| The ambient noise field in shallow water is strongly affected by the presence of the seabed. As a result, the noise contains structure that depends on the seabed characteristics. This structure is measurable in terms of the second order statistical properties of the noise. In this thesis a new procedure is developed to invert for the geoacoustic seabed parameters using the broadband vertical coherence from a single hydrophone pair. The inversion is used to estimate the compressional wave speed ;A full wave theoretic model is developed for the vertical directionality and the vertical coherence of the noise. Using the directionality determined from a multi-element array, the individual seabed properties are manifest as the critical angle, intermediate mode stripping, and high order trapped mode stripping for ;Inversions are performed for the geoacoustic seabed parameters using ambient noise data from four ocean locations. The noise estimates are in good agreement with independent measurements and demonstrate the feasibility of inverting for all three geoacoustic parameters. This passive, two hydrophone measurement provides a simple, inexpensive alternative to more conventional procedures used in estimating the seabed parameters. |
