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| Titel |
An observed 20-year time series of Agulhas leakage |
| VerfasserIn |
D. Bars, J. V. Durgadoo, H. A. Dijkstra, A. Biastoch, W. P. M. Ruijter |
| 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. 4 ; Nr. 10, no. 4 (2014-07-03), S.601-609 |
| Datensatznummer |
250117034
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| Publikation (Nr.) |
 copernicus.org/os-10-601-2014.pdf |
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| Zusammenfassung |
| We provide a time series of Agulhas leakage anomalies over the last 20-years from satellite altimetry. Until now, measuring the interannual
variability of Indo-Atlantic exchange has been the major barrier in the
investigation of the dynamics and large scale impact of Agulhas leakage. We
compute the difference of transport between the Agulhas Current and Agulhas
Return Current, which allows us to deduce Agulhas leakage. The main difficulty
is to separate the Agulhas Return Current from the southern limb of the
subtropical "supergyre" south of Africa. For this purpose, an algorithm
that uses absolute dynamic topography data is developed. The algorithm is
applied to a state-of-the-art ocean model. The comparison with a Lagrangian
method to measure the leakage allows us to validate the new method. An
important result is that it is possible to measure Agulhas leakage in this
model using the velocity field along a section that crosses both the Agulhas
Current and the Agulhas Return Current. In the model a good correlation is
found between measuring leakage using the full depth velocities and using
only the surface geostrophic velocities. This allows us to extend the method
to along-track absolute dynamic topography from satellites. It is shown that
the accuracy of the mean dynamic topography does not allow us to determine
the mean leakage but that leakage anomalies can be accurately computed. |
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