Observations of acoustic propagation in the Canada Basin double-duct system from 2016 to 2017 using a 150-km radius tomographic array

John A Colosi; Peter F Worcester; Matthew A Dzieciuch; Bruce D Cornuelle; Heriberto J Vazquez; Christopher W Miller

doi:10.1121/10.0037078

Observations of acoustic propagation in the Canada Basin double-duct system from 2016 to 2017 using a 150-km radius tomographic array

J Acoust Soc Am. 2025 Jul 1;158(1):38-50. doi: 10.1121/10.0037078.

Authors

John A Colosi¹, Peter F Worcester², Matthew A Dzieciuch², Bruce D Cornuelle², Heriberto J Vazquez², Christopher W Miller¹

Affiliations

¹ Department of Oceanography, Naval Postgraduate School, 1 University Circle, Monterey, California 93943, USA.
² Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, USA.

PMID: 40600694
DOI: 10.1121/10.0037078

Abstract

The Arctic Beaufort Sea has a unique double-duct sound-channel capped by seasonal ice cover. A roughly 90-m surface duct (SD) is formed by a river-driven halocline. Below the SD is the approximately 90-m to 250-m depth Beaufort Duct (BD) created by cold Pacific Winter Water sandwiched between warmer Pacific Summer Water and Atlantic Water. A yearlong record (2016-2017) of acoustic propagation measurements in this double-duct system was carried out using a 150-km radius, acoustic tomography array with broadband, 4-hourly transmissions at 175-m depth centered at 250 Hz. Double-duct signal analysis was carried out using a dense-vertical-receiving array spanning the BD. Observations reveal (1) consistent reverse geometric dispersion in the double-duct system with low modes faster than higher modes, (2) distinct first arrival and final cutoff times, and (3) normal dispersion for non-BD/SD modes causing the front to fold back upon itself after the final cutoff. A vertical-wave number spectrogram technique is used to decompose the pulses into an arrival time series for each wave number. Key observables are the first and final arrival travel times, dominant-vertical wave numbers, and signal intensities. Fluctuations are interpreted in terms of the varying stratification, ice cover, and implications for surface heat flux estimation.