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ESF-MedCLIVAR Workshop Trieste 13-15 October 2008,

ESF-MedCLIVAR Workshop Trieste 13-15 October 2008, Influence of Mediterranean cyclones on Alpine precipitation Herbert Formayer Imran Nadeem and Patrick Haas Universität für Bodenkultur, Vienna Institute of Meteorology (BOKU-Met). Introduction.

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ESF-MedCLIVAR Workshop Trieste 13-15 October 2008,

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  1. ESF-MedCLIVAR Workshop Trieste 13-15 October 2008, Influence of Mediterranean cyclones on Alpine precipitation Herbert Formayer Imran Nadeem and Patrick Haas Universität für Bodenkultur, ViennaInstitute of Meteorology (BOKU-Met) ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  2. Introduction • The Mediterranean sea is one of the most important moisture sources for alpine precipitation. • Of course it is the main source for the south side of the Alps. • But even on the north side of the Alps air masses from the Mediterranean sea are responsible for large scale heavy precipitation events and flooding, as in May 1999, August 2002 and August 2005 • Cut-off lows centred near the Alps are mainly responsible for this heavy precipitation events . ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  3. Live cycle of cut-off lows Upper level trough Tear-off Cut-off Final stage ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  4. Sub-regions of cut-off lows affecting the alps ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  5. Precipitation anomaly associated with cut-off lows close to the alps Winter (DJF) NE NW SW SE ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  6. Precipitation anomaly associated with cut-off lows close to the alps NW NE SE SW Summer (JJA) ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  7. Case study: May 1999 19.05.1999 20.05.1999 21.05.1999 22.05.1999 ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  8. Case study: May 1999 20. – 22.05.1999 precipitation sum and track of the cut-off low ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  9. Case study: May 1999 Observed Precipitation ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  10. Case study: May 1999 MM5 ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  11. Case study: May 1999 ALADIN ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  12. Case study: July 1981 19810718 RegCM3 (50 km) Reanalyses ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  13. Case study: July 1981 19810719 RegCM3 (50 km) Reanalyses ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  14. Case study: July 1981 19810720 RegCM3 (50 km) Reanalyses ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  15. Case study: July 1981 19810721 RegCM3 (50 km) Reanalyses ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  16. Case study: July 1981 19810718 RegCM3 (50 km) Precipitation sums (daily) Observations ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  17. Case study: July 1981 19810719 RegCM3 (50 km) Precipitation sums (daily) Observations ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  18. Case study: June 1988 19880605 RegCM3 (50 km) Reanalyses ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  19. Case study: June 1988 19880606 RegCM3 (50 km) Reanalyses ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  20. Case study: June 1988 19880607 RegCM3 (50 km) Reanalyses ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  21. Case study: June 1988 19880605 RegCM3 (50 km) Precipitation sums (daily) Observations ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  22. Case study: June 1988 19880606 RegCM3 (50 km) Precipitation sums (daily) Observations ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  23. Conclusions • Mediterranean cyclones are important for the Alpine precipitation. • Many large scale alpine flooding events even on the north side of the Alps are associated with cut-off lows, transporting Mediterranean air-masses on the north side of the Alps. • Cut-off lows are not easy to handle by regional climate models (even so in NWP). ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  24. Big questions concerning climate change and cut-off lows: • Are GCMs able to reproduce Alpine relevant cut-off processes in a proper way concerning frequency, intensity, location and seasonality? • Can RCMs improve the behaviour of Alpine relevant cut-off lows? • If not, how can the GCMs be improved to do it in a better way and • How can hydrological modeller use the information about this important process for the interpretation of their results? ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

  25. We try to find some answers in the just started EC-Project: ACQWA http://www.unige.ch/climate/Projects/ACQWA.html Thank you for your attention ESF-MedCLIVAR Workshop Trieste 13-15 October 2008

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