长江口登陆台风增水数值模拟以“安比”为例

Numerical simulation on surge due to landfall of typhoon in the Yangtze Estuary: Ampil (No. 1810) as an example

  • 摘要: 1810号强台风“安比”是1990年以来直接登陆上海的最强台风,却并未诱发较大风暴增水。采用ERA-Interim数据集作为背景风场资料建立了双重嵌套的高分辨率风暴潮与天文潮耦合数学模型,研究了台风“安比”在长江口地区风暴潮增水特征及成因。结果表明:台风期间增水主要集中在长江口北支出口沿岸,而长江口南支在台风登陆后出现明显的减水过程,台风登陆位置导致了长江口南、北支增水分布的差异;移行风对台风路径右侧增水影响更大,除梯度风场的向岸风作用外,落潮期间移行风场的作用致使连兴港附近岸段风暴增水平均增幅26.8%;除台风强度外,台风路径也是影响长江口地区风暴增水大小的重要因素之一。

     

    Abstract: Typhoon Ampil, with limited magnitude of storm surge, is the most powerful tropical cyclone making landfall in the Yangtze Estuary since 1990. Based on the global atmospheric reanalysis data ERA-Interim, a high-resolution nested numerical model, coupled with storm surge and astronomical tide, is established to study the features of the storm surge induced by Typhoon Ampil, as well as the cause in the Yangtze Estuary. The results show that the storm surge is mainly distributed in the north branch of the Yangtze Estuary while an obvious set-down process is observed in the south branch after the landfall. The landing location of the typhoon clarifies the difference in surge patterns between the north and south branches. Besides the effect of the onshore wind of the gradient wind field, the translation wind has a greater impact on the surge on the right side of the typhoon track and is found to increase the average magnitude of the surge by an additional 26.8% along the coast of the Lianxinggang gauge station in ebb tide conditions. Apart from the intensity, the typhoon track is also one of the important factors affecting the magnitude of the storm surge in the Yangtze Estuary.

     

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