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An Observed 20 Yr Time-series of Agulhas Leakage : Volume 11, Issue 1 (15/01/2014)

By Le Bars, D.

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Book Id: WPLBN0004020790
Format Type: PDF Article :
File Size: Pages 26
Reproduction Date: 2015

Title: An Observed 20 Yr Time-series of Agulhas Leakage : Volume 11, Issue 1 (15/01/2014)  
Author: Le Bars, D.
Volume: Vol. 11, Issue 1
Language: English
Subject: Science, Ocean, Science
Collections: Periodicals: Journal and Magazine Collection, Copernicus GmbH
Publication Date:
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications


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Biastoch, A., Dijkstra, H. A., M. De Ruijte, W. P., Durgadoo, J. V., & Bars, D. L. (2014). An Observed 20 Yr Time-series of Agulhas Leakage : Volume 11, Issue 1 (15/01/2014). Retrieved from

Description: IMAU, Utrecht University, P.O. Box 80.005, 3508 TA Utrecht, the Netherlands. We provide a time series of Agulhas leakage anomalies over the last twenty 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 Agulhas Current and Agulhas Return Current which allows 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 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 to determine the mean leakage but that leakage anomalies can be accurately computed.

An observed 20 yr time-series of Agulhas leakage

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