ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

2pAO7. Depth-dependent gas fractions in acoustic models of marine sediments.

Frank A. Boyle

Nicholas P. Chotiros

Appl. Res. Labs., Univ. of Texas, P.O. Box 8029, Austin, TX 78713-8029

Models have recently been developed for acoustic scattering from trapped gas bubbles in sandy and silty marine sediments [F. A. Boyle and N. P. Chotiros, 3219 (A) (1994) and F. A. Boyle and N. P. Chotiros, 1766 (A) (1993)]. These preliminary models may be somewhat limited in applicability due to an assumption that the bubbles are distributed homogeneously throughout the half-space below the sediment interface. Observations suggest that actual sediments are horizontally stratified, and that gas fractions have strong depth dependence. The models have therefore been modified to allow specification of a depth-dependent gas fraction. Studies suggest that the backscattering strength is significantly affected, with considerable influence on its grazing angle dependence. [Work supported by Naval Research Laboratory, Stennis Space Center under the MCM Tactical Environmental Data System (MTEDS) project.]