Surface wave disturbance during internal wave propagation over various types of sea bottoms

In this study, we used a numerical model to simulate the propagation of internal waves (IWs) over various topographies, such as those with a flat bottom or bottom with a triangular trench or a ridge, and investigate the development, propagation, and dissipation mechanisms of IWs. Detailed evolution of IWs and vortices and their effects on the disturbance of the ocean surface were studied. The numerical results show that strong mixing and water exchange occur during IW propagation, resulting in severe convergence and dispersion, which lead to strong free surface flow and create noticeable free surface waves. The shapes of free surface waves and IWs have opposing orientations. In addition, there exists a close relationship between IWs and ocean surface waves, which may assist researchers in retrieving the amplitude of IWs by observing the behavior of free surface waves. The resonant interaction of IWs and surface waves was analyzed as IWs passed various types of sea bottom. The results indicate that IWs and surface waves move in the same phase, and the spatial variation of the waves shows that both wave types have the same wavelength.