The depth-dependence of rain noise in the Philippine Sea

TitleThe depth-dependence of rain noise in the Philippine Sea
Publication TypeJournal Article
Year of Publication2013
AuthorsBarclay DR, Buckingham MJ
JournalJournal of the Acoustical Society of America
Date Published2013/05
Type of ArticleArticle
ISBN Number0001-4966
Accession NumberWOS:000318555900022
Keywordsambient noise; deep-ocean; flow-noise; pacific; sound; spatial-correlation; splashes

During the Philippine Sea experiment in May 2009, Deep Sound, a free-falling instrument platform, descended to a depth of 5.1 km and then returned to the surface. Two vertically aligned hydrophones monitored the ambient noise continuously throughout the descent and ascent. A heavy rainstorm passed over the area during the deployment, the noise from which was recorded over a frequency band from 5 Hz to 40 kHz. Eight kilometers from the deployment site, a rain gauge on board the R/V Kilo Moana provided estimates of the rainfall rate. The power spectral density of the rain noise shows two peaks around 5 and 30 kHz, elevated by as much as 20 dB above the background level, even at depths as great as 5 km. Periods of high noise intensity in the acoustic data correlate well with the rainfall rates recovered from the rain gauge. The vertical coherence function of the rain noise has well-defined zeros between 1 and 20 kHz, which are characteristic of a localized source on the sea surface. A curve-fitting procedure yields the vertical directional density function of the noise, which is sharply peaked, accurately tracking the storm as it passed over the sensor station. (C) 2013 Acoustical Society of America.

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