Spectral integral representations of multistatic scattering from sediment volume inhomogeneities

Abstract

A perturbation approximation for multistatic scattering from sediment volume inhomogeneities has been developed using a Fourier–Bessel spectral integral representation of the source and receiver Green’s functions. This approach is particularly efficient for modeling scattering from horizontally isotropic, three-dimensional distributions of scatterers in waveguides with arbitrary horizontal layering, and is accurate for scatterers in fast bottoms near the critical angle and for scatterers in layers with background sound-speed gradients. The theory has been implemented in the oases code and the model has been exercised over broad bandwidths in order to explore the temporal and angular evolution of bistatic scattering for a variety of environmental and experimental scenarios. Examples show that the scattered field received on a bistatic vertical line array shows a distinct evolution in time and angle which can be simply related to the source–receiver geometry and the location of the contributing scatterers at any given time. Similarly, the horizontal angular evolution of bistatic scattering shows a time-angle trajectory which may be easily interpreted using similar geometrical arguments. [Work partially supported by ONR.]