### ASA 127th Meeting M.I.T. 1994 June 6-10

## 5pUW5. Self-consistent scattering theory for normal mode propagation.

**Brian H. Tracey
**

**
Henrik Schmidt
**

**
**
*Dept. of Ocean Eng., MIT, 77 Massachusetts Ave., Bldg. 5-007, Cambridge,
MA 02139
*

*
*
Rough surface scattering in ocean waveguides causes a loss of signal
coherence and transfers energy between the guided modes of the waveguide. These
effects are important for prediction and signal processing applications, and
have been studied using techniques such as coupled mode theory. As an alternate
approach, a self-consistent perturbational scattering theory developed by
Kuperman and Schmidt [W. A. Kuperman and H. Schmidt, J. Acoust. Soc. Am. 57,
1511--1522 (1989)] is rewritten in terms of a normal mode representation of the
pressure field. This approach is significantly less computationally intensive
than the wave-number integration formulation used previously. The decay of the
coherent field and statistics of the scattered field such as the cross-modal
coherences can be calculated. The approach allows an arbitrary number of layers
separated by rough interfaces and can be extended to elastic media as well.
Numerical results are presented for a realistic shallow-water ocean
environment. [Work supported by ONR.]