Investigation of the influence of stratification and background currents on Internal Solitary Waves in the northern South China Sea based on the Wavefront model

Abstract

Internal Solitary Waves (ISWs) are nonlinear internal waves generated within vertically stratified oceans, characterized by large amplitudes and strong destructive capabilities. Previous studies have shown that background currents significantly affect the propagation process of ISWs. However, the background currents can also induce changes in stratification, and the specific manner in which they influence ISWs remains unclear. This study, based on the Wavefront model, independently investigates the effects of oceanic stratification and background currents on the nonlinear phase velocity, crest line morphology, and energy distribution of ISWs in the northern South China Sea. The results show that compared to stratification, background currents are more likely to alter the nonlinear phase speed of ISWs. The background currents also significantly alter the generation locations and propagation directions of ISWs. Furthermore, this study analyzes the propagation characteristics of ISWs under different Kuroshio circulation patterns and points out that the Kuroshio primarily regulates ISWs through background currents. The Wavefront model serves as a powerful tool for accurately forecasting ISWs in the northern South China Sea and holds great potential for studying other characteristics of ISWs.