ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

5aUW16. Diffraction of acoustical waves by spatially localized inhomogeneities in oceanic waveguides.

Sergey M. Gorsky

Vitaly A. Zverev

Alexander I. Khil

Inst. of Appl. Phys. of Russian Academy of Sci., Hydrophys. Dept., 46 Uljanova St., Nizhny Novgorod 603600, Russia

Diffraction of the acoustic fields by spatially localized inhomogeneities in oceanic waveguides has been investigated. The formula for scattering matrix of diffracted waveguide modes has been obtained using a ``short-wave'' approximation. The spatial-frequency diffraction patterns for different locations of inhomogeneities, sources and receivers, and properties both of the spatial-localized inhomogeneities and the waveguides were investigated numerically. The possibilities of diffracted fields measurement in natural waveguides were investigated under the conditions of physical modeling in the ultrasonic frequency region. The significance of physical modeling methods for investigation of diffraction phenomena in ocean was demonstrated. It was shown that the efficiency of diffracted field observations can be increased using results of calculation and measurements under model conditions. The spatial-temporal filtration by horizontal and vertical arrays and by matching processing of complex pulse illumination signals were discussed as methods for isolation of diffracted signals against the background of noise of randomly distributed oceanic inhomogeneities. Besides that, a systematic concept of the structure of perturbed signals in waveguides and an analysis of the possibilities of its observations in layered waveguides were developed.