Late Quaternary upper-water column structure in upwelling areas of the South China Sea

Based on a quantitative analysis of planktonic foraminifera in two gravity cores (17928 and 17954), the history of the upper-water structure of the ea stern and western slopes of the South China Sea (SCS) over the last 220 Ka was reconstructed using the transfer function technique. Our results show t hat lower sea surface temperature (SST) and shallower depth of thermocline (DOT) exist at Core 17928, off Luzon, in the glacial periods; on the contra ry, the same situation turned up in the interglacial at Core 17954, off Vie tnam. These changes of the upper-water column structure in the two areas ar e induced by coastal upwelling, which in turn is driven by monsoons, namely , winter monsoon leads to upwelling at the eastern slope, and summer monsoo n gives birth to upwelling on the western slope. Moreover, the intensity of upwellings is also closely related to the evolution of the East Asian mons oon. Therefore, we assume that the changes of the upwelling in the two site s indicate strengthenning of winter and summer monsoon during the glacial a nd interglacial periods, respectively.