The interaction between internal waves and submarine seamounts is three-dimensional (3D). In this work, we conduct laboratory experiments to investigate the role of the three-dimensional seamount on the reflection of internal waves. Experimental results show that the energy of internal waves is focused after the reflection and the phase of the internal wave front become curved. The energy of the focusing region was nearly 2 times as that of the scattering region. There is a strong internal wave induced mean flow whose strength is nearly as high as 50% of that of the reflected internal wave. The mean flow was generated by the variation of the velocity amplitude in both the x axis and y axis. These results indicate that the reflection from the 3D seamount could lead to a complex spatial distribution of the internal wave and a different energy conversion process.

Reflection of the K₁ internal tides (ITs) in the northern South China Sea (SCS) is investigated using a high‐resolution three‐dimensional numerical model. The simulated results indicate that the westward K₁ ITs generated at the Luzon Strait (LS) first impact the continental slope in the northern SCS, and thereafter are reflected. There is a total of 0.31 GW of K₁ energy that are reflected, suggesting a weak reflection considering 3.54 GW of westward K₁ energy from the LS. Two reflected K₁ beams are revealed. The southeast one is the more energetic and can propagate across the deep basin, agreeing with that extracted from satellite altimeter data. The eastward one propagates toward the LS, but it is absent in altimeter results because of its lower intensity. Both the two reflected beams are radiated from the supercritical region in shallow water. Different from the incident waves that are dominated by mode‐1, the reflected waves exhibit a multimodal structure. Contribution of high modes to reflected waves is comparable to that of mode‐1. Moreover, modal content is different for the two reflected beams, with higher proportion of high‐mode energy flux for eastward reflected beam. In contrast to the K₁ ITs, no remarkable reflected O₁ ITs are detected from either simulated or altimeter results. This is due to the weak generation of O₁ ITs at the LS, which leads to less O₁ energy reaching the continental slope. The results of this work can provide essential insight on IT dynamics in the SCS.

The effects of Surface Solitary Waves (SSWs), which are created by Internal Solitary Waves (ISWs), on optical imaging were investigated in this paper. We explored the connection between SSWs and optical images using simulations and experiments with calm water surface conditions. An experimental platform was built in a controlled laboratory environment where optical images and in‐situ wave data could be gathered simultaneously. SSWs created by different ISWs were successfully observed. The optical images revealed inverse bright and dark patterns for different ISW types (depression or elevation type). Based on theories and experimental results, simulation models of the ISWs and SSWs were built in Unigraphics NX. Using the illumination simulation function of Light Tools, the reason underlying the reversed patterns was explained by the irradiance distribution. Both the experiment and simulation indicated that the SSWs created by the ISWs affected the characteristics of optical images. To further explore how SSWs affect imaging, 16 experiments were designed to investigate the effects of ISW type, amplitude, and water density ratio. It is found that the relationship among the SSW amplitude, ISW amplitude, and density ratio was consistent with earlier studies. The relationships between imaging characteristics (grayscale differences and pattern widths) and the two types of SSWs were consistent.

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) in the South China Sea (SCS) are considerably modulated by the background currents. In this study, a three-dimensional high-resolution non-hydrostatic model is configured to investigate how the Kuroshio influences the generation and evolution of ISWs in the northern SCS. Three runs are conducted, including one control experiment without the Kuroshio and two sensitivity experiments with the Kuroshio in different paths. In the Luzon Strait (LS), the Kuroshio reduces the westward baroclinic energy flux radiated into the SCS, resulting in weakened ISWs. In the SCS basin, the background currents further refract the ISWs. With the leaping Kuroshio, the A-waves have longer crest lines but lower amplitudes compared with those in the control run. In contrast, the B-waves are less affected by the leaping Kuroshio. In the presence of looping Kuroshio, the wave refraction caused by the intrusion currents in the SCS basin results in the weakest amplitudes and energy but the widest crest lines of ISWs. Moreover, the energy of the A-waves exhibits double-peak structure along the crest lines. The crest lines of the B-waves extend to 19.5° N, which are more south than those in summer. These results highlight the importance of the Kuroshio on the 3D features of ISWs in the SCS.