Association of the Sulu Sea surface circulation with the South China Sea

Fifteen years of satellite altimetry data are used to study the seasonal and year-to-year variabilities of the surface circulation in the Sulu Sea (SS) and its association with the South China Sea (SCS) based on the Singular Value Decomposition method. The first seasonal mode in the SS reveals a basin-scale anticyclonic/cyclonic circulation, and the second seasonal and first interannual modes reveal a weak basin-scale anticyclonic/cyclonic meander flow from the Mindoro Strait to the Sibutu Passage. There is a high correlation of the SS circulation with that from the Mindoro Strait to the Balabac Strait in the southeastern SCS, which may be associated with the following three factors, first, the water exchange of the SS with the SCS via the Mindoro and Balabac straits; second, the oceanic responses to almost the same and synchronous seasonal variations of wind forcing; and third, the seasonal steric change between the SS and the southeastern SCS. The interannual SS circulation is also quite coherent with ENSO variability signal.