Sea surface temperature and salinity reconstruction based on stable isotopes and Mg/Ca of planktonic foraminifera in the western Pacific Warm Pool during the last 155 ka

Abstract

Changes in sea surface temperature (SST), seawater oxygen isotope (δ18Osw), and local salinity proxy (δ18Osw-ss) in the past 155 ka were studied using a sediment core (MD06-3052) from the northern edge of the western Pacific Warm Pool (WPWP), within the flow path of the bifurcation of the North Equatorial Current. Our records reveal a lead-lag relationship between paired Mg/Ca-SST and δ18O during Termination II and the last interglacial period. Similarity in SST between our site and the Antarctic temperature proxy and in CO2 profile showed a close connection between the WPWP and the Antarctic. Values of δ18O sw exhibited very similar variations to those of mean ocean δ18Osw, owing to the past sea-level changes on glacial-interglacial timescale. Calculated values of δ18Osw-ss reflect a more saline condition during high local summer insolation (SI) periods. Such correspondence between δ18Osw-ss and local SI in the WPWP may reflect complex interaction between ENSO and monsoon, which was stimulated by changes in solar irradiance and their influence on the local hydrologic cycle. This then caused a striking reorganization of atmospheric circulation over the WPWP.