Indian Ocean sources of Agulhas leakage

Durgadoo, Jonathan V., Rühs, Siren, Biastoch, Arne and Böning, Claus W. (2017) Indian Ocean sources of Agulhas leakage Journal of Geophysical Research: Oceans, 122 (4). pp. 3481-3499. DOI 10.1002/2016JC012676.

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Abstract

We examine the mean pathways, transit timescales, and transformation of waters flowing from the Pacific and the marginal seas through the Indian Ocean (IO) on their way toward the South Atlantic within a high-resolution ocean/sea-ice model. The model fields are analyzed from a Lagrangian perspective where water volumes are tracked as they enter the IO. The IO contributes 12.6 Sv to Agulhas leakage, which within the model is 14.1 ± 2.2 Sv, the rest originates from the South Atlantic. The Indonesian Through-flow constitutes about half of the IO contribution, is surface bound, cools and salinificates as it leaves the basin within 10–30 years. Waters entering the IO south of Australia are at intermediate depths and maintain their temperature-salinity properties as they exit the basin within 15–35 years. Of these waters, the contribution from Tasman leakage is 1.4 Sv. The rest stem from recirculation from the frontal regions of the Southern Ocean. The marginal seas export 1.0 Sv into the Atlantic within 15–40 years, and the waters cool and freshen on-route. However, the model's simulation of waters from the Gulfs of Aden and Oman are too light and hence overly influenced by upper ocean circulations. In the Cape Basin, Agulhas leakage is well mixed. On-route, temperature-salinity transformations occur predominantly in the Arabian Sea and within the greater Agulhas Current region. Overall, the IO exports at least 7.9 Sv from the Pacific to the Atlantic, thereby quantifying the strength of the upper cell of the global conveyor belt.

Document Type: Article
Keywords: Indian Ocean; pathways; Agulhas leakage; global conveyor belt
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-TM Theory and Modeling
OceanRep > The Future Ocean - Cluster of Excellence > FO-R11
Kiel University
Refereed: Yes
DOI etc.: 10.1002/2016JC012676
ISSN: 2169-9275
Projects: DRAKKAR, Future Ocean
Date Deposited: 29 May 2017 07:22
Last Modified: 19 Dec 2017 12:46
URI: http://eprints.uni-kiel.de/id/eprint/38080

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