Vertical coherence along a macroray path in an inhomogeneous anisotropic ocean

This report is a major output of a program in spatial properties of low-frequency acoustic fields in the deep ocean. This project was instituted at the Naval Research Laboratory in 1974 to provide a priori estimates of the capabilities and limitations of large arrays which are due to coherence degradations from environmental causes. The research has emphasized stochastic measures of irregularities in the ocean. This approach has been followed to provide probabilistic predictions of the environmental limits to aperture designs. The elements degrading the spatial coherence of an acoustic signal have been dealt with in the following order: volume effects, bottom effects, and surface effects. Specifically, this report provides the background, theoretical basis, algorithm, and operational information for a FORTRAN computer program called COVERT. This program estimates the effect of stochastic volume scattering on the vertical spatial coherence of an acoustic signal along a single path. The propagation path (determined by the mean sound-speed field) is part of the program input and is termed a macroray path. The scattering employed is appropriate for internal waves; i.e., it is characterized by a high degree of anisotropy, is depth dependent, and is described by a fluctuations spectrum that is characteristic of internal waves. The report summarizes the theoretical formulations on which the program is based, the numerical algorithms used, the input data required, and the outputs that are calculated.