic and eastern Austria. In western Germany, Atlantic winter cyclones are most relevant for heavy precipitation. The analysis of the top 50 precipitation events revealed an outstanding heavy precipitation period from 2006 to 2011 in the Czech Republic, but no gradual long-term change. The findings help better understand spatio-temporal variability of heavy precipitation in the context of floods and may be used for evaluating climate models.