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Eastern Arctic ambient noise on a drifting vertical array.

https://arctichealth.org/en/permalink/ahliterature286813
Source
J Acoust Soc Am. 2017 Oct;142(4):1997
Publication Type
Article
Date
Oct-2017
Author
Emma Ozanich
Peter Gerstoft
Peter F Worcester
Matthew A Dzieciuch
Aaron Thode
Source
J Acoust Soc Am. 2017 Oct;142(4):1997
Date
Oct-2017
Language
English
Publication Type
Article
Abstract
Ambient noise in the eastern Arctic was studied from April to September 2013 using a 22 element vertical hydrophone array as it drifted from near the North Pole (89° 23'N, 62° 35'W) to north of Fram Strait (83° 45'N, 4° 28'W). The hydrophones recorded for 108?min/day on six days per week with a sampling rate of 1953.125?Hz. After removal of data corrupted by non-acoustic transients, 19 days throughout the transit period were analyzed. Noise contributors identified include broadband and tonal ice noises, bowhead whale calling, seismic airgun surveys, and earthquake T phases. The bowhead whale or whales detected are believed to belong to the endangered Spitsbergen population, and were recorded when the array was as far north as 86° 24'N. Median power spectral estimates and empirical probability density functions along the array transit show a change in the ambient noise levels corresponding to seismic survey airgun occurrence and received level at low frequencies and transient ice noises at high frequencies. Median power for the same periods across the array shows that this change is consistent in depth. The median ambient noise for May 2013 was among the lowest of the sparse reported observations in the eastern Arctic but comparable to the more numerous observations of western Arctic noise levels.
PubMed ID
29092535 View in PubMed
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Observations of sound-speed fluctuations in the Beaufort Sea from summer 2016 to summer 2017.

https://arctichealth.org/en/permalink/ahliterature311087
Source
J Acoust Soc Am. 2021 Mar; 149(3):1536
Publication Type
Journal Article
Date
Mar-2021
Author
Murat Kucukosmanoglu
John A Colosi
Peter F Worcester
Matthew A Dzieciuch
Daniel J Torres
Author Affiliation
Department of Ocean Sciences, University of California, Santa Cruz, California 95060, USA.
Source
J Acoust Soc Am. 2021 Mar; 149(3):1536
Date
Mar-2021
Language
English
Publication Type
Journal Article
Abstract
Due to seasonal ice cover, acoustics can provide a unique means for Arctic undersea communication, navigation, and remote sensing. This study seeks to quantify the annual cycle of the thermohaline structure in the Beaufort Sea and characterize acoustically relevant oceanographic processes such as eddies, internal waves, near-inertial waves (NIWs), and spice. The observations are from a seven-mooring, 150-km radius acoustic transceiver array equipped with oceanographic sensors that collected data in the Beaufort Sea from 2016 to 2017. Depth and time variations of the sound speed are analyzed using isopycnal displacements, allowing a separation of baroclinic processes and spice. Compared to lower latitudes, the overall sound speed variability is small with a maximum root mean square of 0.6?m/s. The largest source of variability is spice, most significant in the upper 100?m, followed by eddies and internal waves. The displacement spectrum in the internal wave band is time dependent and different from the Garret-Munk (GM) spectrum. The internal wave energy varied with time averaging 5% of the GM spectrum. The spice sound-speed frequency spectrum has a form very different from the displacement spectrum, a result not seen at lower latitudes. Because sound speed variations are weak, observations of episodic energetic NIWs with horizontal currents up to 20?cm/s have potential acoustical consequences.
PubMed ID
33765810 View in PubMed
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Temporal and spatial dependence of a yearlong record of sound propagation from the Canada Basin to the Chukchi Shelf.

https://arctichealth.org/en/permalink/ahliterature304683
Source
J Acoust Soc Am. 2020 09; 148(3):1663
Publication Type
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Date
09-2020
Author
Megan S Ballard
Mohsen Badiey
Jason D Sagers
John A Colosi
Altan Turgut
Sean Pecknold
Ying-Tsong Lin
Andrey Proshutinsky
Richard Krishfield
Peter F Worcester
Matthew A Dzieciuch
Author Affiliation
Applied Research Laboratories, The University of Texas at Austin, Austin, Texas 78713, USA.
Source
J Acoust Soc Am. 2020 09; 148(3):1663
Date
09-2020
Language
English
Publication Type
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Abstract
The Pacific Arctic Region has experienced decadal changes in atmospheric conditions, seasonal sea-ice coverage, and thermohaline structure that have consequences for underwater sound propagation. To better understand Arctic acoustics, a set of experiments known as the deep-water Canada Basin acoustic propagation experiment and the shallow-water Canada Basin acoustic propagation experiment was conducted in the Canada Basin and on the Chukchi Shelf from summer 2016 to summer 2017. During the experiments, low-frequency signals from five tomographic sources located in the deep basin were recorded by an array of hydrophones located on the shelf. Over the course of the yearlong experiment, the surface conditions transitioned from completely open water to fully ice-covered. The propagation conditions in the deep basin were dominated by a subsurface duct; however, over the slope and shelf, the duct was seen to significantly weaken during the winter and spring. The combination of these surface and subsurface conditions led to changes in the received level of the sources that exceeded 60 dB and showed a distinct spacio-temporal dependence, which was correlated with the locations of the sources in the basin. This paper seeks to quantify the observed variability in the received signals through propagation modeling using spatially sparse environmental measurements.
PubMed ID
33003894 View in PubMed
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