Extracting sea-bottom information from reverberation data

Abstract

Reverberation measurements contain information about both the scattering and propagation effects. This paper will discuss our efforts to extract bottom loss and bottom scattering from reverberation data, including at-sea results obtained during three recent Rapid Environmental Assessment (REA) trials with the SACLANT Undersea Research Centre. There is often a strong interrelationship between the bottom loss and scattering, and attempts to deal with the uniqueness of the extracted parameters are discussed. Earlier attempts using another simplified, but automated, inverse scheme indicated very good agreement with independently measured bottom loss. In the recent REA trials the initial bottom loss was obtained using some a priori geologic information for the experiment area. Then the bottom parameters were manually adjusted to obtain a good fit to the data from several nearby locations and array headings. The best fits were obtained by first adjusting the bottom loss to fit the rate of decay, and then adjusting the strength of the Lambert coefficient to fit the level.