Inversion of Internal Solitary Wave Parameters in the Vicinities of Hainan Island Based on Remote Sensing Images

Internal solitary waves (ISWs), a prevalent hydrodynamic process in the global ocean, play a significant role in oceanic material transport, energy transfer, and marine engineering activities. Based on multi-source Synthetic Aperture Radar (SAR) satellite observations from 2005 to 2022, this study statistically analyzes ISW occurrences in the waters surrounding Hainan Island. The key findings are as follows: The spatial distribution patterns of ISWs in this region are preliminarily revealed. Using continuous timeseries remote sensing imagery combined with insitu measurements, the phase velocities of typical firstmode and secondmode ISWs are calculated. The Korteweg-de Vries (KdV), Benjamin-Ono (BO), and Taylor-Goldstein (T-G) equations are employed to invert these velocities, enabling the selection of suitable propagation models. Results indicate that ISWs near Hainan Island are primarily concentrated in the eastern and southern coastal areas of the island and along the Vietnamese coast, predominantly propagating westward and northwestward, together accounting for 63.7% of all cases. Phase velocities derived from sequential SAR images range from 0.19 to 0.49 m/s. A fieldobserved secondmode ISW exhibited a phase velocity of 0.31 m/s and an upperlayer amplitude of 10.5 m. Case studies further demonstrate that the selection of an appropriate inversion model should not rely solely on the wavelength-to-depth ratio; instead, it requires a comprehensive evaluation incorporating modal characteristics and the evolutionary stage of the waves under local topographic conditions.