Deep water towed array measurements at close range

During the North Pacific Acoustic Laboratory Philippine Sea 2009 experiment, towed array receptions were made from a towed source as the two ships transited from a separation of several Convergence Zones through a Closest Point of Approach at 3 km. A combination of narrowband tones and broadband pul...

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Bibliographic Details
Published in:The Journal of the Acoustical Society of America 2013-10, Vol.134 (4), p.3230-3241
Main Authors: Heaney, Kevin D, Campbell, Richard L, Murray, James J, Baggeroer, Arthur B, Scheer, Eddie K, Stephen, Ralph A, D'Spain, Gerald L, Mercer, James A
Format: Article
Language:English
Subjects:
Acoustics - instrumentation
Doppler Effect
Geologic Sediments
Models, Theoretical
Motion
Oceanography - instrumentation
Oceanography - methods
Oceans and Seas
Scattering, Radiation
Seawater
Signal Processing, Computer-Assisted
Sound
Sound Spectrography
Surface Properties
Time Factors
Transducers
Water Movements
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Summary:During the North Pacific Acoustic Laboratory Philippine Sea 2009 experiment, towed array receptions were made from a towed source as the two ships transited from a separation of several Convergence Zones through a Closest Point of Approach at 3 km. A combination of narrowband tones and broadband pulses were transmitted covering the frequency band 79-535 Hz. The received energy arrives from two general paths-direct path and bottom bounce. Bearing-time records of the narrowband arrivals at times show a 35° spread in the angle of arrival of the bottom bounce energy. Doppler processing of the tones shows significant frequency spread of the bottom bounce energy. Two-dimensional modeling using measured bathymetry, a geoacoustic parameterization based upon the geological record, and measured sound-speed field was performed. Inclusion of the effects of seafloor roughness and surface waves shows that in-plane scattering from rough interfaces can explain much of the observed spread in the arrivals. Evidence of out-of-plane scattering does exist, however, at short ranges. The amount of out-of-plane scattering is best observed in the broadband impulse-beam response analysis, which in-plane surface roughness modeling cannot explain.
ISSN:0001-4966
1520-8524
DOI:10.1121/1.4818869