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Arctic Acoustics

Arctic Acoustics . John S. Allen University of Hawaii- Manoa CIMES Annual Meeting January 28, 2013. Ice Physics and Ice Sounds. Ice Breaking –US Coast Guard. Science, Müller et al., 310 (5752): 1299, 2005. " Singing" Iceberg Recorded in Antarctica John Roach National Geographic News

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Arctic Acoustics

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  1. Arctic Acoustics John S. Allen University of Hawaii-Manoa CIMES Annual Meeting January 28, 2013

  2. Ice Physics and Ice Sounds Ice Breaking –US Coast Guard

  3. Science, Müller et al., 310 (5752): 1299, 2005 "Singing" Iceberg Recorded in Antarctica John RoachNational Geographic News November 29, 2005 They may not sound like Bing Crosby, but some icebergs can sing, scientists report. Ice breaking noise in Antarctica, Garilov and Li, 2008

  4. Previous Studies – Arctic Acoustics Miline and Ganton, Ambient Noise under Arctic Sea Ice, JASA, 36, 855, 1964 Urick, Noise of Melting Icebergs,” JASA, 42,337, 1970 • Langleben, J. Glaciology, 1969 • Miller and Schmidt, JASA, 1990 • Kapoor and Schmidt, • JASA, 1997

  5. Research Questions and Objectives Ambient Noise – Characterize Ice Cracking, Statistics, Directivity, Spectral Characteristics, Propagation, Temporal and Spatial Variability Physical Mechanisms of Ice Cracking, Different from 1990s? Acoustics Monitoring – Passive Acoustics Can the sound of ice cracking be used to facilitate target detection and tracking? Can be used for environmental monitoring alone and conjunction with other modalities? Collaboration- DARPA PROGRAM

  6. System Concept Exploitation of AN for Seabed Characterization: R-Theta Method R-Theta Method utilizes ambient noise: Wind and waves provide natural sound sources for determining bottom properties • Ambient noise advantages: • Low detectability • Broadband in frequency • Environmentally friendly • Low power consumption • In-situ measurements are possible • Two processing methods used: • R-theta (bottom loss) and passive fathometer (bottom layering) • Note: These are signal processing algorithms, not inversions. • Method resolves: • Multiple angles 0-90° • Multiple frequencies, 200-3000 Hz • Best-fit MGS curve is selected for HFBL database update Beam From Surface Bottom Bounce Beam Vertical Array GEOglider Sea Tests: NJ (Fall 09) SCORE (Spring 10) SCORE (Fall 10) WESTPAC (Summer 11) System employs passive, direct measurement vs. inversion technique.

  7. System Concept Exploitation of AN for SeabedCharacterization: Passive Fathometer Method Passive Fathometer method utilizes ambient noise beam cross-correlation: Wind and waves provide natural sound sources for determining bottom properties • Cross-correlating upward looking beam with downward produces (pulse compressed) echoes from the seabed • Provides information about seabed including seabed layering • Similar results to seismic profiling sonars (active) Beam From Surface Bottom Bounce Beam Vertical Array GEOglider Sea Tests: NJ (Fall 09) SCORE (Spring 10) SCORE (Fall 10) WESTPAC (Summer 11) System employs passive, direct measurement vs. inversion technique.

  8. Echolocation beam in odontocetes (collaboration with UH Marine Mammal Lab) • Well studied in horizontal and vertical planes • Limited to certain species

  9. Research • Recent studies indicate more intricate echolocation processes • Acoustic array allows to understand 3D composition of echolocation signals • Ability to work with a false killer whale (Pseudorca crassidens)

  10. Conclusions and Future Directions Arctic Acoustics – Differences since the 1990’s, previous studies – single hydrophone Passive Acoustics - Ambient Noise, Security and Environmental Monitoring Underwater Floating Pingers – “PIV”, Array Potential Collaboration - (DARPA Program) Multimodal Approach Potental Industry Partners - FLIR

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