On the Determination of<i>K_v</i>in the Near-Surface Ocean from Acoustic Measurements of Bubbles

Abstract

When wind waves break in deep water, clouds of small bubbles are produced which are diffused downwards by turbulence. We describe here how the vertical diffusion coefficient Kv of the turbulence near the sea surface may be determined from measurements of the bubbles made using a subsurface, upward-directed, high-frequency sonar. The method consists of comparing the observed distributions of scattering cross section with those which can be predicted. Existing observations are used to demonstrate the use of the technique, but are not yet sufficient to allow precise determination of Kv or of its variation with depth or wind speed.