Tomographic Reconstruction of Shallow Water Bubble Fields
Abstract
In the winter of 1997, a shallow water experiment was conducted near the Scripps Pier in La Jolla, California, USA. The goal was to determine the dynamics, distribution and acoustic effects of bubbles just offshore from active surf. A major component of the experiment was the "Delta Frame," an apparatus that supported two acoustic sources and eight receivers. Acoustic intensity was measured at frequencies between 39 and 244 kHz over the resulting 16 horizontal ray paths. Paths ranged in length from 2.5 to 8.6 m. In the present paper, a tomography algorithm is developed and implemented using Delta Frame data. Measurements are combined to produce quantitative cross-sectional images of the attenuation associated with the bubble cloud. Numerical simulations predict that the frame can resolve details of the field down to about 2 m. Images constructed at different acoustic frequencies are scaled and compared. A five-minute sequence of images is studied in detail. Swell waves are shown to cause rapid fluctuations in the images due to the vertical structure of the bubble cloud. At a wave trough, the bubble cloud dips into the horizontal plane probed by the Delta Frame and the attenuation increases.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1999
- Accession Number
- ADA376801
Entities
People
- Daniel Rouseff
- Frank S. Henyey
- Jerald R. Caruthers
- Stephen J. Stanic
Organizations
- University of Washington