Sediment characterization from normal incidence bottom loss at the GLISTEN sea test

The GLider Sensors and payloads for Tactical characterization of the ENvironment (GLISTEN) sea test was conducted off the west coast of Italy in August of 2015. Led by the Centre for Maritime Research and Experimentation (CMRE), the effort included seven other international organizations including the Applied Research Laboratories from The University of Texas at Austin (ARL:UT). The mission of the sea test was to improve and understand long-range acoustic methods of environmental characterization in shallow waters. As part of the test, a team from ARL:UT deployed a remotely operated vehicle (ROV) which collected normal incidence bottom loss data from 6 to 20 kHz along with video and laser line profiling data. These data were taken along the propagation paths of the CMRE low-frequency transmission loss experiment. In this presentation, results will be shown from the bottom loss measurements for a variety of sediments that included both layering and entrained gas pockets. The acoustic data will be compared with models that include such frequency dependent effects as interface roughness and volume scattering. [Work supported by ONR, Ocean Acoustics.]