Abstract:
In previous work a high-frequency model for sound scattering by an irregular elastic seabed with volume inhomogeneities and rough water-seabed interface was examined [A. N. Ivakin and D. R. Jackson, J. Acoust. Soc. Am. 98, 2989(A) (1995)]. Scattering from fluid layered sediments with different kinds of irregularities was also considered earlier [A. N. Ivakin, J. Acoust. Soc. Am. 95, 2884(A) (1994)]. But, at many sites, the seabed is of a composite-type consisting of an irregular fluid sediment layer or layers covering an elastic basement. In this case, a fluid scattering model is adequate only for sufficient high frequencies such that absorption renders the influence of the elastic basement negligible. At lower frequencies, sound penetration of the sediment increases, and the effects of scattering from the basement as well as additional channels of scattering from within the sediment due to reflection from the basement become important. These effects are considered and their sensitivity to different model parameters is analyzed. Frequency-angular dependencies of scattering strength are calculated for different types of seabed, and possible applications of predicted interference patterns to remote sensing of the seabed are discussed. [Work supported by ONR.]