Scattering of an obliquely incident mode-one internal tide off a continental shelf and slope

Low-mode internal tides are ubiquitous in the abyssal ocean, as demonstrated in many in situ and remote sensing observational studies as well as numerical investigations. While various researchers have examined the scattering of these waves at a coastal margin when incidence is normal to the coast, few studies have investigated scattering when the internal tide propagates at an oblique angle toward the coast. Oblique propagation allows for the possibility of the incident internal tide to scatter into ‘leaky’ edge waves that are partially trapped and propagate along the coast. The focus of this numerical study, utilizing the hydrostatic, primitive equation ocean model ROMS, is on the response over the continental shelf and slope to an obliquely incident internal tide and its dependence on incidence angle, stratification, and shelf/slope structure (specifically the width of the shelf). The domain consists of an abyssal ocean with constant depth and a steep shelf (small width relative to an internal tide wavelength) and flat continental shelf that do not vary in the along-coast direction. A body-force is used to force a mode-one internal tide incident on the coast. We find that, upon scattering, much of the energy is reflected offshore. However, some energy remains trapped on the shelf as a leaky edge wave. The amount of energy that remains trapped to the coast is sensitive to the width of the shelf relative to the cross-shore wavelength of the internal tide on the shelf.