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| Titel |
The role of subpolar deep water formation and Nordic Seas overflows in simulated multidecadal variability of the Atlantic meridional overturning circulation |
| VerfasserIn |
K. Lohmann, J. H. Jungclaus, D. Matei, J. Mignot, M. Menary, H. R. Langehaug, J. Ba, Y. Gao, O. H. Otterå, W. Park, S. Lorenz |
| 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 ; 10, no. 2 ; Nr. 10, no. 2 (2014-04-14), S.227-241 |
| Datensatznummer |
250116967
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| Publikation (Nr.) |
 copernicus.org/os-10-227-2014.pdf |
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| Zusammenfassung |
| We investigate the respective role of variations in subpolar deep water
formation and Nordic Seas overflows for the decadal to multidecadal
variability of the Atlantic meridional overturning circulation (AMOC). This
is partly done by analysing long (order of 1000 years) control simulations
with five coupled climate models. For all models, the maximum influence of
variations in subpolar deep water formation is found at about
45° N, while the maximum influence of variations in Nordic Seas
overflows is rather found at 55 to 60° N. Regarding
the two overflow branches, the influence of variations in the Denmark Strait
overflow is, for all models, substantially larger than that of variations in
the overflow across the Iceland–Scotland Ridge. The latter might, however, be
underestimated, as the models in general do not realistically simulate the
flow path of the Iceland–Scotland overflow water south of the
Iceland–Scotland Ridge. The influence of variations in subpolar deep water
formation is, on multimodel average, larger than that of variations in the
Denmark Strait overflow. This is true both at 45° N, where the
maximum standard deviation of decadal to multidecadal AMOC variability is
located for all but one model, and at the more classical latitude of
30° N. At 30° N, variations in subpolar deep water
formation and Denmark Strait overflow explain, on multimodel average, about
half and one-third respectively of the decadal to multidecadal AMOC variance.
Apart from analysing multimodel control simulations, we have performed
sensitivity experiments with one of the models, in which we suppress the
variability of either subpolar deep water formation or Nordic Seas overflows.
The sensitivity experiments indicate that variations in subpolar deep water
formation and Nordic Seas overflows are not completely independent. We
further conclude from these experiments that the decadal to multidecadal AMOC
variability north of about 50° N is mainly related to variations in
Nordic Seas overflows. At 45° N and south of this latitude,
variations in both subpolar deep water formation and Nordic Seas overflows
contribute to the AMOC variability, with neither of the processes being very
dominant compared to the other. |
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