Abstract:
During the MPL adaptive beach monitoring experiment conducted in April--June 1995 off Camp Pendleton (north of San Diego, CA), a series of controlled source tows were performed in the nearshore region in 10--20 m of water. Four tones at 95, 145, 195, and 370 Hz were broadcast simultaneously by the source which was 5 m deep and received by two 120-m-long, 64-element, horizontal bottom hydrophone arrays (approximately parallel and perpendicular to the beach) located 3.4 km offshore in 20 m of water. The results from three approaches to carrying out inversions for nearshore seafloor geoacoustic parameters are compared. The first makes use of a simple analytical expression for waveguide effective depth which incorporates the interference wavelength of the first two modes. The second is a wave-number perturbation approach using source tow data from both real and synthetic array apertures. Finally, the third is a full-field inversion for seafloor geoacoustic parameters. [Work supported by ONR, Code 32.]