Recent increase in persistence of atmospheric circulation over Europe: Comparison with long-term variations since 1881

Long-term changes in the persistence of atmospheric circulation (measured by the mean residence time of circulation types) over Europe since 1881 are studied using the Hess-Brezowsky classification of Grosswelterlagen. A comprehensive statistical analysis is performed utilizing tests for change points, trends and outliers. The most remarkable feature of the long-term variations in the persistence of circulation patterns is a general sharp increase from the 1970s to the late 1980s. The shift towards higher persistence is statistically significant in most groups of the types and most seasons and is confirmed by all the statistical tools. The 1986-2000 period is an outlier, and the most pronounced change point in the time series appears in the mid-1980s. The observed increase in the mean lifetime of the circulation types over European mid-latitudes seems to be consistent with the idea of global warming, which is likely to shift the areas with the highest baroclinic activity (storm tracks) northwards. The enhanced persistence of the atmospheric circulation may have also supported the more frequent occurrence of temperature and other climatic extremes in Europe recently. Copyright (C) 2005 Royal Meteorological Society.