ASA 125th Meeting Ottawa 1993 May

4pUW11. An empirical model for acoustic backscatter from trapped gas bubbles in sediment.

Frank A. Boyle

Nicholas P. Chotiros

Appl. Res. Labs., Univ. of Texas at Austin, Austin, TX 78713-8029

Recent experimental backscatter data suggest a volume scattering mechanism involving resonant trapped gas bubbles [N. P. Chotiros and F. A. Boyle, J. Acoust. Soc. Am. 89, 1852(A) (1991)]. A preliminary model for shallow grazing angle high-frequency acoustic backscatter from sediment is developed. The model begins with an estimation of grain and pore size distributions based on analyses of existing measurements taken at sea. The bubble size distribution is assumed to follow the pore size distribution. This bubble size distribution is then combined with an existing model for resonant backscatter from bubbles [Clay and Medwin, Acoustical Oceanography: Principles and Applications] to arrive at a model for backscatter from sediments. The model is then compared with existing experimental data.