The inversion of remote sensing signatures of internal solitary waves (ISWs) can retrieve dynamic characteristics in the ocean interior. However, the presence of ubiquitous large‐amplitude ISWs poses challenges to the commonly used weakly nonlinear methods for parameter retrieval. Through laboratory experiments, we establish a relationship between surface features and internal characteristics of ISWs by the remote sensing imaging mechanism. The results demonstrate that strong nonlinearity significantly influences the retrieval of ISWs, primarily manifested in the calculation of wave‐induced velocities and the applicability of ISW solutions. A fully nonlinear model Dubreil–Jacotin–Long equation is used in the retrieval and has been tested under different conditions. Mooring observations indicate that the determination of ISW parameters from satellite images is affected by the complexity of in situ stratification, but additional remote sensing information such as surface velocities enables us to perform retrievals even if the real‐time measurement of pycnocline depth is not available.

Internal solitary waves (ISWs) typically manifest as soliton or wave trains in the ocean. Previous studies have extensively explored the dynamic properties of individual ISWs over topography. However, when the distance between successive ISWs in a wave train is less than a certain threshold, the interaction of multiple ISWs with the topography introduces mutual interference, leading to a more complex dynamical process. Therefore, this study established a numerical model based on OpenFOAM and analyzed the dynamical processes of two successive ISWs interacting with Gaussian ridges at different intervals. The findings reveal that the velocity field induced by the second wave (Wb) can transport and deform the vortex generated by the first wave (Wa) when Rab < 5 (Rab=Dab/Lw, where Dab is the distance between two ISWs, and Lw is the half-amplitude width). Additionally, the background field variation induced by Wa affects the shoaling and breaking of Wb. Particularly, when Rab < 3, the energy radiated to both sides of the ridge varies markedly with changes of Rab. The reflected leading wave of Wa is strengthened, while the transmitted leading wave of Wb is weakened, transferring energy to the transmitted trailing wave of Wa(the peak occurs at Rab=2.52). The interaction between the two waves not only modifies the energy structure but also distinguishes the variation in the dynamics of the bottom boundary layer from that of a single ISW. Notably, the negative bottom shear stress extremes induced by Wb are significantly enhanced, with the maximum value increasing by about 60%.

The remote sensing inversion of internal solitary waves (ISWs) enables the retrieval of ISW parameters and facilitates the analysis of their spatial variability. In this study, we utilize continuous optical imagery from the FY-4B satellite to extract real-time ISW propagation speeds throughout their evolution from generation to shoaling. ISW parameters are retrieved in the northern South China Sea based on the quantitative relationship between sea surface current divergence and ISW surface features in optical imagery. The inversion method employs a fully nonlinear equation with continuous stratification to account for the strongly nonlinear nature of ISWs and uses the propagation speed extracted from continuous imagery as a constraint to determine a unique solution. The results show that as ISWs propagate from deep to shallow waters in the northern South China Sea, their statistically averaged amplitude initially increases and then decreases, while their propagation speed continuously decreases with decreasing depth. The inversion results are consistent with previous in situ observations. Furthermore, a three-day consecutive remote sensing tracking analysis of the same ISW revealed that the spatial variation in its parameters aligned well with the abovementioned statistical results. The findings provide an effective inversion approach and supporting datasets for extensive ISW monitoring.

Internal solitary waves (ISWs) induce convergence and divergence of sea surface currents, manifesting as alternating bright-dark stripes in optical and synthetic aperture radar (SAR) images. Although the relationship between ISWs surface features in SAR images and sea surface currents has been extensively explored, it hasn’t been clearly quantified in optical images. This study contrasts surface features of the same ISWs using optical and SAR images with short time intervals, and statistically analyzes the 450 ISW stripe widths determined by the distance between the brightest and darkest points in the image. The results demonstrate that ISW surface features in optical and SAR images differ, with the stripe widths of SAR images being 0.83 times those of optical images. Laboratory experiments simulating surface features in optical and SAR images exhibit a consistent quantitative relationship with remote sensing results, and this difference is primarily attributed to the free surface displacement induced by ISWs.