ASA 126th Meeting Denver 1993 October 4-8

2pUW7. Parabolic equation average propagation in the presence of rapid range variation in a sediment layer.

Roger M. Oba

Acoust. Simulation, Code 7181, Naval Res. Lab., Stennis Space Center, MS 39529-5004

The routine for computing the average solution to the generalized parabolic equation [R. M. Oba, J. Acoust. Soc. Am. 90, 2300(A) (1991)] in the water works for propagation with sediments modeled by fluid layers. It can be used in a ``marching algorithm'' from one range step to another, especially if they are statistically independent. Because the algorithm relies upon analytic forms of matrices for horizontal propagation of vertical modes, a natural limit exists when (a) the sediment variation is rapid compared with wavelength and depth, (b) the sediment variation is statistically independent in each range step, and (c) the probability distribution over the velocity profile ensemble in each range step is identical. Its application to the case where the probability distribution can be parametrized by one variable is demonstrated. This approach has advantages over averages of multiple runs of deterministic models over realizations of sediment velocities. Features of the average solution transmission loss and phase change, preserved by this algorithm, will be discussed. [Work supported by ONR/NRL-SSC and ONR Young Navy Scientist Program.]