Interannual variability of South China Sea winter circulation: response to Luzon Strait transport and El Niño wind

Abstract

The El Nino wind and Luzon Strait transport are important factors modulating the interannual variability of the southern and northern South China Sea (SCS) winter circulation, respectively. The joint effect of El Nino wind and westward Luzon Strait transport drives a dipolar gyre with an anticyclonic (cyclonic) circulation anomaly in the southern (northern) SCS, which enhances the cross-basin current that connects the SCS western boundary current with the eastern boundary of the SCS around the Mindoro Strait, and then effectively modulates the interannual variability of Mindoro Strait transport. An extreme El Nino and large Luzon Strait intrusion occurred in winter 2015/16, and mooring observations and remote sensing data confirmed the presence of an intense dipolar gyre. This resulted in an extreme eastward cross-basin current and outward SCS Mindoro Strait transport anomaly in 2015/16.