Physics-based inversion of multibeam sonar data for seafloor characterization

As part of a continuing effort to develop a physics-based seafloor inversion technique, both acoustic and environmental data were collected during the Target and Reverberation Experiment 2013 (TREX13). The data were collected along a 350 m long survey track that sampled several sediment types including sand, silty-sand, and mud. A RESON 7125 multibeam sonar was modified to collect data along the track from 150-450 kHz in 50 kHz intervals. Ground-truth data on seafloor properties were acquired along this track, including measurements of roughness, sound speed, attenuation, and both discrete and continuous volume heterogeneity. A model was used to generate echo intensity time series including scattering by both seafloor roughness and volume heterogeneity. Model-data fits were used to provide estimates of acoustic attenuation, volume scattering strength, and roughness spectral parameters. Volume scattering is treated using an empirical model, while roughness scattering is treated using the small-slope approximation. [Work supported by SERDP.]