SPATIAL DISTRIBUTION AND DIRECTIONALITY OF ACOUSTIC SCATTERING IN ROCKY ENVIRONMENTS

Abstract

The interaction of sound, or an acoustic signal, with the seafloor is an active area of research due to its importance for naval applications in undersea warfare, mine warfare, and special operations, and for remote sensing of seafloor properties for geological and biological research. Seafloor roughness greatly affects acoustic scattering. However, little is known about how much extremely rough seafloors, such as rocky environments, affect the acoustic scattering. Rocky seafloor environments are thought to have extreme spatial variability and increased acoustic scattering compared to sand and mud seafloors. This research analyzed the spatial distribution and directionality of acoustic scattering in rocky environments to determine stationarity and isotropy. Remote sensing software often uses limited historical acoustic data to best fit the scattering parameters in a given environment. The two most common empirical models in remote sensing applications are the Lambert model and the Lommel-Seeliger model. The Lommel-Seeliger (L-S) model proved to be a better fit to this data. The single parameter of the L-S model was used as the proxy to determine whether the scattering strength was stationary or isotropic. The measurements indicated that there was spatial variability and thus non-stationarity to the scattering behavior in both the alongshore and cross-shore directions. Scattering strength was found to be isotropic based on analysis of the survey data as a function of heading.