Warnsignal Klima: Änderung von Großwetterlagen und Bezug zu Wetterextremen

<em><strong>Climate warning signal: Changes in large-scale weather patterns and relation to weather extremes</strong></em> - A frequently used classification of large-scale circulation patterns (Grosswetterlagen, GWL) is that of Hess and Brezowsky. In order to analyze changes in their frequencies, objective methods are needed to classify the GWLs numerically and generate homogeneous time series. The new method, GWL-REA, uses global reanalysis data as input for determining GWL events and creating long-term catalogues. The analysis of the period 1961-2020 shows generally rather weak linear trends. The number of days with the GWL »Zonal Ridge across Central Europe« shows a statistically significant increase over the considered period. In the summer months this anticyclonic GWL can lead to short-duration heavy precipitation events. Other weather extremes are also often associated with certain GWLs, which is why the statistical analysis and forecasting of GWLs can be an important indicator for critical meteorological situations.