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Titel |
Paleo Agulhas rings enter the subtropical gyre during the penultimate deglaciation |
VerfasserIn |
P. Scussolini, E. van Sebille, J. V. Durgadoo |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1814-9324
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Digitales Dokument |
URL |
Erschienen |
In: Climate of the Past ; 9, no. 6 ; Nr. 9, no. 6 (2013-11-25), S.2631-2639 |
Datensatznummer |
250085264
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Publikation (Nr.) |
copernicus.org/cp-9-2631-2013.pdf |
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Zusammenfassung |
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 δ18O. 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. |
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