An observed 20-year time series of Agulhas leakage.

Le Bars, D., Durgadoo, J. V., Dijkstra, H. A., Biastoch, Arne and De Ruijter, W. P. M. (2014) An observed 20-year time series of Agulhas leakage. Open Access Ocean Science, 10 (4). pp. 601-609. DOI 10.5194/os-10-601-2014.

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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.

Document Type: Article
Funder compliance: info:eu-repo/grantAgreement/EC/FP7/238512
Additional Information: WOS:000340106300002
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-TM Theory and Modeling
Refereed: Yes
Open Access Journal?: Yes
Publisher: Copernicus Publications (EGU)
Projects: GATEWAYS, SPACES, Future Ocean
Date Deposited: 05 Sep 2014 08:55
Last Modified: 23 Sep 2019 23:57

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