The TRR 181 seminar is held by Dr. Johannes Becherer (Hereon) on October 20, 11 am in Bundesstr. 53, room 22/23.

Saturation of the Internal Tide over the Inner Continental Shelf

Abstract

Broadly distributed measurements of velocity, density, and turbulence spanning the inner shelf off central
California indicate that (i) the average shoreward-directed internal tide energy flux F_E decreases to near 0 at the 25-m isobath; (ii) the vertically integrated turbulence dissipation rate is approximately equal to the flux divergence of internal tide energy;(iii) going inshore, F_E  becomes decorrelated with the incoming internal wave energy flux; and (iv) F_E  becomes increasingly correlated with stratification toward shallower water.
We develop a framework for understanding these observations. In this framework, the internal tide saturates as it shoals as a result of amplitude limitation with decreasing water depth H. From this framework evolves estimates of averaged energetics of the internal tide; specifically, energy , energy flux, and energy flux divergence, which can be interpreted as dissipation.
These estimates represent a parameterization of the energy in the internal tide as it saturates over the inner continental shelf. The parameterization depends solely on depth-mean stratification and bathymetry. A summary result is that the cross-shelf depth dependencies of energy, flux, and flux-divergence are analogous to those for shoaling surface gravity waves in the surf zone, suggesting that the inner shelf is the surf zone for the internal tide. A test of our simple parameterization against a range of datasets suggests that it is broadly applicable.