The estuarine environment often hosts a salt wedge, the stratification of which is a function of the tide's range and speed of advance, river discharge volumetric flow rate, and river mouth morphology. Competing effects of temperature and salinity on sound speed in this stratified environment control the degree of acoustic refraction occurring along an acoustic path. A field experiment was carried out in the Columbia River Estuary to test the hypothesis: the estuarine salt wedge is acoustically observable in terms of low-to-mid-frequency acoustic propagation. Linear frequency-modulated acoustic signals in the 500–2000 Hz band were transmitted during the advance and retreat of the salt wedge during May 27–29, 2013. Results demonstrate that the salt wedge front is the dominant physical mechanism controlling acoustic propagation in this environment: received signal energy is relatively stable before and after the passage of the salt wedge front when the acoustic path consists of a single medium (either entirely fresh water or entirely salt water), and suffers a 10–15 dB loss and increased variability during salt wedge front passage. Physical parameters and acoustic propagation modeling corroborate and inform the acoustic observations.
References
1.
Chen
, C.-T.
, and Millero
, F. J.
(1977
). “Speed of sound in seawater at high pressures
,” J. Acoust. Soc. Am.
62
, 1129
–1135
.2.
Diachock
, O.
(1999
). “Effects of absorbtivity due to fish on transmission loss in shallow water
,” J. Acoust. Soc. Am.
105
(4
), 2107
–2128
.3.
Di Iorio
, D.
, and Farmer
, D. M.
(1994
). “Path-averaged turbulent dissipation measurements using high-frequency acoustical scintillation analysis
,” J. Acoust. Soc. Am.
96
(2
), 1056
–1069
.4.
Dong
, L.
, Wang
, D.
, Wang
, K.
, Li
, S.
, Dong
, S.
, Zhao
, X.
, Akamatsu
, T.
, and Kimura
, S.
(2011
). “Passive acoustic survey of Yangtze finless porpoises using a cargo ship as a moving platform
,” J. Acoust. Soc. Am.
130
(4
), 2285
–2292
.5.
Dyer
, Keith
(1998
). Estuaries: A Physical Introduction
(Wiley
, New York
), Chap. 1
, pp. 5
–25
.6.
Elias
, E. P. L.
, Gelfenbaum
, G.
, and Van der Westhuysen
, A. J.
(2012
). “Validation of a coupled wave-flow model in a high-energy setting: The mouth of the Columbia River
,” J. Geophys. Res.
117
, C09011
, doi:.7.
Etter
, Paul C.
(2003
). Underwater Acoustic Modeling and Simulation
(Spon Press
, London
), Chap. 4.8.
Fillinger
, L.
, Sutin
, A.
, and Sedunov
, A.
(2011
). “Acoustic ship signature measurements by cross-correlation method
,” J. Acoust. Soc. Am.
129
(2
), 774
–778
.9.
Gelfenbaum
, G.
(1983
). “Suspended-sediment response to semidiumal and fortnightly tidal variations in a mesotidal estuary: Columbia River, USA
,” Marine Geol.
52
, 39
–57
.10.
Gelfenbaum
, G.
, Elias
, E.
, Stevens
, A.
, MacMahan
, J.
, Reniers
, A.
, and Sherwood
, C.
(2014
). “Impacts of large-scale morphology and bedforms on inlet dynamics: Mouth of the Columbia River, USA
,” in Proceedings of the 17th Physics of Estuaries and Coastal Seas (PECS) Conference
, Porto de Galinhas, Pernambuco, Brazil, 19–24 October.11.
Geyer
, Rocky
(2014
). (personal communication).12.
Haviland-Howell
, G.
, Frankel
, A. S.
, Powell
, C. M.
, Bocconcelli
, A.
, Herman
, R. L.
, and Sayigh
, L. S.
(2007
). “Recreational boating traffic: A chronic source of anthropogenic noise in the Wilmington, North Carolina Intracoastal Waterway
,” J. Acoust. Soc. Am.
122
(1
), 151
–160
.13.
Jay
, D. A.
, and Smith
, J. D.
(1990
). “Circulation, density distribution and spring-neap transitions in the Columbia River estuary
,” Prog. Oceanogr.
25
, 81
–112
.14.
Lavery
, A. C.
, Geyer
, W. R.
, and Scully
, M. E.
(2013
). “Broadband acoustic quantification of stratified turbulence
,” J. Acoust. Soc. Am.
134
(1
), 40
–54
.15.
McConnell
, S. O.
, Schilt
, M. P.
, and Dworski
, J. G.
(1992
). “Ambient noise measurements from 100 Hz to 80 kHz in an Alaskan fjord
,” J. Acoust. Soc. Am.
91
(4
), 1990
–2003
.16.
McNeil
, C. L.
, Shcherbina
, A.
, Litchendorf
, T.
, Sanford
, T. B.
, Martin
, D.
