ON BUBBLE CLOUDS PRODUCED BY BREAKING WAVES - AN EVENT ANALYSIS OF OCEAN ACOUSTIC MEASUREMENTS

A field experiment was carried out to measure the time-varying propert ies of bubble clouds as they evolve from ocean breaking waves. The exp eriment was conducted from the floating instrument platform Flip and c onsisted of simultaneous, colocated acoustic measurements of subsurfac e bubbles and video recordings of the sea surface. Details of two brea king wave events are presented. The results of the acoustic measuremen ts of bubble density and their entrainment depth are reported for the time t/T-c greater than or similar to 3, where t is the time from brea king and T-c is a characteristic timescale based on the speed of the b reaking wave crest as estimated from the video recordings. Order of ma gnitude values for the air-void fraction beta, vertical eddy diffusivi ty k(v), and kinetic energy dissipation epsilon associated with breaki ng waves are presented. The wind speed dependence of average acoustic backscattering properties over the course of the experiment is also gi ven.