Role of the South China Sea in Regulating the North Pacific Double-gyre System Using Two-layer Quasi-geostrophic Model

The role of South China Sea (SCS) in regulating the double-gyre system is investigated based on a two-layer quasi-geostrophic (QG) model. It is found that the SCS acts as a sink for both potential vorticity (PV) and energy in the Pacific-SCS system, which significantly weakens the Kuroshio and eastward jet (EJ) by 10%. At mesoscale timescale, the SCS is found to suppress the eddy activity in the Pacific Ocean by influencing the variability of relative PV transport and barotropic energy conversion term, while it promotes the low-frequency evolution of the Pacific circulation in the EJ extension region which is induced by the negative correlation between the inertia of the Kuroshio and the Kuroshio intrusion.