137°E断面北赤道流的结构特征和年际变化

摘要

The velocity structure and interannual variability of the North Equatorial Current (NEC) and its controlling mechanism were investigated based on the CTD data along the 137°E section obtained by Japan Meteorological Agency (JMA) from 1967 to 2009 and satellite altimetric sea surface height (SSH) data. The results show that the NEC is located between 8°N and 18°N, with a velocity core at 10°~12°N along the 137°E section. The EOF analysis revealed similar patterns in leading modes both in summer and winter, showing out-of-phase interannual variations for the southern and northern parts of the NEC. This phenomenon of the NEC may be controlled by abnormal cyclone and anticyclone circu-lation in the tropical western Pacific. The velocity filed in the NEC had different response to ENSO in summer compared to that in winter. In El Niño (La Niña) summer, the velocities in the upper and central NEC were strong (weak), while in El Niño (La Niña) winter, the velocities in the central and deep NEC were weak (strong).%基于日本气象厅在1967~2009年间获得的温盐深仪(CTD)资料以及美国提供的卫星高度计资料,分析了137°E 断面北赤道流(NEC)的结构特征和年际变化,并探讨了其年际变化的控制机制。结果表明,在137°E断面, NEC的平均位置位于8°~18°N,其流核出现在10°~12°N附近；无论冬季还是夏季, NEC的流速距平场都具有南、北向的反位相年际振荡特征,而这种南、北向的反位相振荡可能是由热带西北太平洋的气旋性和反气旋性异常环流所控制； NEC内部的流速对EI Niño-Southern Oscillation (ENSO)的响应也存在着明显的季节特征,其中,在El Niño(La Niña)期间的夏季, NEC中上部的流速增大(减小)；在El Niño(La Niña)期间的冬季, NEC中下部的流速减小(增大),而NEC南、北两侧的流速则增大(减小)。