Estimating uncertainty in subsurface glider position using transmissions from fixed acoustic tomography sources

Four acoustic Seagliders were deployed in the Philippine Sea November 2010 to April 2011 in the vicinity of an acoustic tomography array. The gliders recorded over 2000 broadband transmissions at ranges up to 700 km from moored acoustic sources as they transited between mooring sites. The precision...

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Bibliographic Details
Published in:The Journal of the Acoustical Society of America 2013-10, Vol.134 (4), p.3260-3271
Main Authors: Van Uffelen, Lora J, Nosal, Eva-Marie, Howe, Bruce M, Carter, Glenn S, Worcester, Peter F, Dzieciuch, Matthew A, Heaney, Kevin D, Campbell, Richard L, Cross, Patrick S
Format: Article
Language:English
Subjects:
Acoustics - instrumentation
Equipment Design
Geographic Information Systems
Least-Squares Analysis
Models, Statistical
Motion
Oceanography - instrumentation
Oceanography - methods
Oceans and Seas
Salinity
Seawater
Signal Processing, Computer-Assisted
Sound
Sound Spectrography
Surface Properties
Temperature
Time Factors
Transducers
Uncertainty
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Summary:Four acoustic Seagliders were deployed in the Philippine Sea November 2010 to April 2011 in the vicinity of an acoustic tomography array. The gliders recorded over 2000 broadband transmissions at ranges up to 700 km from moored acoustic sources as they transited between mooring sites. The precision of glider positioning at the time of acoustic reception is important to resolve the fundamental ambiguity between position and sound speed. The Seagliders utilized GPS at the surface and a kinematic model below for positioning. The gliders were typically underwater for about 6.4 h, diving to depths of 1000 m and traveling on average 3.6 km during a dive. Measured acoustic arrival peaks were unambiguously associated with predicted ray arrivals. Statistics of travel-time offsets between received arrivals and acoustic predictions were used to estimate range uncertainty. Range (travel time) uncertainty between the source and the glider position from the kinematic model is estimated to be 639 m (426 ms) rms. Least-squares solutions for glider position estimated from acoustically derived ranges from 5 sources differed by 914 m rms from modeled positions, with estimated uncertainty of 106 m rms in horizontal position. Error analysis included 70 ms rms of uncertainty due to oceanic sound-speed variability.
ISSN:0001-4966
1520-8524
DOI:10.1121/1.4818841