### ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

## 2pUW18. Probabilistic range dependence in a numerical average underwater
acoustic propagation method.

**Roger M. Oba
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*Naval Res. Lab., Stennis Space Center, MS 39529-5004
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A computational method for forward propagation of the Helmholtz equation
has been developed for numerically computing average complex pressure field in
a single pass. It used sound-speed profiles be piecewise probabilistically
independent in finite sized range steps to calculate transmission loss and
phase for the average solutions in the continuous wave case. This required that
the uncertainty is probabilistically modeled within range intervals as
ensembles of sound speeds which were independent from one range step to the
next. This method can be modified to represent certain cases for which there is
statistical dependence in range. This can be achieved by nonlocal averaging
over several range steps. The inter-relation of range sound speed and
statistical dependence will be considered, and results from numerical
experiment will be shown. Similar calculations allow the calculation of growth
of standard deviation over range. This modification can also be considered in
the limit of small intervals of uncertainty. [Work supported by Naval Research
Laboratory and the Office of Naval Research.]