### ASA 124th Meeting New Orleans 1992 October

## 3aAO4. Stochastic scattering model predictions for reverberation from the
near-surface oceanic bubble layer.

**Kenneth E. Gilbert
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*Appl. Res. Lab. and the Graduate Prog. in Acoust., Penn State Univ., P.O.
Box 30, State College, PA 16804
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A stochastic bubble-layer scattering model has recently been developed
that uses as input the horizontal wave-number spectrum of the sound-speed
fluctuations in the bubble layer [K. E. Gilbert and L. Wang, J. Acoust. Soc.
Am. 90, 2300 (A) (1991)]. The wave-number spectrum is of the form P(K)=AK[sup
-(beta)], where (beta)(approximately equal to)4 is a nearly universal constant
that has been inferred from 11 different deep-ocean reverberation experiments.
To determine the constant A, one needs to know the rms sound-speed fluctuation
in the bubble layer and the horizontal scale of the largest inhomogeneities in
the layer (``outer scale''). In the past year, oceanographic experiments have
directly measured these parameters so that predictions with the stochastic
scattering model can now be more reliably made. In this paper, the scattering
model is briefly reviewed and predictions for backscatter from the bubble layer
using measured oceanographic parameters as input are presented. It is shown
that with oceanographically constrained parameters (i.e., no ``adjustable''
parameters) the stochastic scattering model gives a good account of the
observed backscatter, as a function of both frequency and angle. [Work
supported by ONR.]