Passive tomography of shallow water based on the phase of the cross-correlation function of noise

The possibilities and limitations of using information about the phase of the cross-correlation function of noise signals recorded in spatially separated points of the water area for the purposes of passive tomography of the shallow sea are discussed. In the framework of numerical simulation, the presence of characteristic features of the phase of the Green function near the critical frequencies of hydroacoustic modes is demonstrated. It is revealed that at these frequencies the derivative of the phase has a discontinuity, which can be used as a criterion for estimating the critical frequencies of the waveguide modes. A scheme for reconstructing waveguide characteristics from data in the form of a phase of the mutual correlation function of the noise field and critical frequencies of sonar modes is proposed and implemented numerically. It is shown that taking into account the values of critical frequencies as additional information in the inverse problem solving improves the accuracy of the reconstruction of the waveguide parameters and the noise immunity of the proposed algorithm.