Modeling of subcritical penetration into sediments due to interface roughness

Recent experimental results reveal acoustic penetration into sandy sediment s at grazing angles below the critical angle. A mechanism for this subcriti cal penetration is described based on scattering at a rough water-sediment interface. Using perturbation theory, a numerically tractable three-dimensi onal model is used for simulating experiments. The rough interface scatteri ng has been treated using formally averaged methods as well as with single rough surface realizations. Data-model comparisons show that scattering by interface roughness is a viable hypothesis for the observed subcritical pen etration. (C) 2000 Acoustical Society of America. [S0001-4966(00)02301-8].