Range-dependent seabed characterization by inversion of acoustic data from a towed receiver array

Abstract

The MAPEX2000 experiments were conducted in the Mediterranean Sea in March, 2000 to determine seabed properties using a towed acoustic source and receiver array. Towed systems are advantageous because they are easy to deploy from a ship and the moving platform offers the possibility for estimating spatially variable (range-dependent) seabed properties. In this paper, seabed parameters are determined using a matched-field geoacoustic inversion approach with measured, towed array data. Previous research has successfully applied matched-field geoacoustic inversion techniques to measured acoustic data. However, in nearly all cases the inverted data were collected on moored, vertical receiver arrays. Results here show that seabed parameters can also be extracted by inverting acoustic measurements from a towed array of receivers, and these agree with those inverted using data received simultaneously on a vertical array. These findings imply that a practical technique could be developed to map range-dependent seabed parameters over large areas using a towed acoustic system. An example of such a range-dependent inversion is given using measurements from the MAPEX2000 experiments.

Geoacoustic inversion in time domain using ship of opportunity noise recorded on a horizontal towed array

“…1,2 In order to avoid this degradation of resolution, towed horizontal line array ͑HLA͒ inversion schemes have been proposed and implemented. [3][4][5][6] The short distance between a sound source and HLA enables us to simplify the range dependence into local segments of range-independent sectors. 6 The towed HLA system possesses additional advantages of mobility and manageability, which are inherently suitable for a towed sonar system compared to a VLA.…”

Range-dependent geoacoustic inversion of vertical line array data using matched beam processing

“…The towed HLA system has several advantages over a VLA, such as mobility and manageability, and provides simplicity of the inversion modeling based on assuming range independency in local regions between the source and receiver. 4,5 On the contrary, a VLA configuration is relatively stable and capable of receiving sound fields from all directions and can probe large areas around the VLA with a towed source or multiple sources. [6][7][8][9][10][11] Although there is some computational complexity in propagation modeling, VLA configurations are still effective in range-dependent inversion.…”

“…To prevent such degradation in inversion modeling accuracy, research has been conducted on rangedependent geoacoustic inversion. [4][5][6][7][8][9][10][11][12] Towed horizontal line array ͑HLA͒ schemes are one such range-dependent inversion method. The towed HLA system has several advantages over a VLA, such as mobility and manageability, and provides simplicity of the inversion modeling based on assuming range independency in local regions between the source and receiver.…”

“…The MF inversion has been successfully applied to estimate bottom characteristics in various shallow water environments. [1][2][3][4][5][6][7][8][9][10][11][12] Actual shallow water environments usually have range variability in seabed properties as well as in bathymetry or ocean sound speed. However, in conventional geoacoustic inversions using a vertical line array ͑VLA͒ and a single source, the geoacoustic properties have been typically assumed to be range independent.…”

Bayesian geoacoustic inversion of ship noise on a horizontal array

“…Much work on MFI has been performed using high-level acoustic sources and vertical line arrays of sensors. [1][2][3][4][5][6][7] Recent interest has expanded to include applications to data from towed [8][9][10][11] and bottom-moored [12][13][14] horizontal line arrays ͑HLAs͒, and the use of alternative sound sources such as noise from the tow ship received on a towed array, 9,10 or from ships of opportunity received on moored arrays. 15,16,13 The use of ship noise in both cases reduces environmental impact over a controlled source.…”