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| Titel |
Winter atmospheric modes of variability over North America: the added value of RCMs on the large-scale atmospheric signal |
| VerfasserIn |
Ramon Fuentes-Franco, Federico Graef, Edgar Pavia, Filippo Giorgi |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250107933
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| Publikation (Nr.) |
 EGU/EGU2015-7654.pdf |
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| Zusammenfassung |
| In this work we assess the skill of the Regional Climate Model RegCM4 in reproducing
atmospheric variability modes (AVM) during winter compared to a couple of GCMs used as
boundary conditions for a RegCM4 historical (1970-2005) simulation. The AVMs are
obtained from empirical orthogonal functions of 500 hPa geopotential height anomalies
(Z500). The RegCM4 simulations improve the spatial representation of the AVMs compared
to the GCMs’, as shown by a correlation analysis between simulations and observations
(reanalysis). For the 21st Century projections we found that the first AVM is an
inhomogeneous atmospheric expansion which induces changes in the atmospheric circulation
favoring the advection of oceanic humidity, and therefore precipitation in the Southwestern
US and Northwestern Mexico (SWUS-NWMX) region. The second AVM represents a dipole
of zonal expansion-compression which apparently modulates the interannual precipitation
variability in the SWUS-NWMX region. This second mode is a response to El Niño:
accountable for the occurrence of very wet and very dry winters in the region; therefore this is
the cause for the projected increase in interannual variability of winter precipitation. |
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