Remote Estimates of Physical and Acoustic Sediment Properties in the South China Sea Using Chirp Sonar Data and the Biot Model

Abstract

A chirp sonar acquires sea-bed reflection data in the South China Sea, generates imagery of the sediment layering, and estimates sediment properties along the acoustic propagation paths selected for the Asian Sea International Acoustics Experiment (ASIAEX). Normal incidence reflection data, collected by the chirp sonar, are processed with an inversion technique based on the Biot model. The inputs for the inversion are reflection coefficient and attenuation rolloff measurements extracted from chirp sonar reflection data. The inversion provides the acoustic and physical properties of the sediments for the top layer of the sea bed. Porosity, predicted by the inversion, agrees with directly measured porosity. Estimates of porosity, mean grain size, permeability, fast wave velocity, and attenuation (in decibels/meter) are given for the uppermost sediment layer along each of the acoustic propagation lines.