Using a coastal assimilation model, generation mechanism of unusually high sea level (UHSL) at the south coast of Japan in September 2011 is investigated. Both model results and tide gauge observations indicate that sea level rise associated with the UHSL event occurred twice in the middle and end of September. The first one, which is localized around the eastern part of the Seto Inland Sea, is caused by a cyclonic circulation in the Kii Channel formed as a result of northward migration of the Kuroshio axis toward Cape Shionomisaki. The second sea level rise, which is the main contributor to this UHSL event, is observed in wide areas not only at the south coast of Japan, but also at the coast of the Japan Sea. It is brought about by a coastal trapped wave (CTW) induced as a result of a fluctuation of the Kuroshio path to the south of the Boso Peninsula. The CTW with positive SSH anomalies propagates westward along the south coast of Japan, and then goes into the coast of the Japan Sea. Sensitivity experiments and a modal characteristic analysis indicate that the CTW is mainly characterized by the first mode baroclinic Kelvin wave. The phase speed for the first mode is calculated at 2.96 m s-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{-1}$$\end{document}, which compares well with that estimated by tide gauge observations.

中文翻译：

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2011 年 9 月由黑潮引起的日本南部海岸异常高的海平面

利用海岸同化模型，研究了 2011 年 9 月日本南部海岸异常高海平面 (UHSL) 的产生机制。模型结果和潮位计观测均表明，与 UHSL 事件相关的海平面上升在 9 月中旬和下旬发生了两次。第一个位于濑户内海东部附近，是由黑潮轴向北迁移至盐见岬而形成的纪伊海峡的气旋环流引起的。第二次海平面上升是这次 UHSL 事件的主要贡献者，不仅在日本南部海岸，而且在日本海沿岸的广大地区都可以观察到。它是由房总半岛南部的黑潮路径波动引起的沿海困波（CTW）引起的。具有正 SSH 异常的 CTW 沿日本南海岸向西传播，然后进入日本海沿岸。灵敏度实验和模态特征分析表明，CTW 主要以第一模式斜压开尔文波为特征。第一种模式的相位速度计算为 2.96 m s-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage {mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{-1}$$\end{document}，这与潮汐计观测估计的结果相当。具有正 SSH 异常的 CTW 沿日本南海岸向西传播，然后进入日本海沿岸。灵敏度实验和模态特征分析表明，CTW 主要以第一模式斜压开尔文波为特征。第一种模式的相位速度计算为 2.96 m s-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage {mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{-1}$$\end{document}，这与潮汐计观测估计的结果相当。具有正 SSH 异常的 CTW 沿日本南海岸向西传播，然后进入日本海沿岸。灵敏度实验和模态特征分析表明，CTW 主要以第一模式斜压开尔文波为特征。第一种模式的相位速度计算为 2.96 m s-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage {mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{-1}$$\end{document}，这与潮汐计观测估计的结果相当。灵敏度实验和模态特征分析表明，CTW 主要以第一模式斜压开尔文波为特征。第一种模式的相位速度计算为 2.96 m s-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage {mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{-1}$$\end{document}，这与潮汐计观测估计的结果相当。灵敏度实验和模态特征分析表明，CTW 主要以第一模式斜压开尔文波为特征。第一种模式的相位速度计算为 2.96 m s-1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage {mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{-1}$$\end{document}，这与潮汐计观测估计的结果相当。