Scattering from a rough sedimental seafloor containing shear and layering

A simple first‐order perturbation approach is presented, which directly determines the acoustic field scattered by a rough seafloor. The theory is based on the Born approximation. The seafloor is allowed to be shear‐supporting or to be layered. Scattering strengths are derived for both monostatic and bistatic scattering, and discussed with respect to their dependence on seafloor parameters and roughness spectrum. Power‐law wave‐number spectra are found to be appropriate for explaining important features of backscatter, which are the magnitude, the frequency, and grazing‐angle dependence. For grazing angles below critical, shear‐wave velocities exceeding some 350 m s⁻¹ significantly modify the scattering strength. With respect to narrow‐band acoustic signals layering of the seafloor may be of importance. Numerical results are presented for the frequency range 10–100 kHz.