Scattering measurements of rocky seafloors using a split-beam echosounder

Scattering measurements were made off the coast of Pacific Grove, CA at 200 kHz, in an exposed fractured granite seafloor. Using inertial sensors and a split-beam transducer, data were processed to obtain a range of grazing angles corresponding to scattering strength, and signal processing techniques were used to extract the relevant portion of each ping. The ensonified angular width from a circular aperture is presented. Scattering strength measurements using different assumptions regarding the grazing angle were compared. The empirical Lommel-Seeliger model provided a good fit to measured data with a parameter of −18.4 dB.