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Vertical line array measurements of ambient noise in the North Pacific

TitleVertical line array measurements of ambient noise in the North Pacific
Publication TypeJournal Article
Year of Publication2017
AuthorsFarrokhrooz M., Wage K.E, Dzieciuch M.A, Worcester P.F
JournalJournal of the Acoustical Society of America
Date Published2017/03
Type of ArticleArticle
ISBN Number0001-4966
Accession NumberWOS:000398962500042
Keywordsarrivals; deep; depth dependence; fourier-transform; long-range; low-frequency; ocean acoustic propagation; sea-floor; surface; wind

Shipping noise and wind are the dominant sources of ocean noise in the frequency band between 20 and 500 Hz. This paper analyzes noise in that band using data from the SPICEX experiment, which took place in the North Pacific in 2004-2005, and compares the results with other North Pacific experiments. SPICEX included vertical arrays with sensors above and below the surface conjugate depth, facilitating an analysis of the depth dependence of ambient noise. The paper includes several key results. First, the 2004-05 noise levels at 50 Hz measured in SPICEX had not increased relative to levels measured by Morris [(1978). J. Acoust. Soc. Am. 64, 581-590] at a nearby North Pacific site three decades earlier, but rather were comparable to those levels. Second, at 50Hz the noise below the conjugate depth decreases at a rate of -9.9 dB/km, which is similar to the rate measured by Morris and much less than the rate measured by Gaul, Knobles, Shooter, and Wittenborn [(2007). IEEE J. Ocean. Eng. 32, 497-512] for the CHURCH OPAL experiment. Finally, the paper describes the seasonal trends in noise over the year-long time series of the measurements. (C) 2017 Acoustical Society of America.

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