Acoustic Wave Scattering from a Random Ocean Bottom
WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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This thesis investigates low frequency acoustic wave scattering from the ocean bottom. The first part models the ocean bottom as a fluid medium where sound speed and density are constants except a layer in which the density is still a constant, but the sound speed is composed of a large constant and superimposed with a small random component. In the second part, a integro-differential equation method is used to calculate the scattering from the random layer. Emphasis is put on the study of the spatial correlation of the scattered field. The third part concerns the influence of the bottom roughness. A small roughness is added to the waterbottom interface and perturbation method is used to calculate the scattering from the roughness. Under the assumption that the roughness and volume inhomogeneity are uncorrelated, comparisons are made on the scattering strengths between roughness scattering and volume scattering, and the spatial correlation of the total scattered field is evaluated. In the fourth part, the classical definition of the bottom scattering cross section is questioned, and a new set of parameters, the Scattering Correlation Coefficient, is introduced, which does not have the ambiguities associated with the conventional notion of the scattering cross section.
- Physical and Dynamic Oceanography