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Oceanic forcing of interannual and multidecadal climate variability in the southwestern Indian Ocean: Evidence from a 160 year coral isotopic record (La Réunion, 55°E, 21°S)
Leibniz Institut für Meereswissenschaften, IFM-GEOMAR, Kiel, Germany
Leibniz Institut für Meereswissenschaften, IFM-GEOMAR, Kiel, Germany
Leibniz Institut für Meereswissenschaften, IFM-GEOMAR, Kiel, Germany
Geological Survey of Denmark and Greenland, Copenhagen, Denmark
We have developed a new 163-year bimonthly coral δ18O record from La Réunion (55°E, 21°S). Interannual variations in coral δ18O are coherent with the Southern Oscillation Index but not with regional sea surface temperature (SST). Correlations with the global SST field suggest more negative seawater δ18O (δ18Osw) during La Niña years. We propose that the signal results from changes in the strength of the South Equatorial Current and the Indonesian throughflow, which carry low salinity water. Multidecadal variations in coral δ18O are coherent with regional SST, but the sign is of opposite sense as expected from the coral δ18O-temperature relationship. This requires multidecadal changes in salinity large enough to overprint the SST contribution in the coral δ18O record. Our results suggest that multidecadal salinity variations result from modulations in the transport of the South Equatorial Current, which varies in response to the surface wind field and/or the Indonesian throughflow.
Received 10 September 2003; accepted 6 August 2004; published 13 October 2004.
Citation: (2004), Oceanic forcing of interannual and multidecadal climate variability in the southwestern Indian Ocean: Evidence from a 160 year coral isotopic record (La Réunion, 55°E, 21°S), Paleoceanography, 19, PA4006, doi:10.1029/2003PA000964.
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