Acoustic Seabed Classification in Martel Inlet, Antarctica Peninsula Using Multibeam Backscatter Data

Abstract

The acoustic signal of a multibeam echo-sounder is mainly used to extract depth values from its travel time. However, the intensity of that signal with a proper processing can be analyzed as a bottom response, known as backscatter. This information has been used in inversion models to characterize seabed in terms of grain size and roughness. The model used in this paper is based on an angular analysis of the backscatter response, taking into account the sound-seabed relationship, which includes the transmitted and received sound level, acoustic beam patterns and acoustic attenuation in the water column. The aim of this analysis is to represent as accurately as possible the local glaciomarine environment dynamics of the Martel Inlet, Admiralty Bay, South Shetland Island, Antarctica. The multibeam bathymetry and backscatter data were processed and the acoustic classification model was generated in Geocoder 4.1. The generated grain size map was compared to a core sample in the area and to geological maps from previous work. As a result, the final model fit previous regional model, although it was not a good methodology for areas that contain coarse grains. This creates a discussion on the reliability of the method in a geological complex environment as a glaciomarine.