Intra-seasonal characteristics of cold winters in Europe

<p>Extreme cold spells exert serious impacts on society by affecting agriculture, the energy supply and the environment. In this respect, here we investigate the spatio-temporal characteristics of extremely cold winters in Europe over the last 70 years and their large-scale drivers. The characteristics of extreme cold events (e.g. magnitude, frequency, trends) are investigated in terms of month-to-month variability from December to March. Overall, we observed a significant decreasing trend both in the length and the frequency of cold spells at the European level. Long-lasting cold spells are most frequent in January in the south-eastern part of Europe and in March over the central part of Europe. The most severe cold spells occurred in 1955/1956, 1962/1963, and 2010/2011. Widespread cold extremes over the central and the northern part of Europe are favored by the negative phase of North Atlantic Oscillation, associated with advection of continental air masses from the east, clear skies and negative anomalies in downward longwave radiation. Over the Mediterranean region, cold spells are less common and are mainly influenced by the East Atlantic teleconnection pattern. Our results add to the understanding of the spatio-temporal variability of cold winters, at the European level, as well as their driving mechanisms.</p>