| 基于拉格朗日拟序结构的吕宋海峡表层水交换研究 |
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| 引用本文： | 郑哲昊,庄伟,胡建宇,吴泽轮,刘长建.基于拉格朗日拟序结构的吕宋海峡表层水交换研究[J].海洋学报(英文版),2020,39(11):21-32. |
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| 作者姓名： | 郑哲昊 庄伟 胡建宇 吴泽轮 刘长建 |
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| 作者单位： | 厦门大学海洋与地球学院，近海海洋环境科学国家重点实验室，厦门，361102;厦门大学海洋与地球学院，近海海洋环境科学国家重点实验室，厦门，361102;南方海洋科学与工程实验室（广东省珠海），珠海，519082;厦门大学海洋与地球学院，近海海洋环境科学国家重点实验室，厦门，361102;特拉华大学和厦门大学联合遥感实验中心，特拉华州，19716;自然资源部南海调查技术中心，广州，510300 |
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| 基金项目： | The National Key Research and Development Program of China under contract No. 2016YFA0601201; the National Natural Science Foundation of China under contract Nos 91858202, 91958203, 41730533 and 41776003. |
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| 摘 要： | 黑潮通过吕宋海峡入侵南海呈现明显的瞬态特征。以往的研究通常将黑潮在吕宋海峡附近的流态分为几种不同类型。本文基于表层地转流计算得到的有限时间李雅普诺夫指数场（FTLE），展示了拉格朗日视角下的吕宋海峡上层水交换特征。从FTLE场提取的拉格朗日拟序结构（LCSs）很好地识别了吕宋海峡附近的典型流态和旋涡活动。此外，这些LCSs还揭示了吕宋海峡周围复杂的输运路径和流体域，这些特征得到了卫星跟踪浮标轨迹的验证，且从流速场中是无法直接识别的。FTLE场显示，吕宋海峡附近表层水体的输运形态主要可分为四类。其中，黑潮直接向北流动的“跨越”形态和顺时针旋转的“流套”形态的发生频次明显高于直接进入南海的黑潮分支“渗入”形态和南海水流出至太平洋的“外流”形态。本文还进一步分析了黑潮在吕宋海峡处的涡旋脱落事件，突出强调了LCSs在评估涡旋输运方面的重要性。反气旋涡旋的脱落个例表明，这些涡旋主要源自黑潮“流套”，涡旋脱落之前可有效地俘获黑潮水。LCS所指示的输运通道信息有助于预测最终被反气旋涡所挟卷水体在上游的位置。而在气旋涡的形成过程中，LCS的分布特征表明，大部分气旋涡并未与黑潮水的输运路径相连通。因此，气旋涡对从太平洋到南海的上层水交换的贡献较小。
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| 关 键 词： | 拉格朗日拟序结构 黑潮 吕宋海峡 输运路径 粒子追踪 |
| 收稿时间： | 2020/5/1 0:00:00 |
Surface water exchanges in the Luzon Strait as inferred from Lagrangian coherent structures |
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| Zheng Zhehao,Zhuang Wei,Hu Jianyu,Wu Zelun,Liu Changjian.Surface water exchanges in the Luzon Strait as inferred from Lagrangian coherent structures[J].Acta Oceanologica Sinica,2020,39(11):21-32. |
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| Authors: | Zheng Zhehao Zhuang Wei Hu Jianyu Wu Zelun Liu Changjian |
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| Institution: | 1.State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China2.Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China3.Joint Center for Ocean Remote Sensing, University of Delaware-Xiamen University, Newark, DE 19716, USA4.South China Sea Marine Survey and Technology Center, Ministry of Natural Resources, Guangzhou 510300, China |
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| Abstract: | This study presents a Lagrangian view of upper water exchanges across the Luzon Strait based on the finite-time Lyapunov exponents (FTLE) fields computed from the surface geostrophic current. The Lagrangian coherent structures (LCSs) extracted from the FTLE fields well identify the typical flow patterns and eddy activities around the Luzon Strait. In addition, they reveal the intricate transport paths and fluid domains, which are validated by the tracks of satellite-tracked surface drifters and cannot be visually recognized in the velocity maps. The FTLE fields indicate that there are mainly four types of transport patterns near the Luzon Strait; among them, the Kuroshio northward-flowing “leaping” pattern and the clockwise rotating “looping” pattern occur more frequently than the “leaking” pattern of the direct Kuroshio branch into the SCS and the “outflowing” pattern from the SCS to the Pacific. The eddy shedding events of the Kuroshio at the Luzon Strait are further analyzed, and the importance of considering LCSs in estimating transport by eddies is highlighted. The anticyclonic eddy (ACE) shedding cases reveal that ACEs mainly originate from the looping paths of Kuroshio and thus could effectively trap the Kuroshio water before eddy detachments. LCSs provide useful information to predict the positions of the upstream waters that finally enter the ACEs. In contrast, LCS snapshots indicate that during the formation of cyclonic eddies (CEs), most CEs are not connected with the pathways of Kuroshio water. Hence, the contribution of CEs to the surface water exchanges from the Pacific into the SCS is tiny. |
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| Keywords: | Lagrangian coherent structures (LCSs) Kuroshio Luzon Strait transport pathways particle tracking |
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