Passive Acoustic Glider for Seabed Characterization at the New England Mud Patch
Acoustic payload-equipped underwater gliders are proving to have great potential for maritime intelligence, surveillance, and reconnaissance missions, as well as oceanic environment characterization. This article demonstrates their capabilities for seabed characterization using broadband signals received on a hydrophone-equipped Teledyne Webb Research Slocum glider during the 2017 Seabed Characterization Experiment (SBCEX) conducted on the New England Mud Patch. In the experiment, a source ship maintained a fixed position while combustive sound-source signals were emitted at about 2 min intervals. The glider was programmed to follow a sawtooth-like track through the water column approximately 8 km from the source in an area where the water was ∼72 m deep. Two transmissions were received by the glider at depths separated by about 15 m. Trans-dimensional Bayesian geoacoustic inversion was applied to modal-dispersion data extracted from the received signals via a time-warping technique to study the consistency of the inversion results for signals received at different depths, and the advantages of including signal receptions at different depths in simultaneous inversion. The inferred geoacoustic properties are in good agreement with independent core measurements collected during a geophysical survey, and with other inversion results using data collected by dedicated bottom-moored receivers in the vicinity.