| MENG Qingjia,WANG Fan,LIU Na. 2011. Low-frequency variability of the North Equatorial Current bifurcation in the past 40 years from SODA. Acta Oceanologica Sinica, (3):14－19 |
| Low-frequency variability of the North Equatorial Current bifurcation in the past 40 years from SODA |
| Low-frequency variability of the North Equatorial Current bifurcation in the past 40 years from SODA |
| Received:July 29, 2010 Revised:November 05, 2010 |
| DOI：10.1007/s13131-011-0114-7 |
| Key words:North Equatorial Current bifurcation latitude interannual variation linear trend NEC-Mindanao Current-Kuroshio system |
| 中文关键词: North Equatorial Current bifurcation latitude interannual variation linear trend NEC-Mindanao Current-Kuroshio system |
| 基金项目:supported by the National Natural Science Foundation of China under contract No. NSFC 40890152 and the Knowledge Innovation Program of Chinese Academy of Sciences under contract No. KZCX2-YW-Q11-02. |
| Author Name | Affiliation | E-mail | | MENG Qingjia | Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
Key Laboratory of Ocean Circulation and Waves(KLOCAW), Chinese Academy of Sciences, Qingdao 266071, China
Graduate School of Chinese Academy of Sciences, Beijing 100039, China | | | WANG Fan | Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
Key Laboratory of Ocean Circulation and Waves(KLOCAW), Chinese Academy of Sciences, Qingdao 266071, China | fwang@ms.qdio.ac.cn | | LIU Na | National Marine Environmental Forecasting Center, Beijing 100081, China | |
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| Abstract: |
| 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. |
| 中文摘要: |
| 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. |
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