Scattering of sound from a point source by a rough surface progressing over an isovelocity ocean

A perturbation procedure is applied, through the second order of approximation, to the three-dimensional problem of scattering of sound from a point source by a rough surface progressing in the wind direction over an isovelocity ocean. The results satisfy conservation of energy, in a ray-theoretic sense, and are uniformly valid throughout the field. At points in the region of surface-image interference (Lloyd’s-mirror region), the signal is shown to be strongly modulated. Results are presented which depict the power in the carrier and signal sidebands. The latter are not, in general, symmetric in amplitude about the carrier. However, it is demonstrated analytically that, on two specific planes in the field, the signal power spectrum is symmetric about the carrier. Subject Classification: 30.40, 30.20, 30.25.