ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

5aUW5. Acoustical ray-tracing insonification software modeling of reverberation at selected sites near the Mid-Atlantic Ridge.

Vincent H. Lupien

Joseph E. Bondaryk

Arthur B. Baggeroer

Dept. of Ocean Eng., Rm. 5-435, MIT, 77 Massachusetts Ave., Cambridge, MA 02139

The software package ARTIST is used to model reverberation in a series of pings at selected sites in both monostatic and bistatic configurations. ARTIST is a ray-tracing-based program incorporating array positions and orientations, sound-speed profiles, bathymetry, and beam patterns. Simulated beam-time data are generated by integrating the energy at the seafloor from both arrays, incorporating all sidelobe effects. It is shown that prominent features in the beamformed data match excellently with direct and surface-reflected paths to the seafloor and that these features are dominated by shadowing effects and average grazing angles. The received data show appreciable returns in regions where no direct or surface-reflected paths exist. It is postulated that these returns are part of an underlying, slowly varying reverberation envelope which changes little from ping to ping and is present in bistatic cases as well. Possible physical mechanisms leading to this behavior are presented. The scattering strength of selected seafloor features is presented along with its dependence on grazing and bistatic angles.