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Titel |
North Atlantic climate variability in coupled models and data |
VerfasserIn |
S. K. Kravtsov, W. K. Dewar, M. Ghil, P. S. Berloff, J. C. McWilliams |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1023-5809
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Digitales Dokument |
URL |
Erschienen |
In: Nonlinear Processes in Geophysics ; 15, no. 1 ; Nr. 15, no. 1 (2008-01-18), S.13-24 |
Datensatznummer |
250012550
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Publikation (Nr.) |
copernicus.org/npg-15-13-2008.pdf |
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Zusammenfassung |
We show that the observed zonally averaged jet in the Northern Hemisphere
atmosphere exhibits two spatial patterns with broadband variability in the
decadal and inter-decadal range; these patterns are consistent with an
important role of local, mid-latitude ocean–atmosphere coupling. A key
aspect of this behaviour is the fundamentally nonlinear bi-stability of the
atmospheric jet's latitudinal position, which enables relatively small
sea-surface temperature anomalies associated with ocean processes to affect
the large-scale atmospheric winds. The wind anomalies induce, in turn,
complex three-dimensional anomalies in the ocean's main thermocline; in
particular, they may be responsible for recently reported cooling of the
upper ocean. Both observed modes of variability, decadal and inter-decadal,
have been found in our intermediate climate models. One mode resembles North
Atlantic tri-polar sea-surface temperature (SST) patterns described
elsewhere. The other mode, with mono-polar SST pattern, is novel; its key
aspects include interaction of oceanic turbulence with the large-scale
oceanic flow. To the extent these anomalies exist, the interpretation of
observed climate variability in terms of natural and human-induced changes
will be affected. Coupled mid-latitude ocean-atmosphere modes do, however,
suggest some degree of predictability is possible. |
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