The importance of breaking internal tides for ocean mixing is well established, but the processes that determine when and where this mixing occurs remain uncertain. This talk discusses tidally driven ocean mixing near the coast, where the continental shelf's steep bathymetry break supports the generation and propagation of coastal trapped waves.
These waves provide an energy pathway linking astronomical forcing to turbulent dissipation and mixing at the ocean's boundaries. Unlike open ocean internal tides, coastal modes cannot be isolated by a barotropic-baroclinic decomposition, and in general coastal modes are not orthogonal. We examine coastal internal tide energy pathways, discussing the interpretations of barotropic-baroclinic conversion and baroclinic flux over the steep topography of the shelf break, and showing specific examples of tidal energy pathways at a range of idealized and realistic coastal topographies. We show that in the presence of along-shelf topographic variability, energy from the gravest Kelvin mode is readily scattered into higher modes with significant along-shelf baroclinic energy flux, though in general this is a notable underestimate of the total wave mode flux.