Ambient noise depth-dependence models and their relation to low-frequency attenuation

Both a deterministic dipole model and the law of conjugate depths are applied to study the depth dependence of the low-frequency ambient noise in the main sound channel and, when used together, a reasonable agreement with experiment is obtained. Scattering or diffusion models for the region below critical depth agree well with experiment. Complete area and line source models for the ambient level are derived. Three approximate predictions of the low-frequency attenuation come from the deep ambient depth dependence, ambient differences with site position, and ambient differences with site and depth, respectively. All three are consistent with conventional measurements and with the scattering diffusion and bottom loss mechanism.