Through-the-sensor geoacoustic inversion along a towed horizontal line array: results from real data set in the Mediterranean sea

Abstract

The assessment of active sonar performances in shallow water strongly depends on the environmental conditions. Of most importance, bottom properties are known to strongly affect the forward acoustic propagation and reverberation fields. It is thus essential that reliable geoacoustic models of the seabed be available in a given area so that sonar performances can be estimated with a reasonable level of confidence. In the past decade, several dedicated geoacoustic inversion methodologies have been proposed. Based on experimental set-up's that 'probe' the environment in a similar manner to the one of sonar systems (in terms of used devices and geometries), they aim at assessing a set of seabed parameters that allows to replicate the impact of the true seabed on the acoustical field emitted by a sonar. This paper focuses on the so-called through-the-sensor (TTS) geoacoustic inversion approach that is based on the inversion of acoustical data along a towed horizontal array with matched-field processing techniques. Obviously oriented toward an integration onboard operational low frequency active sonar chains, proofs of the relevantness of that concept have already been shown in the past. Moreover, it has also been demonstrated that such an approach is promising for handling the challenging case of range dependent environment. Here, TTS inversion results with acoustical signals that span the same frequency band of present operational LFAS (800-1800 Hz) are presented. The methodology is applied along a known site Southward the Sicily Island (Malta Plateau) with experimental data.