Considerations in the modelling of seafloor acoustic backscatter

Basic scattering mechanisms and empirical studies of seafloor backscatter are reviewed. The Rayleigh criterion offers a means of classifying a rough surface. The Rayleigh parameter, a measure of vertical roughness, and the Rayleigh reflection coefficient, a measure of reflection loss between boundaries, are reviewed. The task of modeling the scattering from a surface with two scales of roughness is approached using a combination of two scattering approximations, one valid for small-scale roughness and one valid for large-scale roughness. The small perturbation method is used for small-scale roughness, and the method of tangent plane, or Kirchoff approximation, is used for large-scale roughness