Impact of Remote Internal Tides on Local Generation in the South China Sea

Using the CROCO(Coastal and Regional Ocean Community Model) numerical model, comparative experiments with and without internal tide radiation from the Luzon Strait (LS) are conducted to systematically investigate the impact of remote K1 internal tides on locally generated internal tides in the South China Sea (SCS). Results show that westward internal tides from the LS significantly enhance the westward energy flux in the SCS. The tidal beams develop multi-path structures through geostrophic refraction and topographic scattering, propagating across the entire SCS basin to reach the Vietnamese coast. The reorganization of propagation pathways modulates local energy conversion processes. Remote internal tides elevate conversion efficiency at generation sites by amplifying the bottom perturbation pressure amplitude, while simultaneously altering the phase relationship between perturbation pressure and barotropic tidal flow, resulting in negative conversion in certain regions. This indicates that both amplitude amplification and phase restructuring jointly govern the spatial distribution of conversion rates. As conversion rates increase, more energy dissipates at supercritical topography, with the most pronounced enhancement occurring near Dongsha, which lies along the primary propagation pathway. In the deep basin, modal scattering at seamounts and subsequent high-mode dissipation constitute an additional pathway for progressive energy attenuation of the remote internal tides.