## 4pUW2. A composite model for rough bottom scattering.

### Session: Thursday Afternoon, December 5

### Time: 2:01

**Author: Yevgeniy Y. Dorfman**

**Location: Dept. of Ocean Eng., MIT, Cambridge, MA 02139**

**Author: Ira Dyer**

**Location: Dept. of Ocean Eng., MIT, Cambridge, MA 02139**

**Abstract:**

To be valid and accurate, any model for mid-frequency bistatic scattering
must account for the different scales of roughness found on the bottom. A
composite scattering model was first introduced by Kuryanov. An extension for
this model, similar to the one by Kuryanov, was applied to data acquired during
the 1993 ARSRP cruise. In this model, the scattering surface is represented by a
random surface composed of facets. Each facet is parametrized by a mean slope to
account for large scale roughness and a perturbation to account for small scale
roughness. First, partial coherence of the field over the facet surface is used
to determine the contribution of each individual facet. Then, the scattered
field is calculated via incoherent addition of the contributions from all
facets. The choice of a Gaussian distribution for the mean slope of the facets
results in a good match between the large scale roughness spectrum and the
empirical power law. A simplified model for scattering from the individual
facets assumes that all scatter is directed into the specular direction. This
allows a completely analytical solution and is in reasonable agreement with
experimental data. [Work supported by ONR.]

ASA 132nd meeting - Hawaii, December 1996