Matched Field Tomographic Inversion for Geoacoustic Properties

Abstract

Abstract : The geoacoustic properties of the ocean bottom, including sound speed profiles, densities, attenuations and sediment layer depths, have a significant effect on sound propagation in shallow water. The long term goal of this work is to develop a new tomographic inversion method based on matched field processing of broadband data for estimating geoacoustic properties. Matched field tomographic inversion is a relatively new approach (Tolstoy, 94) that is specifically designed for rapid, high resolution estimation of ocean bottom properties. The technique makes use of multiple vertical line arrays, and extends the MF inversion method to 3-D anisotropic environments, i.e. variability in depth, range and cross-range. An experiment to obtain acoustic field data at a multi-array system was successfully carried out using broadband sound sources in the Haro Strait Primer Experiment in June 1996. Initial analysis of the data for estimation of local geoacoustic properties has been reported previously (Chapman et al., 1997). The objectives of the current study are to investigate the performance of the freeze bath method for inversion of the broadband data, and to develop an approach for inverting the range dependent data from the Haro Strait experiment.