### ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

## 5aUW8. Shallow-water reverberation due to sediment volume inhomogeneities.

**Dajun Tang
**

**
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*Dept. of Appl. Ocean Phys. and Eng., Woods Hole Oceanograph. Inst., Woods
Hole, MA 02543
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*
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This is a model of shallow-water reverberation due to sediment volume
inhomogeneities. The scatterers are three-dimensional sound speed and density
variabilities in the sediment. A first-order perturbation approximation is
adopted assuming the sediment variabilities are small quantities. Within the
applicable range of that approximation, this formalism is exact. It is found
that the strength of the scattered field or reverberation strength can be
expressed as the coupling between the incident and scattered normal modes. The
mode coupling coefficient is found to be the same as the scattering coefficient
sampled at relevant modal angles. In the development of the formulation, no
empirical scattering function is involved. Also found is a dispersion factor
associated with each mode in the mean reverberation curve corresponding to the
spreading of the source pulse for each mode. Numerical examples are given for
typical shallow-water environments.