Characterizing joint effects of spatial extent, temperature magnitude and duration of heat waves and cold spells over Central Europe

Heat waves (HWs) and cold spells (CSs) have pronounced impacts on the natural environment and society. The main aim of this study was to identify major Central European HWs and CSs since 1950 and assess their severity not only from the viewpoint of temperature and duration but also as to the affected area. The HWs and CSs were delimited from the E-OBS gridded data set. An extremity index was proposed that captures joint effects of spatial extent, temperature and duration of HWs and CSs. During the 1950-2012 period, we identified 18 major HWs and 24 major CSs over Central Europe. The most severe HW occurred in summer 1994, followed by the 2006 HW; both these events were far more extreme over Central Europe than HWs in the well-known 2003 and 2010 summers. The most severe CSs occurred in the winters of 1955/1956 and 1962/1963. The recent winter of 2011/2012 was found to be the sixth coldest since 1950/1951 according to the seasonal sum of the extremity index. The HWs and CSs were classified through a hierarchical cluster analysis of their characteristics (temperature amplitude, spatial extent of the core and duration) into four basic types. The established list of major Central European HWs and CSs might be utilized in further analyses. The extremity index may be applied over different areas to perform comparative studies and used also for evaluation of regional climate model simulations.