Abstract:
Internal solitary waves (ISWs) with large amplitudes frequently occur in the Andaman Sea and have important impacts on marine ecology and maritime activities. In this work, the generation and propagation of the ISWs in the southern Andaman Sea are studied with the non-hydrostatic MIT general circulation model (MITgcm). Remote sensing images are used to validate the numerical simulations. First, we investigate the source and propagation speed of the ISWs and find that the ISWs are mainly generated in the following four locations in the Andaman Sea: the Great Channel, the channel between the Nicobar Islands, the shallow water channel at the northern continental slope of the Sumatra Island, and the ridge near the continental slope of northeastern Sumatra Island. These locations are consistent with those observed with remote sensing images. The generation of ISWs is subject to the baroclinic tide regime. Second, we designed sensitivity experiments to investigate the impacts of 2D model effect, strength of background tidal current and structure of topography on the generation and propagation of the ISWs. The simulations show that the propagation speed of the ISWs is between 2.3 and 2.6 m/s, and the maximum amplitude is up to 70 m. By increasing the intensity of background currents in the numerical model, the number of ISWs in each wave packet increases, wave amplitudes become larger and the time interval between adjacent waves shortens. By modifying the local topography in the numerical model, we find that the double-ridge structure can increase the amplitude and the number of ISWs comparing to a single ridge topography.