Extraction of modal backscattering matrix from reverberation data in shallow‐water waveguide. Part I. Theory

Extracting the bottom backscattering information from reverberation data in shallow‐water waveguide is an attractive but difficult issue. In previous works, some a priori assumption (for instance, the Lambert’s Law, or the separability of the backscattering matrix) has been made in order to solve this problem. In this paper, new approaches are proposed. The modal backscattering matrix can be extracted directly from reverberation data without any a priori assumption on scattering coefficient. The backscattering information inversion is based on the following three components: (1) mode‐filtering at the receiving vertical array, (2) changing the point source depth to obtain different incident mode excitation, and (3) using mode stripping in the waveguide as an additional mode filter. For lower frequency the linear inversion is presented, and for higher frequency the sequential inversion with angle interval smoothing is proposed. [Work supported by ONR.]