Low-frequency variability of the North Equatorial Current bifurcation in the past 40 years from SODA  

作　　者：MENG Qingji WANG Fan LIU Na 

机构地区：[1]Key Laboratory of Ocean Circulation and Waves （KLOCAW）, Chinese Academy of Sciences, Qingdao 266071, China [2]Graduate School of Chinese Academy of Sciences, Beijing 100039, China [3]National Marine Environmental Forecasting Center, Beijing 100081, China

出　　处：《Acta Oceanologica Sinica》2011年第3期14-19,共6页海洋学报（英文版）

基　　金：supported by the National Natural Science Foundation of China under contract No.NSFC40890152;the Knowledge Innovation Program of Chinese Academy of Sciences under contract No.KZCX2-YW-Q11-02

摘　　要：The low-frequency variability of the North Equatorial Current （NEC） bifurcation during 1958 to 2001 was investigated with the Simple Ocean Data Assimilation （SODA） 2.0.2 dataset. In agreement with recent observations, the NEC bifurcation latitude （NBL） shifted northward as depth increases, from about 12.7°N near the surface to about 17.1°N at depths around 500 m for the annual average. This study reveals that the interannual variations of NBL, with five years period, mainly focused on the upper 500 m with amplitude increasing as depth increased. The NBL shifted southward in the past 40 years, which was more significant in the subsurface at more than -0.02°/a. The NBL manifests itself in the transports of NMK （NEC-Mindanao Current （MC）-Kuroshio） system in strong relationship with MC （0.7） and Kuroshio （-0.7）. The EOF analysis of meridional velocity off the Philippine coast shows that the first mode, explaining 62% of variance and 5 years period, was highly correlated with the southward shift of NBL with coefficient at about 0.75. The southward shift of NBL consists with the weakening of MC and strengthening of Kuroshio, which exhibited linear trends at -0.24Sv/a and 0.11Sv/a. Both interannual variation and trend of NBL were closely related to the variation of NMK system.The low-frequency variability of the North Equatorial Current （NEC） bifurcation during 1958 to 2001 was investigated with the Simple Ocean Data Assimilation （SODA） 2.0.2 dataset. In agreement with recent observations, the NEC bifurcation latitude （NBL） shifted northward as depth increases, from about 12.7°N near the surface to about 17.1°N at depths around 500 m for the annual average. This study reveals that the interannual variations of NBL, with five years period, mainly focused on the upper 500 m with amplitude increasing as depth increased. The NBL shifted southward in the past 40 years, which was more significant in the subsurface at more than -0.02°/a. The NBL manifests itself in the transports of NMK （NEC-Mindanao Current （MC）-Kuroshio） system in strong relationship with MC （0.7） and Kuroshio （-0.7）. The EOF analysis of meridional velocity off the Philippine coast shows that the first mode, explaining 62% of variance and 5 years period, was highly correlated with the southward shift of NBL with coefficient at about 0.75. The southward shift of NBL consists with the weakening of MC and strengthening of Kuroshio, which exhibited linear trends at -0.24Sv/a and 0.11Sv/a. Both interannual variation and trend of NBL were closely related to the variation of NMK system.

关 键 词：North Equatorial Current bifurcation latitude interannual variation linear trend NEC-Mindanao Current-Kuroshio system 

分 类 号：P732[天文地球—海洋科学] TP311.56[自动化与计算机技术—计算机软件与理论]