Spatial correlation of surface generated noise in a stratified ocean

Abstract

A model is developed for the calculation of the spatial properties of the noise field produced in a stratified ocean by the action of wind at the surface. The random noise sources are represented by correlated monopoles distribute d over an infinite plane located an arbitrary depth below the surface. Wave-theoretical methods are applied to derive expressions for the intensity and spatial correlation of the noise field. A normal-mode representation of the noise field is used to reduce these expressions to forms which allow physical interpretation and are suitable for numerical computation. Examples are given of intensity profiles and spatial correlation in the vertical for three generic sound-speed profiles. The results show that the sound-speed profile and the presence of the bottom can be important in determining the spatial properties of the noise field. An example is given of a calculation of the horizontal spatial correlation using the fast field program (FFP).

Synthetic array processing of ocean ambient noise for higher resolution seabed bottom loss estimation

“…6 OASN is part of the OASES acoustic propagation package that numerically implements a full wave solution producing a CSDM for surface noise in a horizontally stratified media using a spectral integration technique. 7 Although the coherence function could be generated using Eq. (3), OASN is used because none of the simplifications made in the preceding derivations are assumed, and this methodology has been used in previous ocean noise and propagation studies.…”

Design of Robust Adaptive Array Processors for Non-Stationary Ocean Environments

“…Although noise measurements were not the primary focus of SPICE04, the experiment provided a large data set of measurements in the band below 200 Hz made with a 40-element vertical line array (VLA). The basic idea is that ambient noise can be represented as a sum of uncorrelated acoustic modes, which is a reasonable assumption for distant sources, e.g., see the work of Kuperman and Ingenito on noise modeling [19]. In this case the eigenvectors of the noise covariance matrix for a vertical line array should correspond to the sampled modeshapes.…”

Design and testing of an acoustic ultra-short baseline navigation system

“…The most important assumption is that the noise present on different sensors will be uncmTelated, additive white Gaussian noise. Ambient ocean noise will of course be generally con·elated spatially and temporally [Kuperman, 1980], but the assumption holds more true for electronics noise [Horowitz and Hill, 1980], which is a larger contributor to the overall noise in the system.…”