Coherent and diffusive fields of underwater acoustic ambient noise

In this paper, results of investigations of underwater ambient noise are presented based on statistical analysis of the acoustic pressure and three orthogonal components of particle velocity of a medium P(t), V_x(t), V_y(t), V_z(t). The mathematical analysis used includes cross‐spectral characteristics, simple coherence functions, phase spectra, and an algorithm to split the noise field into anisotropic and isotropic fields. The above approach is applied to study the anisotropic and isotropic fields of ambient noise in the deep open ocean and in a coastal area. A fundamental feature of the anisotropic field that has been revealed is that the direction of the horizontal component of dynamic noise energy flux is similar to the surface roughness propagation direction.