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| Titel |
Changing surface water conditions for the last 500 ka in the Southeast Atlantic:Tracking Agulhas leakage using UK37' and δD |
| VerfasserIn |
Benjamin Petrick, Erin McClymont, Marcel van der Meer, Fabienne Marret |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250108341
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| Publikation (Nr.) |
 EGU/EGU2015-8092.pdf |
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| Zusammenfassung |
| The Southeast Atlantic Ocean is an important component of global ocean circulation, as it
includes heat and salt transfer into the Atlantic through Agulhas Leakage. Here, we
reconstruct sea surface temperatures (SSTs) and sea surface salinity from Ocean Drilling
Program (ODP) Site 1087 in the Southeast Atlantic to investigate surface ocean circulation
patterns during the late Pleistocene (0-500 ka). The alkenone-derived U37K’index and
assemblages of dinoflagellate cysts are used to reconstruct SSTs. The hydrogen isotope
composition of the alkenones (δDalkenone) is used to reconstruct changes in sea-surface
salinity.
The greatest amplitude of SST warming precedes decreases in benthic δ18O and therefore
occurs early in the transition from glacials to interglacials. The timing of the early warming is
consistent with previously published foraminifera reconstructions from the same site (Caley
et al., 2012). However, δDalkenone decreases at the start of interglacials, suggesting that sea
surface salinity increased earlier than the deglacial warmings, and indicating that the
pattern of Agulhas leakage is more complex than suggested by SST proxies alone.
Furthermore, the δDalkenonevalues indicate a strong salinity increases occurred before both
MIS 11 and MIS 1, which are both periods where there is evidence of connection
between increased Agulhas Leakage and a stronger Atlantic meridional overturning
circulation (AMOC). Finally, the ODP site 1087 record shows an overall trend of
increasing SSTs and δDalkenone towards the present day, suggesting that Agulhas
leakage has strengthened since 500 ka, which may have impacted the intensity of the
AMOC.
Caley, T., Giraudeau, J., Malaize, B., Rossignol, L., Pierre, C., 2012. Agulhas leakage as a
key process in the modes of Quaternary climate changes. Proc. Natl. Acad. Sci. 109,
6835–6839. doi:10.1073/pnas.1115545109 |
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