A new classification scheme of European cyclone tracks with relevance to precipitation.

This paper proposes a new classification scheme of atmospheric cyclone tracks over Europe. The cyclones are classified into nine types, based on the geographic regions, the cyclones traverse before entering central Europe. The method is applied to ERA-40 data for 1961-2002, considering all significant cyclones above a relative vorticity threshold. About 120 and 80 cyclone tracks per year are identified at sea level pressure and 700 hPa geopotential height, respectively. About 25% are Atlantic type cyclones, 25% emerge directly over central Europe, and another 25% originate from the lee of the Alps. The other types are less frequent (Mediterranean 12%, Polar 7%, Continental 2%, and Vb 4%). The track types show distinct characteristics in terms of cyclone intensity and cyclone life stage when entering central Europe. Cyclones of type Vb are, on average, the most intense cyclones over central Europe and even more intense than Atlantic cyclones in summer, pointing to their potential for generating extreme precipitation. The identified cyclones account for 46%-76% of long-term precipitation in a focus region in central Europe. Precipitation differs significantly between cyclones, with Atlantic and Vb cyclones producing the highest and Continental and Polar cyclones producing the lowest long-term precipitation totals. The contributions of cyclone types to total precipitation show distinct spatial patterns within central Europe. The new cyclone type catalog will be useful for identifying the relevance of specific track types for precipitation extremes in central Europe and analyze their temporal behavior in the context of climate change. [ABSTRACT FROM AUTHOR]