南海北部次表层盐度的变化及其与北赤道流分叉点的关系

吕宋海峡是南海与外界水交换的重要通道,黑潮作为北太平洋最强的1支西边界流,在经过吕宋海峡时会对南海北部的环流和环境产生重要影响。本文用1991—2011年期间CTD断面实测资料和高度计资料,提取23.0~25.5 kg/m³等密度面之间的盐度极大值,研究了南海北部不同年月盐度极大值变化、黑潮入侵方式与强弱,以及盐度极大值变化与北赤道流分叉点南北移动的关系,结果表明:(1)黑潮入侵南海方式多样,既有分支形式,也有弯曲、流套形式。(2)不同年月间,黑潮入侵南海的强弱存在较大差别,120°E断面的次表层盐度极大值的变动可超过0.3。(3)北赤道流分叉点位置的南北变动对黑潮入侵南海的强弱具有重要影响:北赤道流分叉点位置偏北,黑潮入侵南海较强;北赤道流分叉点位置偏南,则黑潮入侵相对较弱。

The variation of subsurface salinity in northern South China Sea and its relationship to the bifurcation of the North Equatorial Current

Luzon Strait is an important water exchange channel between South China Sea and Philippine Sea. As a famous western boundary current in the North Pacific, the Kuroshio has an important impact on the South China Sea circulation. In this research, we extracted the salinity-maximum at density of 23.0~25.5 kg/m³ and studied further the relation between the Kuroshio intrusion and bifurcation of the North Equatorial Current with CTD data of 1991—2011 and the satellite altimeter data. The results show that: (1) The ways of Kuroshio intrusion in SCS are diverse, including branch, bending and loop. (2) In different years, Kuroshio intrusion is quite different and the range of salinity-maximum can be more than 0.3 in the 120°E section. (3) The bifurcation of North Equatorial Current has a great effect on the intrusion of Kuroshio in South China Sea: When the bifurcation of North Equatorial Current moves to north, the Kuroshio intrusion in South China Sea is strong; when it moves to south, the Kuroshio intrusion is weak.