Trans-dimensional inversion of modal dispersion data collected by an underwater glider

Abstract

Acoustic payload equipped underwater gliders have been proven to have great potential for maritime intelligence, surveillance, and reconnaissance missions, as well as oceanic environment characterization. This paper demonstrates 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 two combustive sound-source signals were emitted at a separation of about two minutes in time. The glider was programmed to follow a sawtooth-like track through the water approximately 8 km from the source. Both source and glider were in an area where water depth is around 72 m. The two transmissions were received by the glider at depths separated by about 15 m. Discrepancies in the modal dispersion structure of the received signals were observed, as expected for different reception depths. Trans-dimensional geoacoustic inversion is applied to the modal-dispersion data to study the consistency of the inversion results for signals received at different depths. The benefit of combining signal receptions at different depths in the inversion to reduce the uncertainties of the geoacoustic estimates is also addressed. [Work supported by ONR.]