Application of Modified Ray Theory to Underwater Sound Propagation.
WOODS HOLE OCEANOGRAPHIC INSTITUTION MASS
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At frequencies of a few hundred Hertz or less, diffraction effects can be significant for sound propagation in the oceans. A modified ray representation for some of these effects has recently been developed. The method applies to propagation through regions of local sound-velocity maximum, and for rays reflected or refracted away from a boundary region with velocity profile monotonically decreasing away from the boundary. In this paper, velocity profiles are considered, varying only with depth, composed of nearly linear and nearly parabolic segments joined with continuous derivative. In this way, modified ray analysis covers a wide class of realistic profiles pertinent to underwater sound propagation. Modified ray analysis is most conveniently formulated as wavelength-dependent ray displacement and leakage phenomena. Ranges for displaced rays at given receiver depth versus ray parameter angle at source are presented for unbounded examples and for profiles bounded by pressure release or rigid surfaces. Leakage coefficients are included for the unbounded examples. Unlike ordinary ray representations, modified rays are not sensitive to small changes in profile. Author