Estimation of the spatial (vertical and horizontal) arrival structure of the undersea ambient noise from towed line array data

Abstract

Towed horizontal line arrays have been used very successfully in the past to acquire data to estimate the horizontal directionality of the ambient noise. Those estimates are commonly called noise roses. A more comprehensive algorithm which estimates the horizontal and vertical arrival structure of the ambient noise from towed line array data has been developed at NRL. The algorithm has been exercised with both simulated and measured data, and the results have been compared to noise roses that have been obtained from the same beam noise data using previous algorithms. The agreement has been good. In addition, the increased dimensionality of the new results has permitted the identification and quantification of spatial ‘‘holes’’ in the noise field that could be exploited by multidimensional arrays to achieve gains well in excess of that which one might expect from adding the independent gains for vertical and horizontal aperture. The algorithm is presented, and some results are discussed. [Work supported by the Office of Naval Research (ONR) and the ASW Environmental Acoustic Support (AEAS) Project.]