Underwater glider localization using broadband source transmissions in the Canada Basin

Abstract

Two Seaglider autonomous underwater vehicles were deployed as mobile receiving platforms in a 2016–2017 tomography experiment in the Canada Basin. The introduction of gliders into a tomography experiment has the advantage of adding acoustic data receptions at many depths and ranges relative to moored acoustic sources. The challenge in interpreting these data is the lack of statistics at any given location and the uncertainty in the glider position during a dive, the latter resulting in a fundamental ambiguity between the position and sound speed. The acoustic arrival matching localization technique, performed in post-processing, has been employed to position the instruments while underwater using transmissions from moored acoustic sources. This technique capitalizes on the broadband nature of the tomography sources and estimates latitude and longitude while relying upon the vehicle’s pressure sensor for depth. Acoustic ranging was also performed onboard the gliders during the deployment, and estimated ranges from the moored sources were transmitted via Iridium satellite link every few hours when the glider surfaced. Positions resulting from acoustic arrival matching localization will be compared with results based on semi-real time acoustic ranging. Results will be discussed in the context of reviewing the state of the art in underwater glider localization.