Upper ocean water masses and transports in the Western Tropical Pacific (165°E)

As part of the international TOGA program, the ORSTOM Center in Nouméa (New Caledonia) initiated in January 1984 a series of semi-annual cruises along the 165°E meridian from 20°S to 10°N, across the equatorial current system of the western Pacific. This paper presents an analysis of the first six hydrographic (0-1000 m) and current (0-600 m) sections. A detailed description of "typical" January 1986 vertical structures of temperature, salinity and zonal measured velocity is offered. Differences are noted with structures previously obtained in the Tropical Pacific. Compared to the Central and Eastern Pacific, the 165°E data set evidences a much weaker equatorial upwelling and deeper surface isothermal layer and subsurface currents. Compared to the few Western Pacific measurements, the two speed cores of the Equatorial Undercurrent (EUC) previously reported at 100 and 200 m are not observed here. Special attention is given to the eastward equatorial jet (2°S-2°N; 0-75 m) measured in January 1985 when westerly winds were present from the north of New Guinea to 160°