Intensity calculations in a random medium with channel velocity profile using coherence theory

Abstract

We use a three scale expansion to calculate the intensity distribution of acoustic radiation propagating in a sound channel in the presence of random inhomogeneities. We develop equations which show how the coherence function varies along the characteristic rays (identical to the rays of geometrical acoustics in the parabolic approximation). Solving these equations we obtain an expression for the vertical intensity distribution resulting from an acoustic beam propagating in a random medium with a sound velocity profile. When the fluctuations of the medium are statistically homogeneous and isotropic, this expression is simplified for two limiting cases: weak scattering and strong scattering. We present an example of high‐frequency scattering in a random medium with a mean cubic profile. We calculate the intensity corrections in the vicinity of a caustic under typical ocean conditions. The results of the corrected intensity distribution are compared with the uncorrected intensity results obtained previously.