Impact of the South China Sea Throughflow on the Pacific Low-Latitude Western Boundary Current: A Numerical Study for Seasonal and Interannual Time Scales

Prior studies have revealed that, as a part of the Pacific tropical gyre, the South China Sea throughflow (SCSTF) is strongly influenced by the Pacific low-latitude western boundary current (LLWBC). In this study, ocean general circulation model (OGCM) experiments with and without connection to the South China Sea (SCS) were performed to investigate the impact of the SCSTF on the Pacific LLWBC. These model experiments show that if the SCS is blocked, seasonal variability of the Kuroshio and Mindanao Current becomes stronger, and the meridional migration of the North Equatorial Current (NEC) bifurcation latitude is enhanced. Both in seasonal and interannual time scales, stronger Luzon Strait transport (LST) induces a stronger Kuroshio transport combined with a southward shift of the NEC bifurcation, which is unfavorable for a further increase of the LST; a weaker LST induces a weaker Kuroshio transport and a northward shifting NEC bifurcation, which is also unfavorable for the continuous decrease of the LST.