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Titel |
Conditional nonlinear optimal perturbations of the double-gyre ocean circulation |
VerfasserIn |
A. D. Terwisscha van Scheltinga, 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 ; 15, no. 5 ; Nr. 15, no. 5 (2008-10-10), S.727-734 |
Datensatznummer |
250012759
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Publikation (Nr.) |
copernicus.org/npg-15-727-2008.pdf |
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Zusammenfassung |
In this paper, we study the development of finite amplitude perturbations on linearly
stable steady barotropic double-gyre flows in a rectangular basin using the concept
of Conditional Nonlinear Optimal Perturbation (CNOP). The CNOPs depend on a time
scale of evolution te and an initial perturbation threshold δ. Under symmetric
wind forcing, a perfect pitchfork perturbation occurs in the model. The CNOPs
are determined for all linearly stable states and the time evolution of the CNOPs
is studied. It is found that the patterns of the CNOPs are similar to those of the
non-normal modes for small te and approach those of the normal modes for
larger te. With slightly asymmetric winds, an imperfect pitchfork occurs in the
model. Indications are found that the time evolution of the CNOPs is related to
the value of the dissipation function of the underlying steady state. |
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