ASA 127th Meeting M.I.T. 1994 June 6-10

3pUW19. Shallow water sediment layer structure and composition effects on range-dependent transmission loss at the AGS site.

K. P. Bongiovanni

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

Mohsen Badiey

Univ. of Delaware, Newark, DE 19716

W. L. Siegmann

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

Effects of geological features in shallow water sediment layers on acoustic propagation are examined using numerical simulations and measured experimental data. Accurate geoacoustic data from the New Jersey Shelf AGS site provide profiles of compressional and shear sound speed, attenuation, and density, and along with detailed bathymetry are used for input to transmission loss and wave-number calculations. In order to examine range-dependent effects of geoacoustic properties and geological structures in this region, frequency domain parabolic equation (PE) models (one of which includes sediment shear) are efficient and accurate for the required simulations. Sensitivities to variations in geometrical sediment structure, including numbers of sediment layers and interfacial depth and range dependences, are considered to investigate influences of sediment characteristics on the acoustic field. Uncertainties in material geoacoustic parameters and sensitivities to required horizontal and vertical resolution of modeled geoacoustic data are also examined. Additional comparisons of PE simulations illustrate the influence of shear effects in this shallow water environment. Preliminary discussion of simulation results and of sediment layering effects on acoustic propagation will be given in connection with experiments. [sup a)]Present address: Office of Naval Research, Ocean Acoustics program Code 324OA, 800 North Quincy St., Arlington, VA 22217-5000.