Can oceanic flows be heard? Abyssal melodies

Abstract

Fluid flows generate an acoustic noise field. In principle, oceanic flows on varying time and length scales produce a sound field and its detectability is considered here. A fragile lower bound analysis is made of the acoustic signature, using the Lighthill theory, of a simple train of boundary vortices generated by baroclinic tidal flows. Subject to numerous assumptions, the accompanying sound should be detectable within the hum band of seismo-acoustic pressure fields, and more generally, across the entire oceanic spectrum—likely through wave number analyses of spatially coherent acoustic array data.