title: Bowhead whale localization using time-difference-of-arrival data from asynchronous recorders.
abstract: This paper estimates bowhead whale locations and uncertainties using nonlinear Bayesian inversion of the time-difference-of-arrival (TDOA) of low-frequency whale calls recorded on onmi-directional asynchronous recorders in the shallow waters of the northeastern Chukchi Sea, Alaska. A Y-shaped cluster of seven autonomous ocean-bottom hydrophones, separated by 0.5-9.2 km, was deployed for several months over which time their clocks drifted out of synchronization. Hundreds of recorded whale calls are manually associated between recorders. The TDOA between hydrophone pairs are calculated from filtered waveform cross correlations and depend on the whale locations, hydrophone locations, relative recorder clock offsets, and effective waveguide sound speed. A nonlinear Bayesian inversion estimates all of these parameters and their uncertainties as well as data error statistics. The problem is highly nonlinear and a linearized inversion did not produce physically realistic results. Whale location uncertainties from nonlinear inversion can be low enough to allow accurate tracking of migrating whales that vocalize repeatedly over several minutes. Estimates of clock drift rates are obtained from inversions of TDOA data over two weeks and agree with corresponding estimates obtained from long-time averaged ambient noise cross correlations. The inversion is suitable for application to large data sets of manually or automatically detected whale calls.
authors.affiliation: School of Earth and Ocean Sciences, University of Victoria, 3800 Finnerty Road, Suite 405A, Victoria, British Columbia V8P 5C2, Canada.
authors.forename: Graham A
authors.initials: GA
authors.lastname: Warner
authors.affiliation: School of Earth and Ocean Sciences, University of Victoria, 3800 Finnerty Road, Suite 405A, Victoria, British Columbia V8P 5C2, Canada.
authors.forename: Stan E
authors.initials: SE
authors.lastname: Dosso
authors.affiliation: JASCO Applied Sciences, 2305-4464 Markham Street, Victoria, British Columbia V8Z 7X8, Canada.
authors.forename: David E
authors.initials: DE
authors.lastname: Hannay
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D000818:Animals; D001499:Bayes Theorem; D004867:Equipment Design; D009038:Motion; D017711:Nonlinear Dynamics; D012815:Signal Processing, Computer-Assisted; D013016:Sound; D013018:Sound Spectrography; D013997:Time Factors; D014159:Transducers; D014828:Vocalization, Animal; D014907:Whales / Q000145:classification / Q000502:physiology*