Optimizing Seabed Classification

Underwater acoustics revolves around the analysis of extremely large data sets. Primarily, we are concerned about the transmission of an acoustical signal across the ocean, which is heavily influenced by the transmission loss caused by the reflection by the surface and bottom of the ocean. The interaction between the sound waves and the seafloor can be modeled. While an acousto-elastic parameterization based on sound speeds, attenuations, and density are often used, a more fundamental model incorporates the fundamental properties of the sediment grains in the porous medium. In this Viscous Grain-Shearing model, five parameters are used to describe the sediment: porosity, grain bulk modulus, grain density, a strain hardening index, and a visco-eleastic time constant. The relative influence of each of these parameters on the modeling of transmission loss as a function of frequency is the focus of this research. This research project used information geometry, specifically a model manifold of the transmission loss for different modeling parameters. . The transmission loss is calculated at 16 depths in the shallow ocean for 2500 parameter combinations. This polydimensional transmission loss data is forms a model manifold. A principal component analysis of the model manifold is performed and the first three principal components are used to qualitatively observ the relative impact of the parameters and regimes where reduced- order models may be obtained. These reduce-order models may be used in the future improve modeling efforts for shallow-water anti-submarine defense.