Variability of observed reverberation and estimated sea-floor scattering strength

Abstract

Sea-floor acoustic scattering strength measurements are useful for understanding the observed reverberation in active sonar systems and for estimating sea-floor bottom properties. Observed reverberation and resulting measured scattering strength frequently show a high degree of spatial and temporal variability. This variability may be observed on short, sample-to-sample, times scales from a single time series, or it may manifest itself as longer term variability of measurements made at a single location or over a survey area. Causal mechanisms for this variability include a dynamic fluctuating ocean media, multipath, complex bathymetry and the use of non-stationary sensors for making these measurements. The results presented in this paper leverage previous work by the Sonar Acoustic Boundary Loss Estimation (SABLE) project. Several examples of how this approach can be used to investigate variability in derived Lambert coefficients and scatter strengths are presented for a dataset constructed from sonar beam data obtained over a limited geographic area. These examples are illustrative of approaches that can potentially be developed as a means of quality control in processing of large datasets from non-research sonar systems.