考虑风暴潮强流剪切及地形坡度下的海浪－海流耦合强化作用研究

Storm surges and disastrous waves are hazardous natural phenomena caused by strong atmospheric disturbances, such as tropical cyclones (typhoons), extratropical cyclones and strong cold air gales, which would cause serious harm to coastal engineering, maritime transportation, fishing and maritime military activities, so either of them is one of the most harmful marine disasters nearby offshore sea area of China. The interaction between storm surges and waves is strong and complex. It is of great scientific significance and application value to study the enhancement effect and mechanism of storm surge-sea wave coupling. At present, the research on the mechanism of storm surge-wave coupling is inadequate. The topography is complex nearby the coastal of China, the coupling effect between strong shear current and sea wave is very strong during storm surges especially in the condition of the topographic gradient is large, but its physical mechanism is still not understood, which is a blank in the research field. Based on the unified linear wave theory, this study analyzed the enhancement effect of strong shear currents on wave amplitude and the modulation effect on wave dispersion relationship in dynamics, and established corresponding mathematical models. Typhoon storm surge process was selected to validate and evaluate these two storm surge shear currents and coastal waves coupling models which are present above. The purpose of this study is to reveal the coupling mechanism between strong storm surge shear current and ocean wave, and to quantitatively analyze its strengthening effect, continually so as to provide strong support for the prevention and mitigation of marine disasters in China.

风暴潮和灾害性海浪是由强烈大气扰动，如热带气旋（台风）、温带气旋和强冷空气大风等引起的灾害性自然现象，对沿岸工程、海上运输、海洋渔业和海上军事活动等造成严重危害，均是我国海域危害最大的海洋灾害之一。风暴潮和海浪相互影响，耦合加强作用显著且复杂，开展风暴潮-海浪耦合强化效应及作用机制研究具有重要科学意义和应用价值。当前风暴潮-海浪耦合作用机制研究并不成熟。我国近海海域地形复杂，地形坡度变化较大，风暴潮期间强剪切流与海浪的耦合作用强烈，但其物理机制尚不清楚，是该研究领域的空白。本研究基于“统一线性波”理论，从动力学角度，提出并分析强剪切流对波浪振幅的强化效应及对波浪频散关系的调制作用，建立相应的耦合数学模型；选取典型台风过程，对上述两个风暴潮强剪切流与近岸海浪耦合作用模型进行验证和评估。本研究旨在揭示风暴潮强剪切流与海浪的耦合作用机理，并定量分析其强化效应，为我国海洋防灾减灾工作提供科学支撑。

台风等极端天气条件下，海浪对沿岸工程、海上运输、渔业捕捞和海上军事活动等造成严重危害。海浪资料同化是改善海浪谱型精细化结构、提高海浪灾害预警水平的重要途径之一，但是近岸海域地形条件复杂，台风、风暴潮等多因子对近岸海浪具有耦合强化效应，粗网格的海浪资料同化结果并不能完全满足我国沿海区域海浪防灾减灾工作的需要。本研究基于具有我国自主知识产权的MASNUM海浪模式，提出动态采样法，利用Sentinel-1卫星SAR海浪谱资料，修正海浪谱结构，建立了高效的SAR海浪谱集合滤波同化模型。基于“统一线性波”理论，针对近岸复杂地形下的坡度变化，揭示底边界流场对波浪运动的激发机制，提出上层风海流剪切、底边界潮流剪切对波动振幅的强化数学模型。剪切流通过“共振作用”，使波动速度振幅发生显著变化。以2016年马勒卡台风为例，根据精细化地形数据，计算舟山附近海域的地形坡度，利用上述耦合作用模型，定量分析海浪强化作用，结果表明，底层垂向波动轨道速度振幅的改变量可以达到约0.4m/s。本研究有助于改进海浪的数值模拟效果，为海洋防灾减灾提供支持。