Trends in air mass frequencies across Europe

Climate change is one of the greatest challenges facing humanity today. Its effects are already being felt, and urgent action is needed to mitigate and adapt to these changes. Most climate change research is focused on the trends in individual meteorological variables (absolute moisture, temperature, relative humidity, sea-level pressure, etc.), but the study of multivariate manifestations of climate change remains largely unexplored. The aim of this research is to examine the changes in the frequency of air masses (AMs) over Europe since 1979, utilizing a recently developed gridded weather typing classification (GWTC2) system. On average, across the study domain, warm AMs have increased by 27 days/year over the 41-year period of study, humid warm AMs by 18 days/year, and dry warm AMs by an additional 14 days per year. In contrast, the continent has experienced a decreased frequency of cool AMs (− 33 days/year) and dry cool AMs (− 14 days/year). The most notable changes are in the polar regions (parts of North Sea, Norwegian Sea, Greenland Sea, and Barents Sea), where the humid warm AM and warm AM have increased by 38 days/year and 36 days/year, respectively, while dry and dry cool AMs have decreased by − 51 days/year and − 29 days/year, respectively, on average. Also, significant changes in the frequency of warm (+ 31 days/year) and cool AMs (− 31 days/year) are occurring in Central and Northern Europe. The warm and cold fronts (WFP and CFP AMs) show slight reductions in most of the study regions, but to a lesser extent than the other AMs.