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SUMMARY:Is the mid-latitude winter storm frequency predictable? - Dr Grego
 r Leckebusch\, University of Birmingham
DTSTART:20160523T131500Z
DTEND:20160523T141500Z
UID:TALK65779@talks.cam.ac.uk
CONTACT:Dr Marcus Koehler
DESCRIPTION:Severe damages and large insured losses over Europe related to
  natural phenomena are mostly caused by extra-tropical cyclones and their 
 related windstorm fields. Thus\, an adequate representation of these event
 s in seasonal prediction systems and reliable forecasts up to a season in 
 advance would be of high value for society and economy. In this study\, st
 ate-of-the-art seasonal forecast prediction systems are analysed (ECMWF\, 
 Met Office) regarding the general climatological representation and the se
 asonal prediction of extra-tropical cyclones and windstorms during the cor
 e winter season (DJF) with a lead time of up to four months.\n\nCyclones a
 re identified using six hourly mean sea level pressure data\, whereas wind
  storms are tracked based on 6 hourly 10m wind speed (ECMWF) and 12 hourly
  wind speeds in 925hPa (ECMWF & Met Office). Thus\, these analyses gain a 
 deeper insight into the representation of extra-tropical cyclones and thei
 r related wind storm fields in state-of-the-art seasonal forecasting suite
 s. Spatial distributions of both wind storm and cyclone events show the we
 ll-known centres of activity observed in ERA40 & ERA-Interim reanalyses da
 ta. However\, large biases are found for some areas.\n\nThe skill of the d
 ifferent forecast systems is assessed using deterministic as well as proba
 bilistic measures (e.g.\, Ranked Probability Skill Score (RPSS)\, Brier Sk
 ill Score (BSS)\, and Anomalous Correlation Coefficient (ACC)). Statistics
  are carried out for a hemispheric perspective as focussed on several sub-
 regions (e.g. Northern Europe).\n\nResults reveal small\, but positive ski
 ll for the North-Atlantic / European region as well as for the North-Pacif
 ic region depending on the model suite and variable investigated. Principl
 e reasons for positive skill (predictability) for extreme wind storm frequ
 ency are discussed. \n\nAcknowledgments: with special thanks to: Daniel J.
  Befort\, S.B. Wild (Uni Birmingham)\, A. Weisheimer (ECMWF)\, J. Roberts\
 , H. Thornton\, J. Knight\, L. Hermanson\, Philip Bett (UK MetOffice)
LOCATION:Unilever Lecture Theatre\, Department of Chemistry
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