Climate Change and Circulation Types in the Alpine Region

Weather or circulation type classifications (CTCs) are widely used to analyze weather and climate conditions as a tool to separate the state of the atmosphere into groups with similar and recurrent characteristics. In this study the frequency and persistence of circulation types over the Alpine region is explored using 19 different regional climate models. The projected changes in these circulation types are investigated for the 21st century using a A1B greenhouse gas emission scenario. The multiͲmodel approach used relays on the regional climate models from the ENSEMBLES project and circulation type classifications provided by the COST Action 733. For the latter two circulation type classifications, GWT (GrossWetterTypes) and CAP (Cluster Analysis of Principal components), as in operational use at the Federal Office of Meteorology and Climatology MeteoSwiss are used.