Source localization with horizontal arrays in shallow water: Spatial sampling and effective aperture

Abstract

Using vertical line arrays, matched-field processing (MFP) range–depth localization performance in shallow water is often limited by poor sampling of bottom interacting acoustic modes. For off broadside sources, a horizontal array may offer improved mode sampling and localization performance. The relative performance of a horizontal array in mode sampling and localization defines its effective vertical aperture. The MFP performance of several horizontal line array apertures is investigated and compared to a full water column vertical array in a simulated range-independent shallow water environment. It is demonstrated that a horizontal array of sufficient length can equal or exceed the water column vertical array in range–depth localization performance. Expressions are also derived for mode decomposition factors that permit the direct comparison of horizontal and vertical array mode sampling performance. Horizontal array effective aperture can then be computed without the need of extensive MFP test runs. It is shown that the horizontal array effective apertures predicted by these decomposition factors correspond well to actual MFP localization performance for the scenarios considered in this paper. Thus the decomposition factors are a useful tool for array system design for shallow water MFP localization.