155°E赤道海流夏季基本特征

SUMMERY BASIC FEATURES OF THE EQUATORIAL CURRENTS AT 155°E

本文利用日本气象厅“凌风丸”1972—1979年夏季在155°E断面赤道附近的海流观测资料,分析了该断面上赤道流系夏季的基本特征及其与ElNio的关系。该断面上的赤道潜流相当稳定,它以赤道为中心,位于100—350m之间,平均输送量为31Sv,平均最大流速为73cm/s,而南赤道流和赤道表层流变化很大。文中以1975年6月和1976年6月两次观测资料为例,分析了1976—1977ElNio事件过程中南赤道流和赤道表层流的变化及其与西太平洋赤道地区大气环流的关系。

The current measurement data from the R/V Ryofu Maru of JMA in the equatorial area along 155°E in summer 1972-1979 are used to reveal summery basic features of the equatorial currents at 155°E and their relationship to El Nino events.On the average, the Equatorial Undercurrent (EUC) at 155°E is very stable both in position and strength. It's centred at the equator and limited between 2°N-2°S, 100-350 m depth The average transport is 31 Sv and the average maximum zonal velocity component is 73 cm/s. The South Equatorial Current (SEC) and the surface current above the EUC varied greatly-In June 1975 i.e. the summer before 1976-1977 El Nino event, the SEC was anomalously strong, it crossed the equator and extended to 2°N, the transport between 2°N-2°S reached at 12 Sv, while in June of 1972 and 1976,i.e. the summer of El Nino year, it was anomalously weak and shrinked back south of 2°S, the transport north of 2°S fell down to only 1 Sv and 3.7 Sv, respectively. In contrast to the SEC, the surface current above the EUC flowed toward east in June of 1972 and 1976, but mostly westward in June 1975. The eastward transport of the surface current between 2°N-2°S in June of 1972 and 1976 was 15 and 17 Sv, respectirely, but only 2 Sv in June 1975. By the comparing the variations of the equatorial currents discussed above with the variations of wind, it was found that in the post and pre-El Nino periods of 1972-1973 and 1976-1977 the variations of the equatorial currents at 155癊 were closely related with the anomlous variations of wind in the northwestern Pacific Ocean over 0°-10°N, 140°-180°E.