The correlation of the surface circulation between the Western Pacific and the South China Sea from satellite altimetry data

Abstract

Fifteen years of satellite altimetry data are used to study the correlation of the surface circulation between the Western Pacific and the South China Sea (SCS) based on the Singular Value Decomposition method. There is a high correlation between the circulation of the SCS and the North Equatorial Current (NEC) current system. In summer/winter, the sea surface height (SSH) of the NEC rises/falls while the two SCS sub-basin-scale eddies are anti-cyclonic/cyclonic. It reveals both annual and eight-year variability in the circulation. The NEC bifurcation latitude is highly correlated with the water exchange via the Luzon Strait (LS) and the Luzon Cyclonic Eddy (LCE). When the NEC bifurcation latitude moves northward/southward, the water exchange via the LS increases/reduces and the SSH of the LCE reduces/increases. The annual mean number of eddies propagating westward into the Western Pacific within (121∼135°E, 15∼25°N) is about 18∼27 with a 3∼4 year fluctuation. No eddy is found to propagate into the SCS via the LS from the Western Pacific, and the eddy density is defined to show the different distributions between the cyclonic eddies (CEs) and anti-cyclonic eddies (ACEs) in the north-eastern SCS and north-western Pacific, and the difference in the concentration and interaction with the Kuroshio between the CEs and the ACEs is also discussed. The monthly statistics of the number, tracks, lifetimes and moving speeds etc. of the eddies in the north-western Pacific are also shown.