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Titel |
A Lagrangian approach to the Loop Current eddy separation |
VerfasserIn |
F. Andrade-Canto, J. Sheinbaum, L. Zavala Sansón |
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 ; 20, no. 1 ; Nr. 20, no. 1 (2013-01-23), S.85-96 |
Datensatznummer |
250017731
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Publikation (Nr.) |
copernicus.org/npg-20-85-2013.pdf |
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Zusammenfassung |
Determining when and how a Loop Current eddy
(LCE) in the Gulf of Mexico will finally separate is a difficult
task, since several detachment re-attachment processes
can occur during one of these events. Separation is usually defined
based on snapshots of Eulerian fields such as sea surface height (SSH)
but here we suggest that a Lagrangian view of the LCE separation process is
more appropriate and objective. The basic idea is very simple:
separation should be defined whenever water particles
from the cyclonic side of the Loop Current move
swiftly from the Yucatan Peninsula to the Florida Straits instead
of penetrating into the NE Gulf of Mexico.
The properties of backward-time
finite time Lyapunov exponents (FTLE)
computed from a numerical
model of the Gulf of Mexico and Caribbean Sea are used to
estimate the "skeleton" of flow and the structures involved in
LCE detachment events.
An Eulerian metric is defined,
based on the slope of the strain direction of the instantaneous
hyperbolic point of the Loop Current anticyclone that provides
useful information to forecast final LCE detachments. We
highlight cases in which an LCE separation metric based on SSH
contours (Leben, 2005) suggests there is a
separated LCE that later reattaches, whereas the
slope method and FTLE structure indicate the eddy remains dynamically
connected to the Loop Current during the process. |
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