Universal wave approach to ocean acoustic tomography and Cramer-Rao bounds of sound speed field recognition

This work is devoted to the statistical approach to ocean acoustic tomography. Maximum-likelihood (ML) estimate of sound speed field is considered. Deterministic, quasi-deterministic and gaussian signals in the presence of gaussian background noise are examined. A rigorous expression for the functional derivative of the Green function with respect to the sound speed field is applied to find the ML estimate. Fisher information matrices (FIM) giving the Cramer-Rao bounds are obtained for various signal models. The modal, ray and interference tomography methods for global, large scale and small scale inhomogeneities are derived using the statistical approach. FIM of estimate of mode or ray delay are obtained. Some numerical evaluations of potential accuracy of sound-speed field reconstruction in typical propagation conditions are presented