Interannual variability of the eastward current in the western South China Sea associated with the summer Asian monsoon

Abstract

The interannual variability of the eastward current in the western South China Sea (SCS) during the summer of 1993-2012 is examined with satellite altimeter data and Regional Ocean Modeling System (ROMS) model output. It is found that the meridional location of the eastward current displays apparent interannual variability. The core of the eastward current shifts between 10.7°N and 17.6°N with a standard deviation of 1.6°. Results from Sverdrup theory and ROMS experiments demonstrate a close dynamic linkage between the north-south migration of the eastward current and the SCS summer monsoon anomaly on the interannual time scale. When the summer monsoon has southwesterly (northeasterly) anomaly, the eastward current moves southward (northward). With the southward (northward) shift of the eastward current, the summer cold filament in the SCS moves southward (northward) as well. Key Points Interannual variability of the eastward current in the western SCS is robust Wind is responsible for the migration of the eastward current The eastward current has profound effects on the summer SST and Chl a