| Popis: |
A theory employing the Kirchhoff approximation and other physical assumptions has been used to obtain a theoretical expression for bistatic surface scattering strength 10 log s(φi,φs) appropriate for the case of a vertically suspended separated source and receiver. In backscattering only one grazing angle φ is involved, and s(φi,φs) reduces to s(φ,φ′) = g2k42π2l2⋅2P(F)Ω3, where 2P(F) is the ocean wave amplitude spectrum density at frequency F = Ω/2π, Ω2 = 2g k cosφ, and l is unit length. At steeper grazing angles where surface shadowing effects are relatively unimportant, the formula provides a good description of the relation between experimental values of 10 log s(φ,φ) and 2P(F) recently reported by Brown and Saenger [J. Acoust. Soc. Amer. 52, 944 (1972)]. Low‐frequency s(φ,φ) data of other investigators will be discussed in light of this theoretical relation. [This work was supported by the Office of Naval Research.] |
