Roughness measurement by laser profiler and acoustic scattering strength of a sandy bottom

Abstract

The roughness of a sandy seabed off Panama City, FL, was measured with a laser profiler. This was the site of the target and reverberation experiment of 2013 (TREX13) in which propagation loss and reverberation strength were measured. The area may be characterized as having small scale roughness due to bioturbation overlaying larger sand ripples due to current activity. The area was largely composed of sand with shell hash crossed by ribbons of softer sediment at regular intervals. The roughness measurements were concentrated in the areas where the ribbons intersected the designated sound propagation track. Laser lines projected on the sand were imaged by a high-definition video recorder. The video images were processed to yield bottom profiles in three dimensions. Finally, the roughness data are used to estimate acoustic bottom scattering strength. [Work supported by the Office of Naval Research, Ocean Acoustics Program.]