NDLI: Acoustic energy attenuation of 3DVSP airgun arrays operating in Long Beach Harbor

Content Provider	IEEE Xplore Digital Library
Author	Hamilton, M.J. Sternlicht, D.D. Heaney, K.D. Teranishi, A.M. Castile, B.D. Chermak, A. Barrow, H.A. Barker, R.L.
Copyright Year	2003
Description	Author affiliation: Orincon Corp., San Diego, CA, USA (Hamilton, M.J.; Sternlicht, D.D.; Heaney, K.D.; Teranishi, A.M.; Castile, B.D.)
Abstract	Increased awareness of the disruptive impact high-power sonars and airguns potentially have on marine mammal populations has resulted in the adoption of flexible survey protocols, which account for movements of these animals through the region. To effectively modulate source transmissions and maintain adequate standoff distances, accurate estimates of range-dependent sound pressure levels (SPLs) are required. To determine safe ranges of airgun operation during a three dimensional vertical seismic profile survey (3DVSP) in Long Beach Harbor, stationary hydrophones were deployed to measure SPLs received from 160 in/sup 3/, 320 in/sup 3/ and 560 in/sup 3/ airgun arrays fired along a 5 km track. Recordings from bow and stern source boat aspects are analyzed for pulse energy, pulse duration, peak instantaneous pressure, and rms pressure over the pulse duration. For each airgun array and aspect combination, range-limited linear regression curve fits are carried out to characterize transmission loss. Distances at which the SPL drops below 190 dB, 180 dB, and 160 dB rms re: 1 /spl mu/Pa are determined, where operation of airguns at distances from marine mammals greater than the 160 dB range is mandated by the National Marine Fisheries Service (NMFS). For the 160 in/sup 3/ array, the bow aspect 160 dB level is estimated at 1279 m. For the 320 in/sup 3/ array, the bow and stern aspect 160 dB levels are estimated at 1712 m and 1916 m respectively. For the 560 in/sup 3/ array, the bow and stern aspect 160 dB levels are estimated at 2057 m and 2672 m respectively. The data collection and analysis techniques described in this paper rapidly and inexpensively determine NMFS compliant airgun operating procedures.
Sponsorship	Dept. of the Navy Sci. and Technol. Coalition for Enhanced Marine Resources Orincon Ceros Harbour Offshore Inc
Starting Page	76
Ending Page	80
File Size	342188
Page Count	5
File Format	PDF
ISBN	0933957300
DOI	10.1109/OCEANS.2003.178524
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2003-09-22
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	MTS
Subject Keyword	Attenuation Acoustic arrays Protocols Animals Sonar equipment Seismic measurements Boats Linear regression Propagation losses Aquaculture
Content Type	Text
Resource Type	Article

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