Study on the circulation and water masses in the Northwest Pacific Ocean Using ARGO profiling floats

Xu Jianping 1,2 Liu Zenghong 1,2 Sun Chaohui 1,2 Zhu Bokang 1

1 Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310021, China
2 Key Lab. of Ocean Dynamic Processes and Satellite Oceanography, State Oceanic Administration. Hangzhou 310012, China

The main circulation and water masses in the area of northwest Pacific Ocean are studied using the drafting trajectory, temperature and salinity data obtained by ARGO profiling floats. Research shows that the main circulation in this area consists of the Subtropical Countercurrent (STCC), North Equatorial Current (NEC) /Equatorial Countercurrent (ECC), Kuroshio Current (KC), and the Mindanao Current (MC). It also indicates that SCC and NEC/ECC all have the characteristics of deep flow, for the evidence of them could be seen in the depth of 1500m. Near the offshore area east of Philippines, the flow field the NEC presents a complex structure, of which may be related to the bifurcating of the current in this area. The T - S relation in this region indicates there exist 8 water masses: they are the North Pacific Tropical Surface Water (NPTSW), North Pacific Subsurface Water (NPSSW), North Pacific Subtropical Water (NPSTW), North Pacific Intermediate Water (NPIW), North Pacific Deep Water (NPDW) and Equatorial Surface Water (ESW), and the South Pacific Subsurface Water (SPSSW) and South Pacific Intermediate Water (SPIW). It is the growth and decline of those water masses, the atmospheric circulation, and the air-sea interaction, that result in peculiar weather/sea anomaly phenomena such as typhoon, warm pool, and EL Nino/La Nina.