The reflection of radiation from randomly irregular surfaces

Surface interactions of radiation propagating in a nonuniform, scattering medium are treated using the strength and diffraction parameters, which currently serve to describe volume scattering in the application of the path-integral formalism. A procedure for tracing the volume diffraction parameter through specular surface reflections is outlined and illustrated. Subsequently, a phase screen model is used to account for scattering by surface irregularities. The statistics of these irregularities take up the role of the statistics of the refractivity fluctuations, and the Rayleigh roughness parameter replaces the strength parameter. The diffraction parameter is defined using the correlation length of the surface irregularities and an appropriate surface phase curvature. The application is illustrated by the computation of the two-point, two-frequency correlation for a surface-to-surface multipath in a linear sound-speed channel.