1059 / 2024-09-20 10:11:21
Small-scale nonlinear internal waves generated in a front system
small-scale nonlinear internal wave,front,HiSEA-1
Session 70 - Internal Waves and Ocean Mixing
Abstract Accepted
In previous studies, researchers reported a rare natural situation where gravity flow invades two vertical shear fluids to generate ISWs（Bourgault et al. 2016）， with few reports analyzing the process of internal wave generation by oceanic fronts. However, this internal wave generation mechanism and its associated dynamic processes hold significant importance for mixing, energy transfer, and instability processes in front-dominated regions. Benefiting from the high-resolution synthetic aperture radar satellite, HISEA-1, this study identifies nonlinear internal waves at the density double fronts of the Taiwan Strait. The spatial scale of the internal waves is too difficult to detect with previous observation methods, such as high-resolution true-color images. By analyzing the dynamic characteristics of these internal waves, it was inferred that they were locally generated. The study also examined the hydrological characteristics of this sea area (e.g., temperature, salinity, density, buoyancy frequency, current field, wind field) and the changes in front characteristics (e.g., asymmetry, three-dimensional spatial variation over time), linking the generation of internal waves to the variation of the fronts. Through sensitive experiments using numerical simulations, the study validated that the characteristics of the fronts in this area provide the conditions necessary for internal wave generation. This work reports the discovery of small-scale internal waves near the fronts in the Taiwan Strait, which are difficult to observe, and connects the generation of these waves to the unique density-double fronts in this region. It put forward a fresh mechanism of nonlinear internal wave generation near fronts in coastal oceans, laying a foundation for the diversity of internal wave dynamics and generation mechanisms in China's nearshore areas. In addition, this study combines the characteristics of global frontal distribution and previous studies on the mechanism of frontal internal wave generation in other sea areas, which enhances the generalizability of the mechanism and is of great value in analyzing and predicting internal wave generation at fronts in different global ocean regions.