Document Type

Article

Article Version

Publisher's PDF

Publication Date

2017

Abstract

Breaking internal waves are an important contributor to mixing in the stratified ocean interior. We use two-dimensional, nonhydrostatic numerical simulations to examine the breaking of internal waves generated by tidal flow over sinusoidal bottom topography. We explore the sensitivity of the internal wave breaking to the topographic steepness and Coriolis frequency, focusing on the vertical structure of kinetic energy dissipation and the ratio of local dissipation to the barotropic-to-baroclinic energy conversion. When the tidal frequency is twice the local Coriolis frequency, wave breaking above the topography is driven by wave–wave interactions which transfer wave energy from the tidal forcing frequency to the inertial frequency. The greater shear associated with the inertial frequency waves leads to enhanced dissipation in a thick layer above the topography. The topographic steepness strongly modulates this dependence of dissipation on Coriolis frequency; for some steep sinusoidal topographies, most wave energy propagates downward into the topographic troughs, eliminating the possibility for significant breaking above the topographic peaks. Current parameterizations of tidal dissipation in use in global ocean models need to be adapted to include the dependence of the local dissipation on both the Coriolis frequency and the topographic steepness.

Comments

Copyright 2017 the Author(s), published by MDPI under a Creative Commons Attribution License 4.0.

The final publisher PDF has been archived here with permission from the copyright holder.

Publication Title

Fluids

Published Citation

Yi, Y. R., Legg, S., & Nazarian, R. H. (2017). The Impact of Topographic Steepness on Tidal Dissipation at Bumpy Topography. Fluids, 2(4), 55. https://doi.org/10.3390/fluids2040055.

DOI

10.3390/fluids2040055

Peer Reviewed

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