Implications of enhanced persistence of atmospheric circulation over Europe for the occurrence and severity of temperature extremes
Jan Kysely, Institute of Atmospheric Physics, Prague, Czech Republic
Relationships between persistent atmospheric circulation patterns over Europe and surface air temperature anomalies are studied over the 20th century using the Hess-Brezowsky catalogue of circulation types and temperature data from European stations with long-term measurements. Circulation types significantly conducive to heat and cold waves are detected. It is demonstrated that the persistence of the circulation patterns is linked to surface air temperature anomalies and the occurrence and severity of temperature extremes that are more pronounced under more persistent circulation. The consequences vary for warm and cold extremes and among sites, depending on features related to the atmospheric dynamics (e.g. air-mass advection and atmospheric fronts); the intensification due to the higher persistence of circulation patterns would be more important for warm than cold extremes. The recently observed increases in the frequency and severity of heat waves over Europe are likely related to the enhanced persistence of the atmospheric circulation, and impacts of the expected climate change on the occurrence and severity of temperature extremes may be exacerbated by more persistent circulation patterns over European mid-latitudes. The study is supported by the Czech Science Foundation under grant project 205/06/1535.
Joint Poster Session 4, Joint Poster: Climate & Extremes, Linking Weather and Climate (Joint with Second Symposium on Policy and Socio-economic Research, Symposium on Connections Between Mesoscale Processes and Climate Variability, 19th Conference on Climate Variability and Change, and Climate Change Manifested by Changes in Weather)
Wednesday, 17 January 2007, 2:30 PM-4:00 PM, Exhibit Hall C
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