Numerical Simulation of the Generation and Evolution of Internal Tides and Solitary Waves at Sofala Shelf Break

We investigated the dynamics of internal tides (ITs) around the Sofala shelf in the Mozambique Channel based on a 3-D hydrostatic numerical simulation. Two distinct sources of ITs and their basic propagation properties were identified. The depth-integrated period-averaged baroclinic energy flux indicated IT propagation away from the generation sites, particularly toward the east and the southeast. The convergence and divergence of the baroclinic energy flux were attributable mainly to special bathymetry features. Based on these results, 2-D nonhydrostatic experiments were performed to simulate the generation and propagation of baroclinic tides along the main energy path. The model reproduced the two distinct generation processes of internal solitary waves (ISWs): the disintegration of the interfacial mode 1 IT and the beam-induced local generation in the open ocean. The IT beam emanated from the critical slope region, then moved downward toward the deep ocean, where it reflected at the bottom. It then impinged on the pycnocline and created a strong disturbance, which further evolved into an ISW after propagation of approximately 20 km. The simulation also captured the interlaced properties of the two wave types, 60-80 km from the shelf-break region, similar to the available observations.