Model/data comparisons of subcritical grazing angle detection of targets buried under a rippled sand interface

Abstract

Subcritical grazing angle target detection results for a sphere buried in Coastal System Station’s Facility 383 pond are compared to predictions from two different models. Both models use perturbation theory to calculate the transmission across the rough interface due to ripple scattering. One is a simple sonar equation model that uses a first-order expression [Eq. (16), Jackson et al., IEEE J. Ocean. Eng. 27, 346–361 (2002)] to calculate the penetration, taking into account the measured ripple profile and the target strength estimate for the buried sphere. The other model uses the penetrating field to calculate target backscattering via a T-matrix formalism adapted to account for the specified sinusoidal roughness. These models have been combined with a reverberation model to predict detection SNR. The reverberation model uses a power law fit to the sand/water interface roughness spectrum determined from measured roughness profiles. [Work supported by ONR.]