| ENSO循环相联系的北太平洋低纬度异常西边界流 |
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| 引用本文： | 陈永利,赵永平,王凡,唐晓晖.ENSO循环相联系的北太平洋低纬度异常西边界流[J].海洋学报,2013,35(6):9-20. |
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| 作者姓名： | 陈永利 赵永平 王凡 唐晓晖 |
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| 作者单位： | 中国科学院 海洋研究所, 山东 青岛 266071;中国科学院 海洋环流与波动重点实验室, 山东 青岛 266071 |
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| 基金项目： | 国家重点基础研究发展计划项目（2012CB417401）;国家自然科学重点基金（40890152）;中国科学院战略先导性专项（XDA10010104）共同资助。 |
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| 摘 要： | 用SODA海洋同化和NCEP大气再分析资料,分析了热带太平洋次表层海温异常主要模态与北太平洋低纬度西边界流海域上层海洋环流和亚洲-北太平洋地区大气垂直和水平流场变化之间的关系,得到以下结果:（1） 在热带太平洋海洋次表层ENSO事件具有两种模态,二者组合构成ENSO循环。第一模态为ENSO成熟期,主要出现在冬季,第二模态为ENSO过渡期,主要出现夏季。（2） ENSO循环对北太平洋低纬度西边界流区上层海洋环流有重要影响。在El Niño发展期或La Niña 衰退期,该区出现气旋性异常环流,北赤道流（NEC）加强,NEC分叉位置北移,棉兰老海流（MC）加大,菲律宾以东黑潮（KC）减小,北赤道逆流（NECC）最强。在El Niño（La Niña）成熟期,该区气旋性（反气旋性）异常环流达最强,NEC最强（最弱）,NEC分叉位置最北（最南）,MC最大（最小）,KC最小（最大）,NECC减弱（加强）。在El Niño衰退期或La Niña发展期与El Niño发展期相反,该区出现反气旋性异常环流,由此导致相应流系异常发生反位相变化。（3） ENSO循环对北太平洋低纬度西边界流海域上层海洋环流的影响是通过ENSO事件期间热带太平洋热力状况异常改变上空大气环流来实现的。ENSO事件首先造成热带太平洋海洋热力状况异常,导致其上空对流活动异常,后者直接或间接通过“大气桥”能量传输引起相关地区大气环流场的变化,致使海面风应力场异常,进而强迫上层海洋环流场的相应变化。文章最后还分析了ENSO事件期间菲律宾附近异常反气旋或异常气旋性风场的产生和持续原因,讨论了北太平洋低纬度西边界流海域海气相互作用在ENSO循环中的贡献。
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| 关 键 词： | 北太平洋低纬度西边界流 ENSO循环 北赤道流分叉 棉兰老流 源区黑潮 |
| 收稿时间： | 2012/7/22 0:00:00 |
Low-latitude western boundary current anomalies in the North Pacific associated with the ENSO cycle |
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| CHEN Yongli,ZHAO Yongping,WANG Fan and TANG Xiaohui.Low-latitude western boundary current anomalies in the North Pacific associated with the ENSO cycle[J].Acta Oceanologica Sinica (in Chinese),2013,35(6):9-20. |
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| Authors: | CHEN Yongli ZHAO Yongping WANG Fan and TANG Xiaohui |
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| Institution: | Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;Key Laboratory of Ocean Circulation and Wave Studies, Chinese Academy of Sciences, Qingdao 266071, China |
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| Abstract: | Based on SODA ocean assimilation and NCEP atmospheric reanalysis data, relationships of the main modes of tropic Pacific subsurface ocean temperature anomalies with variations of the upper ocean circulation of the North Pacific low-latitude western boundary currents (NPLLWBC) and the Asian-North Pacific atmospheric vertical and horizontal flow fields are analyzed. Major results are summarized as follows:(1) The tropical Pacific subsurface ocean variabilities are dominated by two primary modes, which make up the ENSO cycle. The first mode, represents the ENSO mature phase, and mainly prevails in winter, while the second mode represents the ENSO transition phase, prevailing in summer.(2) ENSO cycle has major impact on the upper ocean circulation in the NPLLWBC areas. During the developing phase of El Niño events or decaying phase of La Niña events, anomalous cyclonic circulation evolves in this area, accompanied by strengthening of the North Equatorial Current (NEC), northward shift of the NEC bifurcation location, enhancement of the Mindanao Current (MC), weakening of the Kuroshio Current (KC) in its source region, and the strongest phase of the North Equatorial Countercurrent (NECC). During the mature phase of El Niño, the anomalous cyclonic circulation in this area reaches its strongest phase, with NEC also strongest, NEC bifurcation location northmost, MC strongest, KC weakest, and NECC weakened. Vice versa, during the decaying of El Niño or developing of La Niña, anomalous anti-cyclonic circulation appears in the area, the NEC weakens, NEC bifurcation location shifts southward, MC weakens while KC strengthens, and the NECC becomes weakest. During the mature phase of La Niña, the anti-cyclonic circulation anomalies become strongest, with NEC weakest, NEC bifurcation location southmost, MC weakest, KC strongest, and NECC strengthened. (3) The influence of ENSO cycle on the upper ocean circulation of NPLLWBC are mainly achieved through the change of atmospheric circulation in response to thermal condition anomalies in the tropical Pacific during ENSO events. The ENSO events first generate anomalous thermal conditions in the tropical Pacific Ocean, which lead to anomalous convection activities in the above atmosphere. The latter in turn alters atmospheric circulation field in related area directly or indirectly by energy transport through the "atmospheric bridge" resulting in anomalous sea surface wind stress fields, and thus forces corresponding variations in the upper ocean circulation. In the end of the paper, the reasons for generation and sustainment of the anomalous anti-cyclonic/cyclonic wind fields near Philippines during the ENSO events are also analyzed, and the contributions of air-sea interaction in the NPLLWBC areas to the ENSO cycle are discussed. |
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| Keywords: | North Pacific low-latitude western boundary currents ENSO cycle North Equatorial Current bifurcation Mindanao Current Kuroshio Current in source region |
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