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| Titel |
On the relationship between ENSO, Stratospheric Sudden Warmings and Blocking |
| VerfasserIn |
David Barriopedro, Natalia Calvo |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250093669
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| Publikation (Nr.) |
 EGU/EGU2014-8613.pdf |
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| Zusammenfassung |
| Using the 1958-2010 period of the ERA-40 and ERA-I reanalyses, we examine the influence
of El Niño-Southern Oscillation (ENSO) on different aspects of Stratospheric Sudden
Warmings (SSWs) and atmospheric blocking, including the blocking precursors of
SSWs.
Our results reveal that SSWs are preceded by blocking patterns over different regions
depending on the ENSO phase. Euro-Atlantic and western Atlantic blocks tend to precede
SSWs during El Niño (EN), whereas Eastern Pacific and Siberian blocks are the preferred
precursors of SSWs during La Niña (LN) winters. This ENSO signal on the blocking
precursors of SSWs is larger than that obtained in previous studies by stratifying the SSWs
into splitting and displacement SSWs.
It is also found that the regional blocking precursors of SSWs during each ENSO phase
have different impacts on the upward propagation of planetary-scale wave number 1
and 2, and hence determine ENSO differences in the wave number signatures of
SSWs. SSWs occurring during EN are preceded by amplification of wave number 1,
whereas LN SSWs are predominantly associated to wave number 2 amplification. This
leads to an unbalanced frequency of wave-1 and wave-2 SSWs between opposite
ENSO phases. However, there is not a strong preference for splitting or displacement
SSWs during any ENSO phase due to a lack of correspondence between wave-2 and
splitting SSWs. In particular, during EN, splitting SSWs do not show a wave-2 pattern. |
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