On the Reflection of Internal Wave Groups from Sloping Topography

Strong interactions, often leading to wave breaking and mixing, are known to occur between a train of internal waves, incident on a plane sloping ocean boundary, and its reflection propagating away from the slope. Intermittent processes of internal-wave generation at the sea surface or ocean floor, however produce packets or groups of internal waves. The size of the volume within which an internal wave group of narrow bandwidth overlaps with its reflection from a plane boundary depends on the finite dimensions of the group. The height above a slope within which interactions can occur is calculated as a function of the direction of approach of the incident group to the plane. Wave groups traveling with positive downslope group velocity components, such as internal tidal rays generated at the shelf break, produce relatively thicker interaction regions than do groups of equal dimensions and frequency approaching a slope from deep water. In some regions, the thickness of layers of enhanced mixing over continental slopes or on the flanks of deep ocean ridges may be determined by the scale of reflecting internal wave groups rather than by, for example, the straining of the ambient wave field by radiating internal tidal waves.