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 100 m horizontal and 10–25 m vertical resolution is used to represent the detailed processes near an idealised ridge. Conventional internal wave beams at the tidal frequency, [superscript ѡ]M[subscript 2], 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 ([superscript ѡ]M[subscript 2] - f) and with high shear, thus effectively mixing fluid at considerable heights above the ridge crest.