Acoustic Multi-Corer System for Investigation of Seabed Geoacoustic Variability
Abstract
Acoustic propagation in shallow ocean regions is strongly controlled by interaction withthe seabed, and high-resolution geoacoustic data are needed to accurately predict acoustic propagation and scattering in such environments. Furthermore, acoustic variability at the ocean bottom can be introduced by the presence of benthic biological organisms, such as infauna. Depending on the community of organisms present, benthic infauna can re-work the sediment in different ways, altering sediment physical properties, contributing to volume scattering of sound, and affecting seabed pore fluid properties through the production of mucus and other organic matter. These combined effects can manifest as temporal and spatial variability in geoacoustic properties at the seabed surface, including compressional and shear wave propagation, which can have impacts on sonar performance in shallow ocean regions. To quantify the extent to which benthic organisms contribute to seabed spatiotemporal acoustic variability, a new instrument is proposed. The instrument consists of a multi-corer outfitted with two sets of compressional and shear wave probes, which will allow for direct measurement of seabed compressional and shear speed and attenuation along with simultaneous collection of cores for the analysis of infauna community structure and sediment geotechnical properties. As part of the measurement suite, we also propose to conduct high resolution imaging of the seabed surface for the identification of surface features that could indicate the presence of benthic activity. The instrument will yield in situ field data that will be analyzed for relationships between biological abundance and functionality, sediment physical characteristics, and seabed geoacoustic properties. Open questions that the proposed instrument seeks to address are:(i) to what order of magnitude do benthic communities affect seafloor acoustic variability?and (ii) what error is incurred in acoustic propagation predictions using current seabedgeoacoustic models that do not take into account biologically induced variability?
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 17, 2020
- Source ID
- N000142012466
Entities
People
- Kevin M. Lee
Organizations
- Office of Naval Research
- United States Navy
- University of Texas at Austin