Internal Tides Generated on a Corrugated Continental Slope. Part I: Cross-Slope Barotropic Forcing

Abstract

Recent measurements in a region of continental slope characterized by ridges and valleys running up and down the slope reveal interesting high-mode structure in the tidal band velocity signals and enhanced mixing over the corrugations. To deduce the processes responsible for the observed phenomena, numerical simulations of the internal tide generation in this region of topography were performed, focused on the response of the flow to cross-slope barotropic tidal forcing. The flow response is characterized by an internal tide generated at the shelf break that subsequently reflects from the corrugated slope. Above the corrugated slope, a high-mode structure may be created, but only if the Coriolis force is included. It is proposed that interference between the primary internal tide and secondary internal waves forced by the Coriolis-driven along-slope component of primary wave flow field is the cause of the high-mode structure in the simulations. Under suitable conditions of forcing, topography, and stratification, the shear generated by the interference may lead to local mixing. Hence complex topography may be an important contributor to boundary mixing in the ocean.