CURRENT STRUCTURE AND ITS VARIATION IN THE EQUATORIAL AREA OF THE WESTERN NORTH PACIFIC OCEAN

Based on the current measurement data from the R/V Ryofu Maru of JMA in the equatorial area along 137°E (1972-83) and 155°E (1972-79) the structures of the zonal velocity of the Equatorial Undercurrent (EUC) and the North Equatorial Countercurrent (NECC) and their variations are systematically analyzed in detail.At 155°E, the current at the equator and 100-300 m depth was a typical eastward EUC, it intensified in 1973-75, i.e., in the non-El Nino period. While the corresponding current at 137°E was mostly westward, and the origin of the EUC shifted to north of the equator around 0.5-1.5°N owing to the influence of the New Guinea Coast. The EUC origin disappeared in early July, 1982. Comparing with the EUC disappearance at 159°W, the average speed of an eastward travelling wave would be~1.1m/s.The velocity core of the NECC at 137 E generally shifted northward in winter and southward in summer, and was stronger in summer and weaker in winter. The fluctuations of the NECC were closely related to thos