Underwater Scattering of Sound
Final rept. 16 Dec 1981-15 Jun 1990
CHICAGO UNIV IL
Pagination or Media Count:
Scattering by distributions of discrete irregularities in the sea volume, and on its surface and bottom, influence propagation phenomena basic to underwater communication and allied programs. To isolate essential aspects, key surface and volume distributions were investigated. This research deals with sea surface, seabottom, and sea volume effects on propagation that can be analyzed in terms of scattering by statistical distributions of discrete irregularities e.g., ridges on a surface, or particles in a medium. The irregularities exist in the sea surface topped by an air or ice cover, the sea volume, and in the seabottom. The gross physical properties for coherent propagation of sound are represented by bulk parameters and surface impedances determined by averaging the field over the ensemble of statistical distributions of the irregularities their shapes, sizes, physical parameters, locations, separations, etc. In general, the first approximation for the coherent field the average wave corresponds to phase and absorptive effects. Fluctuations with respect to average values lead to incoherent scattering, and to the associated attenuation of the coherent wave. In addition to obtaining more complete results for the coherent wave for key statistical problems, simplified forms for the incoherent scattering were also developed.