A Method for the Simulation and Removal of Multibeam Echosounder Water Column Data Artifacts

Abstract

Modern multibeam echosounders collect bathymetric soundings, seafloor backscatter intensities, and water column backscatter values. The water column data can be used to identify features or biology above the seafloor with a broad range of applications. A key limitation for the analysis of this data is the presence of intrinsic system artifact patterns due to transducer design and receiver-array sidelobe-induced signal interferences. In this article, a method is described for simulating and removing these artifacts based on a “reference ping,” created using a subset of clear water data, which captures intrinsic artifacts present in the original data set. This reference ping, after adjusting for the range and seafloor amplitude values of each ping, is used to simulate ping-specific artifact patterns (“simulated ping”), which can be removed from the original data for improving target identification within the water column. This method was applied to five different Kongsberg Discovery multibeam echosounder systems covering a range of operational characteristics. Comparison of simulated pings with clear water data acquired by all systems shows greater than 0.9 R² correlation, highlighting the efficacy of the method to reproduce intrinsic system artifacts prevalent in commonly used multibeam echosounders. The root-mean-squared error between simulated pings and original data was used to demonstrate the method's effectiveness in removing artifacts, with values of <0.04 for all systems. Large values were also used to identify potential features of interest within the water column. This method provides a promising foundation for improved water column analysis, either as a stand-alone method or combined with other current processing methods.