, Bapista
, A. M.
, Lopez
, J.
, and Crump
, B.
(2012
). “Observations of the Columbia River salt wedge and estuarine turbidity maximum using AUVs
,” Abstract OS11G-07, presented at the 2012 Fall Meeting, AGU
, San Francisco, CA, 3–7 December.17.
Neal
, V. T.
(1972
). “Physical aspects of the Columbia River and its estuary
,” in The Columbia River Estuary and Adjacent Ocean Waters
, edited by A. T.
Pruter
and D. L.
Alverson
(University of Washington Press
, Seattle, WA
), pp. 19
–40
.18.
Poikonen
, A. A.
(2010
). “High-frequency wind-driven ambient noise in shallow brackish water: Measurements and spectra
,” J. Acoust. Soc. Am.
128
(5
), EL242
–EL247
.19.
Porter
, M. B.
, and Bucker
, H. P.
(1987
). “Gaussian beam tracing for computing ocean acoustic fields
,” J. Acoust. Soc. Am.
82
(4
), 1349
–1359
.20.
Radhakrishnan
, S.
(2009
). “Acoustic propagation in the Hudson River Estuary: Analysis of experimental measurements and numerical modeling results
,” Ph.D. dissertation, Stevens Institute of Technology, Publication Number 3351563.21.
Reeder
, D. Benjamin
(2013
). “Acoustical characterization of the estuarine salt wedge
,” POMA
19
, 005004
.22.
Reeder
, D. Benjamin
, and Stanton
, T. K.
(2004
). “Acoustic scattering by axisymmetric finite-length bodies: An extension of a 2-dimensional conformal mapping method
,” J. Acoust. Soc. Am.
116
(2
), 729
–746
.23.
Roh
, H.-S.
, Sutin
, A.
, and Bunin
, B.
(2008
). “Determination of acoustic attenuation in the Hudson River Estuary by means of ship noise observations
,” J. Acoust. Soc. Am.
123
(6
), EL139
–EL143
.24.
Sherwood
, C. R.
, and Creager
, J. S.
(1990
). “Sedimentary geology of the Columbia River estuary
,” Prog. Oceanogr.
25
, 15
–79
.25.
Sherwood
, C. R.
, Jay
, D. A.
, Harvey
, R. B.
, Hamilton
, P.
, and Simenstad
, C. A.
(1990
). “Historical changes in the Columbia River estuary
,” Prog. Oceanogr.
25
, 299
–352
.26.
Stolkin
, R.
, Sutin
, A.
, Radhakrishnan
, S.
, Bruno
, M.
, Fullerton
, B.
, Ekimov
, A.
, and Raftery
, M.
(2006
). “Feature based passive acoustic detection of underwater threats
,” in Photonics for Port and Harbor Security II
, Proceedings of SPIE, edited by M.
DeWeert
, T. T.
Saito
, and H. L.
Guthmuller
, Vol. 6204, p. 620408
.27.
Thomson
, J.
, Horner-Devine
, A. R.
, Zippel
, S.
, Rusch
, C.
, and Geyer
, W.
(2014
). “Wave breaking turbulence at the offshore front of the Columbia River Plume
,” Geophys. Res. Lett.
41
, 8987
–8993
, doi:.28.
van Walree
, P. A.
, Neasham
, J. A.
, and Schrijver
, M. C.
(2007
). “Coherent acoustic communication in a tidal estuary with busy shipping traffic
,” J. Acoust. Soc. Am.
122
(6
), 3495
–3506
.29.
Vracar
, M. S.
, and Miomir
, M.
(2011
). “Ambient noise in large rivers (L)
,” J. Acoust. Soc. Am.
130
(4
), 1787
–1791
.30.
Wysocki
, L. E.
, Amoser
, S.
, and Ladich
, F.
(2007
). “Diversity of ambient noise in European freshwater habitats: Noise levels, spectral profiles, and impact on fishes
,” J. Acoust. Soc. Am.
121
(5
), 2559
–2566
.31.
Xie
, Y.
(2000
). “A range-dependent echo-association algorithm and its application in split-beam sonar tracking of migratory salmon in the Fraser River watershed
,” J. Ocean Eng.
25
(3
), 387
–398
.32.
Zhou
, J.-X.
, Zhang
, X.-Z.
, and Knobles
, D. P.
(2009
). “Low-frequency geoacoustic model for the effective properties of sandy seabottoms
,” J. Acoust. Soc. Am.
125
(5
), 2847
–2866
.33.
Zhu
, X.-H.
, Zhang
, C.
, Wu
, Q.
, Fan
, X.
, and Li
, Bo
(2010
). “Acoustic measurement of tidal bores in the Qiantang River, China
,” in Proceedings of the 3rd International Congress on Image and Signal Processing (CISP)
, pp. 3839
–3843
.2016
U.S. Government
You do not currently have access to this content.
