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

4pUW10. The influence of sediment scattering and variability on acoustic intensity including data comparisons.

Keith J. Howell

Melvin J. Jacobson

William L. Siegmann

Rensselaer Polytech. Inst., Troy, NY 12180-3590

William M. Carey

Adv. Res. Projects Agency, Arlington, VA 22203-1714

Previous work [Howell et al., 2928 (1994)] has shown that statistics of multimodal intensity could be matched using a three-layer isospeed model that included effects of scattering. To more accurately estimate scattering effects on intensity over a broad frequency range, additional bottom information must be included. In this paper, an analytic treatment of a shallow channel consisting of n isospeed layers is developed for a wide-angle PE propagation model. A scattering layer is introduced at a horizontal water-bottom interface to model effects of attenuation due to interface and sediment scattering. The local mean of intensity is determined and its sensitivity to parameters such as the number of layers, frequency, scattering layer thickness, and correlation length of inhomogeneities is investigated. The standard deviation of intensity is also examined. Comparisons are made between intensity statistics for the multilayer models and depth-dependent profile models consistent with data from a New Jersey Shelf experiment. Additional emphasis is directed toward the number of isospeed layers needed to match experimental intensity over a range of frequencies. [Work supported by ONR.]