Cold Waves in Poland: The Relations to Atmospheric Circulation and Arctic Warming

Abstract

Winter warming in Europe is most apparent in the northeastern parts. The minimum temperature is increasing there at the rate of 0.5°C–0.7°C per decade. The main objective of the paper was to investigate the changes in the characteristics of cold days (CDs) and cold waves (CWs) in Poland. Then, to study the relationships and changes in the large-scale circulation with regard to CWs in Poland. Due to the increasing minimum temperature, Poland is characterised by a decreasing number of CDs and CWs from November to March 1978–2023. In recent years, CDs in Poland have been significantly less severe and are less extended, whereas CWs occur less frequently and are shorter. Recent changes in temperature and sea-ice cover in the Arctic region entail changes in the large-scale circulation in mid and high latitudes. In the 20th century, CWs in Poland were mainly related to blocking created over Scandinavia and the North Atlantic (Iceland). In the 21st century, some shifts in the centers of action were found, and CWs in Poland are primarily associated with strong blocking created over the Greenland and Ural regions. These blocking situations are followed by a negative NAO/AO and positive Greenland Blocking Index or positive Scandinavian (SCAND) pattern, which are significantly correlated with CWs in winter (SCAND only in February). It needs to be emphasised that the Arctic region is one of the most important source areas of the air masses that reach Poland during the CDs, and this area faces the greatest warming around the globe.