Geoacoustic inversion using seabed reflection-coefficient data variations across frequency

Seabed reflection-coefficient (RC) data as a function of grazing angle and frequency provide rich information content to estimate seabed sediment layering structure and associated geoacoustic properties. To date, Bayesian inversions of wide-angle, broadband RCs have provided high-resolution geoacoustic profiles and uncertainty estimates using data sets based primarily on the Bragg resonance pattern across closely-spaced angles at a small number of frequencies. This paper considers instead the use of RCs across closely-spaced frequencies (including magnitude variations and fringe patterns), which could potentially provide higher information content on certain geoacoustic properties, such as attenuation and its frequency dependence. To investigate this, inversions are carried out based on RCs as a function of frequency from 1–6 kHz at a small number of grazing angles (multiple angles are required to overcome the ambiguity between layer sound speed and thickness). Inversions are evaluated and compared for specific choices of grazing-angle regime, including low angles, high angles, and near the critical angle. [Work supported by the Office of Naval Research.]