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.
REFERENCES
1.
Anagnostou
, M. N.
, Nystuen
, J. A.
, Anagnostou
, E. N.
, Nikolopoulos
, E. I.
, and Amitai
, E.
(2008
). “Evaluation of underwater rainfall measurements during the Ionian Sea rainfall experiment
,” IEEE Trans. Geosci. Remote Sens.
46
, 2936
–2946
.2.
Barclay
, D. R.
, Simonet
, F.
, and Buckingham
, M. J.
(2009
). “Deep sound: A free-falling sensor platform for depth-profiling ambient noise in the deep ocean
,” Mar. Technol. Soc. J.
43
, 144
–150
.3.
Bom
, N.
(1969
). “Effect of rain on underwater noise level
,” J. Acoust. Soc. Am.
45
, 150
–156
.26.
Buckingham
, M. J.
(2011
). “On the two-point cross-correlation function of anisotropic, spatially homogeneous ambient noise in the ocean and its relationship to the Green's function,” J. Acoust. Soc. Am.
129
, 3562
–3576
.4.
Cox
, H.
(1973
). “Spatial correlation in arbitrary noise fields with application to ambient sea noise
,” J. Acoust. Soc. Am.
54
, 1289
–1301
.27.
Cron
, B. F.
, and Sherman
, C. H.
(1962
). “Spatial correlation functions for various noise models,” J. Acoust. Soc. Am.
34
, 1732
–1736
.28.
Cron
, B. F.
, and Sherman
, C. H.
(1965
). “Addendum: Spatial correlation functions for various noise models,” J. Acoust. Soc. Am.
38
, 885
.5.
Dorman
, L. M.
, Schreiner
, A. E.
, Bibee
, L. D.
, and Hildebrand
, J. A.
(1993
). “Deep-water seafloor array observations of seismo-acoustic noise in the eastern Pacific and comparisons with wind and swell
,” in Natural Physical Sources of Underwater Sound
(Kluwer
, Dordrecht
), pp.165
–174
.6.
Finger
, R. A.
, Abbagnaro
, L. A.
, and Bauer
, B. B.
(1979
). “Measurements of low-velocity flow noise on pressure and pressure gradient hydrophones
,” J. Acoust. Soc. Am.
65
, 1407
–1412
.7.
Fofonoff
, N. P.
, and Millard
, R. C.
(1983
). “Algorithms for computation of fundamental properties of seawater
,” UNESCO Technical Papers in Marine Science, Report No. 44 (UNESCO, Place du Fontenoy, Paris), pp. 1
–54
.8.
Franz
, G. J.
(1959
). “Splashes as sources of sound in liquids
,” J. Acoust. Soc. Am.
31
, 1080
–1096
.9.
Gaul
, R. D.
, Knobles
, D. P.
, Shooter
, J. A.
, and Wittenborn
, A. F.
(2007
). “Ambient noise analysis of deep-ocean measurements in the Northeast Pacific
,” IEEE J. Ocean Eng.
32
, 497
–512
.10.
Ma
, B. B.
, and Nystuen
, J. A.
(2005
). “Passive acoustic detection and measurement of rainfall at sea
,” J. Atmos. Ocean. Technol.
22
, 1225
–1248
.11.
Marshall
, S. W.
(2005
). “Depth dependence of ambient noise
,” IEEE J. Ocean. Eng.
30
, 275
–281
.12.
McCreery
, C. S.
, Duennebier
, F. K.
, and Sutton
, G. H.
(1993
). “Correlation of deep ocean noise (0.4–30 Hz) with wind, and the Holu Spectrum-A worldwide constant
,” J. Acoust. Soc. Am.
93
, 2639
–2648
.13.
McGrath
, J. R.
, Griffin
, O. M.
, and Finger
, R. A.
(1977
). “Infrasonic flow-noise measurements using an H-58 omnidirectional cylindrical hydrophone
,” J. Acoust. Soc. Am.
61
, 390
–396
.14.
Medwin
, H.
, Nystuen
, J. A.
, Jacobus
, P. W.
, Ostwald
, L. H.
, and Snyder
, D. E.
(1992
). “The anatomy of underwater rain noise
,” J. Acoust. Soc. Am.
92
, 1613
–1623
.15.
Morris
, G. B.
(1978
). “Depth dependence of ambient noise in the northeastern Pacific Ocean
,” J. Acoust. Soc. Am.
64
, 581
–590
.16.
Nocedal
, J.
, and Wright
, S. J.
(1999
). Numerical Optimization
(Springer
, New York)
, 636
pp.17.
Nystuen
, J. A.
(2005
). “Using underwater sound to measure raindrop size distribution
,” in Sounds in the Sea: From Ocean Acoustics to Acoustical Oceanography
(Cambridge University Press
, Cambridge
), pp. 341
–352
.18.
Nystuen
, J. A.
, McGlothin
, C. C.
, and Cook
, M. S.
(1993
). “The underwater sound generated by heavy rainfall
,” J. Acoust. Soc. Am.
93
, 3169
–3177
.19.
Nystuen
, J. A.
, and Medwin
, H.
(1995
). “Underwater sound produced by rainfall: Secondary splashes of aerosols
,” J. Acoust. Soc. Am.
97
, 1606
–1613
.20.
Pumphrey
, H. C.
, Crum
, L. A.
, and Bjorno
, L.
(1989
). “Underwater sound produced by individual drop impacts and rainfall
,” J. Acoust. Soc. Am.
85
, 1518
–1526
.21.
Smith
, W. H. F.
(1997
). “Global sea floor topography from satellite altimetry and ship depth soundings
,” Science
277
, 1956
–1962
.22.
Sun
, C.
(2010
). “The data management system for the Global Temperature and Salinity Profile Programme
,” in OceanObs. 09: Sustained Ocean Observations and Information for Society
, Vol. 2
, edited by J.
Hall
, D. E.
Harrison
, and D.
Stammer
(ESA Publication WPP-306
, Venice, Italy
).23.
Thompson
, R. O. R. Y.
(1979
). “Coherence significance levels
,” J. Atmos. Sci.
36
, 2020
–2021
.24.
Urick
, R. J.
(1967
). Principles of Underwater Sound for Engineers
(McGraw-Hill
, New York
), pp. 293
–298
.25.
Wenz
, G. M.
(1962
). “Acoustic ambient noise in the ocean: Spectra and sources
,” J. Acoust. Soc. Am.
34
, 1936
–1956
.29.
Worcester
, P. F.
, and Spindel
, R. C.
(2005
). “The North Pacific Acoustic Laboratory
,” J. Acoust. Soc. Am.
117
, 1499
–1510
.© 2013 Acoustical Society of America.
2013
Acoustical Society of America
You do not currently have access to this content.