boku-met herbert formayer esf-medclivar workshop trieste 13-15 october 2008 esf-medclivar workshop...
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BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
ESF-MedCLIVAR WorkshopTrieste 13-15 October 2008,
Influence of Mediterranean cyclones on Alpine precipitation
Herbert FormayerImran Nadeem and Patrick Haas
Universität für Bodenkultur, ViennaInstitute of Meteorology (BOKU-Met)
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
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 .
Introduction
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Upper level trough
Tear-off
Cut-off
Final stage
Live cycle of cut-off lows
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Sub-regions of cut-off lows affecting the alps
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Winter (DJF)
NW NE
SESW
Precipitation anomaly associated with cut-off lows
close to the alps
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Precipitation anomaly associated with cut-off lows
close to the alpsSummer (JJA)
NW NE
SW SE
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
19.05.1999 20.05.1999
21.05.1999 22.05.1999
Case study: May 1999
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
20. – 22.05.1999 precipitation sum and track of the cut-off low
Case study: May 1999
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Observed Precipitation
Case study: May 1999
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
MM5
Case study: May 1999
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
ALADIN
Case study: May 1999
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Reanalyses
Case study: July 1981
19810718RegCM3 (50 km)
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Case study: July 1981
19810719RegCM3 (50 km) Reanalyses
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Case study: July 1981
19810720
ReanalysesRegCM3 (50 km)
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Case study: July 1981
19810721
ReanalysesRegCM3 (50 km)
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Case study: July 1981
19810718RegCM3 (50 km)
Observations
Precipitation sums (daily)
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Case study: July 1981
19810719RegCM3 (50 km)
Observations
Precipitation sums (daily)
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Case study: June 1988
19880605
ReanalysesRegCM3 (50 km)
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Case study: June 1988
19880606
ReanalysesRegCM3 (50 km)
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Case study: June 1988
19880607
ReanalysesRegCM3 (50 km)
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Case study: June 1988
19880605RegCM3 (50 km)
Observations
Precipitation sums (daily)
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Case study: June 1988
19880606RegCM3 (50 km)
Observations
Precipitation sums (daily)
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
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).
Conclusions
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
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?
Big questions concerning climate change and cut-off
lows:
BOKU-MetHerbert Formayer
ESF-MedCLIVAR Workshop Trieste 13-15 October 2008
Thank you for your attention
We try to find some answers in the just started EC-Project:
ACQWA
http://www.unige.ch/climate/Projects/ACQWA.html