Decoupling of the Agulhas leakage from the Agulhas Current.

Loveday, Benjamin R., Durgadoo, Jonathan V. , Reason, Chris J.C., Biastoch, Arne and Penven, Pierrick (2014) Decoupling of the Agulhas leakage from the Agulhas Current. Open Access Journal of Physical Oceanography, 44 (7). pp. 1776-1797. DOI 10.1175/JPO-D-13-093.1.

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The relationship between the Agulhas Current and the Agulhas leakage is not well understood. Here, this is investigated using two basin-scale and two global ocean models, of incrementally increasing resolution. The response of the Agulhas Current is evaluated under a series of sensitivity experiments, in which idealised anomalies, designed to geometrically modulate zonal trade wind stress, are applied across the Indian Ocean basin. The imposed wind stress changes exceed ±2 standard deviations from the annual mean trade winds and, in the case of intensification, are partially representative of recently observed trends.

The Agulhas leakage is quantified using complimentary techniques based on Lagrangian virtual floats and Eulerian passive tracer flux. As resolution increases, model behavior converges and the sensitivity of the leakage to Agulhas Current transport anomalies is reduced. In the two eddy-resolving configurations tested, the leakage is insensitive to changes in Agulhas Current transport at 32°S, though substantial eddy kinetic energy anomalies are evident. Consistent with observations, the position of the retroflection remains stable.
The decoupling of Agulhas Current variability from the Agulhas leakage suggests that, while correlations between the two may exist, they may not have a clear dynamical basis. It is suggested that present and future Agulhas leakage proxies be considered in the context of potentially transient forcing regimes.

Document Type: Article
Funder compliance: info:eu-repo/grantAgreement/EC/FP7/238512
Additional Information: WOS:000339183800006
Keywords: Agulhas leakage; Agulhas Current
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-TM Theory and Modeling
Refereed: Yes
Open Access Journal?: No
Publisher: AMS (American Meteorological Society)
Projects: GATEWAYS, SPACES, Future Ocean
Date Deposited: 12 May 2014 11:49
Last Modified: 12 Apr 2018 12:47

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