Low-Frequency Sound Propagation in a Fluctuating Infinite Ocean
STANFORD RESEARCH INST MENLO PARK CA
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An approximation is described permitting a relatively simple analytic expression for various statistical averages of the sound-pressure field far from a source in a weakly fluctuating medium. In the low-frequency regime this approximation will permit valid calculations to larger distances than the conventional eikonal, or geometrical optics on straight paths, or perturbation- theory formulae, provided that kLSup 2Cdelta cSup 43 1, where delta cc and L are the fractional sound-speed fluctuations and correlation length respectively, and 2 pik is the sound wavelength. The source-to-receiver range over which the method is valid is R L1kLSup 2cdelta csup 2. The method is used to estimate mean square fluctuations of the sound pressure and coherence lengths in an isotropic infinite ocean, and it is pointed out that its use in the more realistic situation of cylindrical symmetry is not appreciably more difficult.
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