5pAO13. Acoustic and optical measurements of bubbles in the surf zone.

Session: Friday Afternoon, December 6

Time: 5:15

Author: Grant B. Deane
Location: Marine Physical Lab., Scripps Inst. of Oceanogr., La Jolla, CA 92093-0238


Breakers in the surf zone generate numerous bubbles which are injected into densely packed clouds below the wave. These clouds affect the acoustics of the surf zone by radiating, absorbing, and scattering sound. The motivation for the present surf zone study is to develop a method to invert passive acoustic measurements of breaking waves to recover the bubble size distribution. Some of the physical processes relevant to inversion studies in the surf zone, such as the episodic nature of air entrainment and high void fractions beneath the breakers, will be discussed. Simultaneous surface video and acoustic measurements of breaking waves have been collected in the surf zone from Scripps Pier. Photographic images of bubbles in a 7 cm x 5 cm x 2 cm volume directly beneath breaking waves have also been taken. Preliminary results of acoustic and optical measurements of the bubble size distribution beneath breakers in the surf zone will be presented. [Work supported by ONR.]

ASA 132nd meeting - Hawaii, December 1996