A mid-depth front separating the South China Sea water and the Philippine sea water

In order to understand the influence of the South China Sea (SCS) water on the Kuroshio, and to study the dissolved carbonate system, we participated in six WOCE cruises aboard R/V Ocean Researcher 1. The areas studied were the northeast South China Sea and the West Philippine Sea near the Luzon Strait. Temperature, salinity, pH, alkalinity and total CO₂ were measured. Our data indicate that, although the Kuroshio and the SCS waters flow in and out of the Luzon Strait near surface, the SCS water seems mainly to flow out of the SCS at mid-depth. There exists a mid-depth front near 122°E between 350 and 1350 m in all seasons and years that we studied. The water mass between 350 and 1350 m east of the front belongs to the West Philippine Sea proper water, while on the west is the mixed water of the South China Sea and the West Philippine Sea.