Under-Ice Broadband Transient Measurements and Processing

This report examines the horizontal spatial coherence of broadband acoustic energy in the frequency range 100-1200 Hz from explosive sources under the ice pack. The data were recorded on four hydrophone pairs with a nominal sensor separation of 370 m from source ranges from 3 to 25 km. Mean-square c...

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Bibliographic Details
Main Author: Meredith, Roger W.
Other Authors: NAVAL OCEANOGRAPHIC AND ATMOSPHERIC RESEARCH LAB STENNIS SPACE CENTER MS
Format: Text
Language:English
Published: 1992
Subjects:
Snow
Ice and Permafrost
Explosions
Acoustics
*SEA ICE
*UNDERWATER EXPLOSIONS
*ACOUSTIC DETECTION
SOURCES
COHERENCE
PATHS
REFLECTION
DEPTH
EXPLOSIVES
FREQUENCY BANDS
ICE
BROADBAND
BACKGROUND
SEPARATION
NOISE
MEAN
HYDROPHONES
OCEANS
RAY TRACING
UNDERWATER ACOUSTICS
ACOUSTIC VELOCITY
ANTISUBMARINE WARFARE
BACKGROUND NOISE
TRAVEL TIME
PROPAGATION
ARCTIC OCEAN
FREQUENCY
TRANSIENTS
PE62435N
WUDN496433
Arctic
Arctic Ocean
Ice
ice pack
permafrost
Sea ice
Online Access:http://www.dtic.mil/docs/citations/ADA248609
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA248609
Description
Summary:This report examines the horizontal spatial coherence of broadband acoustic energy in the frequency range 100-1200 Hz from explosive sources under the ice pack. The data were recorded on four hydrophone pairs with a nominal sensor separation of 370 m from source ranges from 3 to 25 km. Mean-square coherence is computed separately for the direct and ice-reflected propagation paths, and octave band frequency averaging reduces variability inherent in the coherence estimation associated with explosive acoustic sources. Coherence varies significantly with sensor depth, range, and frequency. Background noise coherence is also examined briefly. Changes in coherence because of under-ice reflection are smallest for the 100-200 Hz octave band, but the change may be as high as 50% for the higher frequency bands.

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