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| Titel |
North Atlantic 20th century multidecadal variability in coupled climate models: sea surface temperature and ocean overturning circulation |
| VerfasserIn |
I. Medhaug, T. Furevik |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 7, no. 3 ; Nr. 7, no. 3 (2011-06-06), S.389-404 |
| Datensatznummer |
250004649
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| Publikation (Nr.) |
 copernicus.org/os-7-389-2011.pdf |
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| Zusammenfassung |
| Output from a total of 24 state-of-the-art Atmosphere-Ocean General
Circulation Models is analyzed. The models were integrated with observed
forcing for the period 1850–2000 as part of the Intergovernmental Panel on
Climate Change (IPCC) Fourth Assessment Report. All models show enhanced
variability at multi-decadal time scales in the North Atlantic sector similar
to the observations, but with a large intermodel spread in amplitudes and
frequencies for both the Atlantic Multidecadal Oscillation (AMO) and
the Atlantic Meridional Overturning Circulation (AMOC). The models, in
general, are able to reproduce the observed geographical patterns of warm and
cold episodes, but not the phasing such as the early warming (1930s–1950s) and
the following colder period (1960s–1980s). This indicates that the observed
20th century extreme in temperatures are due to primarily a fortuitous
phasing of intrinsic climate variability and not dominated by external
forcing. Most models show a realistic structure in the overturning
circulation, where more than half of the available models have a mean
overturning transport within the observed estimated range of 13–24 Sverdrup.
Associated with a stronger than normal AMOC, the surface temperature is
increased and the sea ice extent slightly reduced in the North Atlantic.
Individual models show potential for decadal prediction based on the
relationship between the AMO and AMOC, but the models strongly disagree both
in phasing and strength of the covariability. This makes it difficult to
identify common mechanisms and to assess the applicability for predictions. |
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