Analysis of internal wave characteristics based on SWOT data

Ocean internal wave occurs inside the seawater, which plays an important role in the transport of marine material and energy, also has great effect on the safety and concealment of underwater navigation. The Surface Water and Ocean Topography (SWOT) was launched in December 2022 and began publicly releasing data in November 2023, with its Ka-band radar interferometer (KaRIn) providing high spatial resolution two-dimensional sea surface elevation information. A small incidence angle backscattering model was established based on quasi-specular scattering model. The simulation results show that the internal wave stripe characteristics of small incidence angle are opposite to those of medium incidence angle SAR. The characteristics of internal waves in Sulu Sea and Celebes Sea were analyzed based on SWOT Level-3 data. The results show that internal waves can cause the sea surface height anomaly(SSHA) variation of 7-21cm and the backscattering amplitude(sigma0) variation of 6-11dB. The type of internal wave was confirmed by sigma0 stripe characteristics, and the SSHA variation characteristics were comparatively analyzed. The results show that the descending internal wave can bring about the sea level rise. This paper demonstrates the observation capability and advantages of SWOT for ocean internal waves.