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

## 2pUW11. An accurate, efficient rough surface parabolic equation program.

**Allan P. Rosenberg
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Steven F. Magruder

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*Johns Hopkins Univ., Appl. Phys. Lab., 7-334, Laurel, MD 20723-6099)
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The parabolic equation program Fepe has been extended to handle a
rough air--water interface treated as a series of stair steps. Because much
finer vertical spacing may be needed to resolve the interface than to propagate
an acoustic wave accurately in the rest of the domain, an option to use one
vertical spacing near the surface and a coarser one in the rest of the ocean
has been implemented. The necessary Galerkin approximations of derivatives on
an unequally spaced grid have been worked out using the symbolic manipulation
program Mathematica. A test case with a realistic surface is provided to
demonstrate the accuracy of the new program Fepersfc. The code is
efficient enough to allow thousands of runs for realistic sized problems, for
example to simulate the effect of a moving surface. [Work supported by the
office of the Chief of Naval Operations.]