Studying of oceanic internal wave spectra in the Northeast South China Sea from seismic reflections
南海东北部海洋内波的反射地震研究

Extensive researches about internal waves are mostly from vertical profile observations; however, there are rare in-situ observation data to study horizontal characteristics of internal waves. Compared with the traditional physical oceanographic methods, reflection seismology has several advantages, such as high lateral resolution and the ability of imaging a large ocean profile in short time. Therefore, it is a promising observation technique for internal wave studies, which may make up the defects of traditional observation methods. Results from the reprocessing of a long multi-channel seismic profile in the northeastern margin of the South China Sea reveal clearly coherent undulating reflectors associated with internal waves in the water column. Horizontal wave number spectra of undulating reflectors are calculated and compared with the Garrett-Munk tow spectrum of oceanic internal wave displacements (GM76 spectrum). The results show that internal wave horizontal wave-number spectra are generally consistent with the theoretical GM76 spectrum. However, there are differences in amplitudes and slopes in the low and high wave-number regions between the calculated and theoretical spectra, which are considered to be associated with strong interaction between the internal tides and the complex seafloor topography, and internal wave breaking, etc.