Millennial-scale climate variability of the low-latitude Pacific during the last glacial: Evidence from faunal records and hydrographic gradients

For better understanding of internal feedback in the tropical atmosphere-ocean and the coupling between the tropical and extra-tropical system in the basin-wide Pacific during the last glacial, here we reconstruct high-resolution faunal sea surface temperature (SST) estimates around the South China Sea (SCS) and eastern equatorial Pacific (EEP). Our results indicate that a significantly intensified cold SST condition in the EEP (ODP 1240) is associated with enhanced subpolar and/or Eastern Boundary Current components, whereas previous Site 1240 δ13C record reveals that a gradually reduced Equatorial Undercurrent Current (EUC) is from the last 160 kya. This implied that EUC waters are gradually substituted for the northward incursions of the subpolar and/or EBC currents, particular for the last 75 kya. As compared with millennial-scale climate archives around the East Asia and the western Pacific Ocean, SSTs at the SCS and the EEP reveal profound coolings in the Heinrich Event (HE) 3 and HE6. By exploring hydrographic gradients across the tropical Pacific, we further speculate that latitudinal movements of atmospheric (i.e., the ITCZ and east Asian monsoon) and oceanographic (i.e. subpolar water mass/Peru Chile Current system) circulation would play a more active role and transfer millennial to orbital-scale hydrographic changes during the last glacial.