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Abstract:
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A monthly resolved coral δ18O record from Sabine Bank , Vanuatu (SBV ; 166 .04° E , 15 .94°S ) , extending from 2006 to 1929 CE , is used to assess the influence of sea surface salinity (SSS ) on the oxygen isotopic composition of coral aragonite at this location . Monthly SSS anomalies at SBV between 2006 and 1970 are strongly correlated with monthly anomalies in sea surface temperature (SST ) variations in the central Pacific cold tongue , as recorded by SST anomalies in the Niño 3 .4 grid box (i .e . , canonical record of ENSO variability , r = 0 .68 , p < 0 .01 ; lag of 6 months ) . This relationship demonstrates that SSS in the waters offshore of Vanuatu respond to ENSO -driven changes in the coupled ocean -atmosphere system in the tropical Pacific . SBV coral δ18O is also strongly correlated with monthly instrumental SSS anomalies at Vanuatu (r = 0 .71 , p < 0 .01 ) , therefore SBV coral δ18O variations are driven by the ENSO -related changes in surface ocean conditions . A calibration -verification exercise using SBV coral δ18O values and instrumental SSS was performed over the period 2006 -1970 CE . A statistically robust transfer function was determined and used to predict SSS at SBV back to 1929 CE . The coral δ18O and SSS relationship at Vanuatu is further evaluated via comparison with a coral δ18O record from Malo Channel , Vanuatu , a site that is 130 km to the east of SBV . The strong correlation between the two coral δ18O records (r = 0 .70 ; p < 0 .01 ) suggests that ENSO drives regional changes in SSS in this region and that such changes can be reconstructed using variations in skeletal δ18O of corals . |