Paleo Agulhas rings enter the subtropical gyre during the penultimate deglaciation.

Scussolini, P., van Sebille, E. and Durgadoo, Jonathan V. (2013) Paleo Agulhas rings enter the subtropical gyre during the penultimate deglaciation. Open Access Climate of the Past, 9 (6). pp. 2631-2639. DOI 10.5194/cp-9-2631-2013.

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Abstract

A maximum in the strength of Agulhas leakage has been registered at the interface between the Indian and South Atlantic oceans during glacial Termination II (T-II). This presumably transported the salt and heat necessary for maintaining the Atlantic circulation at rates similar to the present day. However, it was never shown whether these waters were effectively incorporated into the South Atlantic gyre, or whether they retroflected into the Indian and/or Southern oceans. To resolve this question, we investigate the presence of paleo Agulhas rings from a sediment core on the central Walvis Ridge, almost 1800 km farther into the Atlantic Basin than previously studied. Analysis of a 60 yr data set from the global-nested INALT01 model allows us to relate density perturbations at the depth of the thermocline to the passage of individual rings over the core site. Using this relation from the numerical model as the basis for a proxy, we generate a time series of variability of individual Globorotalia truncatulinoides delta O-18. We reveal high levels of pycnocline depth variability at the site, suggesting enhanced numbers of Agulhas rings moving into the South Atlantic Gyre around T-II. Our record closely follows the published quantifications of Agulhas leakage from the east of the Cape Basin, and thus shows that Indian Ocean waters entered the South Atlantic circulation. This provides crucial support for the view of a prominent role of the Agulhas leakage in the shift from a glacial to an interglacial mode of the Atlantic circulation.

Document Type: Article
Funder compliance: info:eu-repo/grantAgreement/EC/FP7/238512
Keywords: Atlantic overturning circulation
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, Future Ocean
Expeditions/Models/Experiments:
Date Deposited: 06 Jan 2014 10:03
Last Modified: 23 Sep 2019 16:38
URI: https://oceanrep.geomar.de/id/eprint/22817

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