The effect of asymmetrical topography on the generation of internal waves

Internal wave generation over steep topography, such as a ridge or sill, is a well observed phenomenon in the ocean. In this study, internal waves in an idealized oceanographic setting are generated by barotropic tidal flow over a two-dimensional ridge, using a nonhydrostatic numerical model. A series of experiments are performed in which internal waves are generated on topography with a steep slope on one side, while the other slope varies in gradient. The impact of bottom topography shape on wave generation is examined. The results show that the response changes greatly depending on the steepness of the varying slope. If the varying slope is subcritical, internal wave energy flux is a minimum, despite the fixed slope being critical. The energy flux increases with increasing slope if the slope is near critical. Further increases in slope gradient produce a maximum in energy flux. The Mascarene Plateau in the western Indian Ocean is examined in this context. The Mascarene Plateau is asymmetrical with a steeper slope on the west side. The slightly larger intensity of internal waves on the west side of the Mascarene plateau agrees with the asymmetrical ridge topography. The surface currents and latitude are found to be of lesser impact on the generation of internal waves than the change in topographical slope in this case. The westward internal wave is slightly more susceptible to changes in surface current than its eastward counterpart for all cases.