Spatial variation of seabed acoustic bulk properties

Abstract

The seabed is modeled as a poro-elastic medium with a rough interface. The spatial variation of bulk properties, along with the interface roughness, are important contributors to the acoustic scattering strength of the seabed. Their effects are often indistinguishable. While roughness may be measured directly, the variability in the bulk properties is more difficult to obtain. In a recent experiment over a sandy seabed off Panama City, FL, known as the target and reverberation experiment of 2013 (TREX13), the seabed roughness and the normal acoustic reflection loss were simultaneously measured using a laser profiler and a short range acoustic sounder deployed aboard a remotely operated vehicle (ROV). Using the measured roughness statistics, the fluctuations in acoustic reflection loss due to roughness were estimated. Subtracting the roughness contribution from the total measured reflection fluctuations, the component due to bulk property changes was estimated, from which the fluctuation in the bulk properties may be inverted. [Work supported by the Office of Naval Research, Ocean Acoustics Program.]