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

Abstract

The MAPEX2000 experiments were conducted by the SACLANT Undersea Research Centre in the Mediterranean Sea in March 2000 to determine the performance of acoustic inversion for seabed properties using a towed, horizontal receiver array. Towed systems are advantageous because they are easily deployed from a ship and the moving platform offers the possibility of estimating spatially variable (range-dependent) seabed properties. Previous research has successfully applied matched field processing (MFP) geoacoustic inversion techniques to measured acoustic data, however, in nearly all cases the inverted data were collected on moored, vertical receiver arrays. In the MAPEX2000 experiments acoustic data were collected on both towed and moored vertical receiver arrays. Results will be presented showing that seabed properties (e.g., seabed sound speed, sediment layer thickness and attenuation constant) can be extracted using MFP inversion of acoustic measurements from a towed array of receivers. These seabed properties agree with those inverted using data received simultaneously on a vertical array. These findings imply that a practical technique can be developed to map range-dependent seabed properties over large areas using a towed acoustic system. An example of such a range-dependent inversion is given for two sites from the MAPEX2000 experiments.