南海是全球内孤立波最活跃的海域之一，不仅存在单个的内孤立波，也广泛发生两个内孤立波间的波-波相互作用。在一定条件下，波-波相互作用能产生第三个新的内孤立波，振幅也可以显著变大，甚至达到初始振幅的四倍。大振幅内孤立波及波-波相互作用不仅对海上油气平台、水下航行器等构成威胁，而且其失稳破碎时，会引起水体的混合，影响能量输运过程。目前的研究表明南海真实地形、地球旋转和背景流会影响单个内孤立波的演变，同时对其影响机制也有了一定程度的认知。然而，这三种因素如何影响南海内孤立波间波-波相互作用还不清楚，研究成果也十分稀少。因此，本项目拟以三维内波各向同性理论的推导和分析为主轴，结合数值模拟与观测资料，多角度同步交叉，研究真实地形、地球旋转和背景流对南海内孤立波间波-波相互作用的影响，认识波-波相互作用的演变过程，刻画演变的具体规律，揭示现象背后的物理机制。

The internal solitary waves in the South China Sea (SCS) region are among the largest and most frequently observed in the world’s oceans. Not only the single internal solitary wave, but also wave-wave interactions occur in the SCS. Under the specific circumstance, these wave-wave interactions can not only boost the amplitude in the junction point to be four times but also generate a third internal solitary wave. Large-amplitude internal solitary waves pose potential hazards on offshore drilling platforms, submarines etc. and their eventual breaking induces turbulent mixing, which plays an important role in the energy transport. Observations indicate that the interactions between two internal solitary waves are very common in the SCS. It is now recognized that realistic topography, the Earth’s rotation and background current have great impact on the evolution of a single internal solitary wave. Nevertheless, the research on the impact of these three factors on wave-wave interactions is rare. Thus, based on the derivation and analyses of an isotropic theory for 3D internal solitary waves, along with numerical simulations and oceanic observations, this project is focused on investigating the individual impact of realistic topography, the Earth’s rotation and background current on interactions between two internal solitary waves in the SCS, which could reveal the underlined dynamics on internal wave-wave interactions and promote our understanding on the internal solitary waves in the SCS, laying a solid foundation on the ultimate aim of prediction.