An internal wave investigation in the Bay of Bengal

Abstract So far, knowledge of internal waves in the Bay of Bengal is still limited, and there is a gap in understanding their propagation characteristics. Because of the stochastic nature of internal waves, there are few opportunities to observe internal waves through the surface field, and currently no internal waves have been observed from the surface in the Bay of Bengal. Recently, we captured a surface image of internal waves in the Bay of Bengal and matched the satellite image of internal waves with positional information. Subsequently, the evidence of the existence of internal waves was verified using Biogeochemical-Argo data and satellite images of the region where the internal waves occurred, and satellite images of different phases were used to reveal important features of the sources, propagation paths, and velocities of the internal waves in the Bay of Bengal. Finally, we have determined that these waves have a generation period that coincides with the semidiurnal tidal cycle and that their origin is the Nicobar Islands. During their westward propagation in the Bay of Bengal, the internal waves collide and merge with each other, and their propagation velocity is 2.66 m/s. The merged internal wave packets continue to propagate westward, and the propagation velocity increases to a maximum of 3.23 m/s in the open sea, while the wavelength of the wave packets exceeds 220 km. The consistency with the results of internal wave studies in the Andaman and the South China seas illustrates the reliability of this study’s findings.