斯里兰卡南部海域次重力波特征研究

次重力波在近岸水动力运动过程中起到重要作用，深入地了解次重力波对预防其引发的近岸灾害有着重要意义。结合波浪现场观测方法和数值模拟方法研究了斯里兰卡南部海域次重力波特征。短波和自由次重力波通过海浪谱模型WAVEWATCH III模拟，而约束次重力波通过二阶非线性理论模拟，数值模拟结果与现场观测结果对比吻合良好。研究结果表明，斯里兰卡南部海域大部分时间以自由次重力波为主；在强涌浪海况下（短波波高大于2.5 m，周期大于15 s）约束次重力波逐渐逼近自由次重力波甚至占主导地位；斯里兰卡大陆架极其狭窄，对涌浪的能量损耗作用极为有限，使得近岸面对强劲的涌浪及其伴生的次重力波的侵袭，增大了次重力波引发近岸水动力灾害的风险。

Research on infragravity wave characteristics in the southern sea of Sri Lanka

Infragravity (IG) waves play an important role in many coastal processes. A better understanding of IG waves is of importance to preventing coastal disasters caused by IG waves. IG wave characteristics in the southern sea of Sri Lanka are investigated by combining in-situ observations and spectral wave modeling. Short waves and free IG waves are simulated by the spectral wave model WAVEWATCH III, whereas the bound IG waves are modeled using the second-order nonlinear theory. A good agreement is found between the numerical results and observed data, validating the research method adopted in this work. Results show that free IG waves dominated the low-frequency waves most of the time, whereas bound IG waves enhanced during storms and even exceeded the free IG waves. The width of the continental shelf of Sri Lanka is extremely narrow such that the continental shelf has a very limited effect on reducing the swell energy. Strong swell and its associated IG waves attack the coasts of Sri Lanka, thereby increasing the risk of coastal hydrodynamic disasters caused by IG waves.