Abstract

Velocity and turbulence observations are used to estimate the forward cascade of kinetic energy from the internal tide to dissipation within a steep canyon. The semidiurnal tide is the only significant kinetic energy source within the canyon, simplifying the energetic pathway analysis. Two methods for computing cross-frequency kinetic energy flux are compared to observed dissipation. One method, coarse graining, allows strongly nonlinear dynamics while the other assumes weak nonlinearity. Fluxes from both methods are greater than dissipation estimates from the finescale parameterization which is often used in global climate models. Coarse graining reveals energy flux to dissipation from lower internal wave frequencies. These results support the idea that there may be greater kinetic energy cascade due to wave breaking near topography than accounted for by current parameterizations. Enhanced near boundary mixing and upwelling has implications for the rate and spatial distribution of the upwelling branch of the global overturning circulation.