Atmospheric circulation variability in Europe and northern Asia (1901 to 2010)

Abstract

Climate variability in Europe and northern Asia is markedly affected by changes in atmospheric circulation. Two manual catalogues of large-scale circulation patterns, the ‘Grosswetterlagen’ (GWLc) and ‘Vangengeim-Girs’ classifications (VGc), were analysed and compared to detect frequency changes of circulation forms. Results were compared with variations of ‘objective’ references: variations of the North Atlantic Oscillation (NAO) and a hybrid version of the GWLc (SynopVis Grosswetterlagen catalogue, SVGc). Changes were investigated for 1901–2010, focussing on the most recent climate normal (1981–2010). Trends are moderate in the winter half year (WHY), but rather consistent between the approaches. Circulation variability within VGc/NAO and GWLc/SVGc largely agrees. In the summer half year, large trends are visible in VGc and GWLc, but their objective support by the SVGc, showing comparably small changes, is low. Changes in the distribution of circulation patterns likely fostered a larger temperature increase in the investigated regions compared to global average temperatures during the past 30 years in the WHY. The results of this study help further in investigating temperature and precipitation changes in both Europe and northern Asia.