北太平洋西边界流的低频变化特征

On low-frequency variations of volume transport of the Pacific western boundary currents

基于日本气象厅长时间序列的温、盐度再分析资料,利用动力计算方法分析了北太平洋西边界的北赤道流及其下游黑潮和棉兰老流流量的年际和年代际变化,并探讨了北赤道流变化的可能原因。结果表明,北赤道流和黑潮具有比较一致的年际和年代际变化,均在1976年前后发生了一次气候跃变,之后有长期偏强的趋势,而棉兰老流的年际和年代际变化则有所不同。特别是,北赤道流1976年之后增加的流量似乎大多进入黑潮,而流入棉兰老流的流量则减少。进一步的分析还表明,西传的Rossby波和棉兰老冷涡的变动可能对北赤道流的年际变化有重要影响。

The volume transports of the North Equatorial Current （NEC）,the Kuroshio （KC）,and the Mindanao Current （MC） along the Pacific western boundary were investigated through traditional dynamical method by using long-time and high-resolution data set. The results show that the volume transports of the NEC and KC exhibited similar distinct inter-annual and inter-decadal variations. Both of them experienced a climate jump in 1976 and bear obvious intensifying trends after 1976. In contrast,the transport fluxes of the MC transport is different from that of the NEC and KC. It seems that the increased volume of the NEC mostly flows into the KC rather than the MC af- ter 1976. The correlation analysis suggests that inter-annual variations of the NEC transport may be also greatly influenced by Rossby Wave and Mindanao cyclonic eddy.