The TRR 181 seminar is held by Ashley Barnes (Australian National University) on July 27, 11 am at Bundesstr. 53 20146 Hamburg, room 22/23.

Topographically generated internal waves as a response to surface wind forcing

Abstract

Two of the most significant sources of internal waves in the ocean are surface winds, and oscillatory flow across topography due to the tides. Bridging these two mechanisms, we propose that wind induced oscillations to sea surface and isopycnal heights are rapidly communicated to the seafloor via hydrostatic pressure. In the presence of appropriate topography, the resulting oscillatory bottom velocity would then generate internal waves in a similar manner to the barotropic tide. We investigated this mechanism in an idealised numerical isopyncal model of a storm passing over a mid ocean ridge, and performed several perturbation experiments altering ocean and wind properties. Bottom generated internal waves were identified in the wake of the storm propagating zonally from the ridge. Estimates of the total wave energy suggest that in the right circumstances these waves could pose a significant source of internal wave energy with up to a 1% conversion rate of the incident wind work.