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| Titel |
Decadal variability and extremes of European winter storm frequency according to the Twentieth Century Reanalysis - a process-oriented analysis |
| VerfasserIn |
Tim Kruschke, Henning W. Rust, Bruno Schyska, Simon Wild, Gregor C. Leckebusch, Uwe Ulbrich |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250077528
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| Zusammenfassung |
| Winter storms, represented by extensive fields of extreme wind speeds, result from intense
extra-tropical cyclones. The most extreme of them cause enormous socio-economical losses
over Europe.
As part of the MiKlip initiative this study deals with the assessment of decadal variability of
synoptic-scale European winter storms in terms of their frequency and analyzes the processes
influencing this decadal variability. Analysis subject is the new Twentieth Century Reanalysis
(20CR) dataset, spanning the period 1871-2008.
The discrete winter storm events are identified by matching the results of two event tracking
schemes. One scheme identifies extra-tropical cyclones, based on MSLP and its
laplacian, the other is based only on surface wind speeds, thus identifies storm events
diagnosed as extensive areas of extreme (-¥ local climatological 98th percentile)
wind speeds. Hence, the definition of a European winter storm in the context of this
study is an extra-tropical cyclone producing synoptic scale fields of extreme surface
winds.
Based on this approach, the period of 1871-2008 (ONDJFM) is investigated with respect to
decadal variability of extreme winter storms and their frequency. Perennial periods of
anomalous high/low European winter storm frequency are analyzed regarding global
atmospheric and oceanic conditions – for the latter, taking additionally into account the
HadISST1.1 dataset, which was used to force 20CR – and their spatio-temporal evolution.
The aim of this analysis step is to reveal some of the physical mechanisms behind decadal
variability of winter storm frequency.
First results indicate a connection between the North Atlantic meridional SST gradient and
decadal extremes of European winter storm frequency, as well as some remote influence from
the Pacific basin and the tropics in general. |
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