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| Titel |
Intrinsic low-frequency variability of the Gulf Stream |
| VerfasserIn |
G. Quattrocchi, S. Pierini, H. A. Dijkstra |
| 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 ; 19, no. 2 ; Nr. 19, no. 2 (2012-03-05), S.155-164 |
| Datensatznummer |
250014184
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| Publikation (Nr.) |
 copernicus.org/npg-19-155-2012.pdf |
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| Zusammenfassung |
| In this paper a process study aimed at analyzing the
low-frequency variability of intrinsically oceanic origin of the Gulf Stream
(GS) and GS extension (GSE) is presented. An eddy-permitting reduced-gravity
nonlinear shallow water model is implemented in an idealized North Atlantic
Ocean, with schematic boundaries including the essential geometric features
of the coastline and a realistic zonal basin width at all latitudes. The
forcing is provided by a time-independent climatological surface wind stress
obtained from 41 years of monthly ECMWF fields. The model response yields
strong intrinsic low-frequency fluctuations on the interannual to decadal
time scales. The modelled time-averaged GS/GSE flows are found to exhibit
several features that can also be deduced from satellite altimeter data,
such as the Florida Current seaward deflection, the GS separation at Cape
Hatteras, and the overall structure of the GSE. The intrinsic low-frequency
variability yields two preferred states of the GSE differing in latitudinal
location that also have their counterpart in the altimeter data. A
preliminary analysis of the variability in terms of dynamical systems theory
is carried out by using the lateral eddy viscosity as the control parameter.
A complex transition sequence from a steady state to irregular low-frequency
variability emerges, in which Hopf and global bifurcations can be
identified. |
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