Coldwaves in Poland - frequency, trends and relationships with atmospheric circulation

Abstract

The daily minimum and maximum temperatures at nine stations in Poland were used in an analysis of the occurrence of coldwaves, where these are defined as days with temperatures exceeding selected thresholds (tmin ≤ -20°C, tmin ≤ -15°C and tmax≤ -10°C) in the period 1951-2006. Cold nights occurred more often than very cold days and nights but the mean lengths of waves of cold nights were similar - lasting a little more than 2 days on average. The frequencies of extremely cold days revealed a slight, but statistically non-significant downward trend. The occurrence of coldwaves was associated with high-pressure systems over Central Europe and with blocking episodes, but it was always linked with a thick layer of cold air.