Note on the redistribution and dissipation of tidal energy over mid-ocean ridges

Abstract

The redistribution and dissipation of internal wave energy arising from the conversion at mid-ocean ridges of the barotropic tide is studied in a set of numerical experiments. A two-dimensional non-hydrostatic model with 100m horizontal and 10-25m vertical resolution is used to represent the detailed processes near an idealised ridge. Conventional internal wave beams at the tidal frequency, ωM2, appear. At the ridge crest, strong tidal energy dissipation occurs that both mixes the fluid and generates strong near-inertial oscillations radiating in near-horizontal beams. Resonant triad interaction between the tidal and inertial motions in turn produces beams at (ωM2 - f), and with high shear, thus effectively mixing fluid at considerable heights above the ridge crest.