A Modal Approach to Arctic Noise Modelling with Implied Vertical Coherence
Analytic formulas of the modal attenuation coefficients appropriate for deep Arctic under-ice conditions, and modal energy partitioning of ambient noise sources are proposed. These functions can be used, together with various assumed spatial and temporal distribution functions to calculate various s...
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ftdtic:ADA192966 2023-05-15T14:53:33+02:00 A Modal Approach to Arctic Noise Modelling with Implied Vertical Coherence Williams, R B NAVAL OCEAN SYSTEMS CENTER SAN DIEGO CA 1988-02 text/html http://www.dtic.mil/docs/citations/ADA192966 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA192966 en eng http://www.dtic.mil/docs/citations/ADA192966 APPROVED FOR PUBLIC RELEASE DTIC AND NTIS Crystallography *AMBIENT NOISE *ACOUSTIC ATTENUATION ARCTIC REGIONS COEFFICIENTS COHERENCE COMPARISON CORRELATION DISTRIBUTION FUNCTIONS ENERGY FREQUENCY LENGTH MATHEMATICAL MODELS SENSITIVITY SOURCES SPATIAL DISTRIBUTION STATISTICAL FUNCTIONS UNDERICE VALIDATION VERTICAL ORIENTATION TIME Modal energy PE62435N WUDN307376 Text 1988 ftdtic 2016-02-19T11:07:40Z Analytic formulas of the modal attenuation coefficients appropriate for deep Arctic under-ice conditions, and modal energy partitioning of ambient noise sources are proposed. These functions can be used, together with various assumed spatial and temporal distribution functions to calculate various statistical ambient noise functions, such as vertical coherence. Vertical noise data between 15 and 50 Hz have been analyzed for model comparison, using a bandwidth of about 5 Hz. These data show that the vertical coherence usually has a sin x/x dependence, with the first zero crossing at one wavelength. Sometimes, however zero crossing lengths of more than two wavelengths are observed. Longer correlation lengths are consistent with much of the noise energy radiating from a small region, although other interpretations are possible. Initial simple model calculations show agreement with the data. A strong nearby source of noise will cause the correlation to lengthen, while several more distant sources support the one wavelength zero crossing result. Initial sensitivity calculations, however, show that the vertical coherence function by itself is not a good validator of the model functions. Other statistics will be sought to further examine model validity. (Abstract only) Text Arctic Defense Technical Information Center: DTIC Technical Reports database Arctic |
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Open Polar |
collection |
Defense Technical Information Center: DTIC Technical Reports database |
op_collection_id |
ftdtic |
language |
English |
topic |
Crystallography *AMBIENT NOISE *ACOUSTIC ATTENUATION ARCTIC REGIONS COEFFICIENTS COHERENCE COMPARISON CORRELATION DISTRIBUTION FUNCTIONS ENERGY FREQUENCY LENGTH MATHEMATICAL MODELS SENSITIVITY SOURCES SPATIAL DISTRIBUTION STATISTICAL FUNCTIONS UNDERICE VALIDATION VERTICAL ORIENTATION TIME Modal energy PE62435N WUDN307376 |
spellingShingle |
Crystallography *AMBIENT NOISE *ACOUSTIC ATTENUATION ARCTIC REGIONS COEFFICIENTS COHERENCE COMPARISON CORRELATION DISTRIBUTION FUNCTIONS ENERGY FREQUENCY LENGTH MATHEMATICAL MODELS SENSITIVITY SOURCES SPATIAL DISTRIBUTION STATISTICAL FUNCTIONS UNDERICE VALIDATION VERTICAL ORIENTATION TIME Modal energy PE62435N WUDN307376 Williams, R B A Modal Approach to Arctic Noise Modelling with Implied Vertical Coherence |
topic_facet |
Crystallography *AMBIENT NOISE *ACOUSTIC ATTENUATION ARCTIC REGIONS COEFFICIENTS COHERENCE COMPARISON CORRELATION DISTRIBUTION FUNCTIONS ENERGY FREQUENCY LENGTH MATHEMATICAL MODELS SENSITIVITY SOURCES SPATIAL DISTRIBUTION STATISTICAL FUNCTIONS UNDERICE VALIDATION VERTICAL ORIENTATION TIME Modal energy PE62435N WUDN307376 |
description |
Analytic formulas of the modal attenuation coefficients appropriate for deep Arctic under-ice conditions, and modal energy partitioning of ambient noise sources are proposed. These functions can be used, together with various assumed spatial and temporal distribution functions to calculate various statistical ambient noise functions, such as vertical coherence. Vertical noise data between 15 and 50 Hz have been analyzed for model comparison, using a bandwidth of about 5 Hz. These data show that the vertical coherence usually has a sin x/x dependence, with the first zero crossing at one wavelength. Sometimes, however zero crossing lengths of more than two wavelengths are observed. Longer correlation lengths are consistent with much of the noise energy radiating from a small region, although other interpretations are possible. Initial simple model calculations show agreement with the data. A strong nearby source of noise will cause the correlation to lengthen, while several more distant sources support the one wavelength zero crossing result. Initial sensitivity calculations, however, show that the vertical coherence function by itself is not a good validator of the model functions. Other statistics will be sought to further examine model validity. (Abstract only) |
author2 |
NAVAL OCEAN SYSTEMS CENTER SAN DIEGO CA |
format |
Text |
author |
Williams, R B |
author_facet |
Williams, R B |
author_sort |
Williams, R B |
title |
A Modal Approach to Arctic Noise Modelling with Implied Vertical Coherence |
title_short |
A Modal Approach to Arctic Noise Modelling with Implied Vertical Coherence |
title_full |
A Modal Approach to Arctic Noise Modelling with Implied Vertical Coherence |
title_fullStr |
A Modal Approach to Arctic Noise Modelling with Implied Vertical Coherence |
title_full_unstemmed |
A Modal Approach to Arctic Noise Modelling with Implied Vertical Coherence |
title_sort |
modal approach to arctic noise modelling with implied vertical coherence |
publishDate |
1988 |
url |
http://www.dtic.mil/docs/citations/ADA192966 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA192966 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
DTIC AND NTIS |
op_relation |
http://www.dtic.mil/docs/citations/ADA192966 |
op_rights |
APPROVED FOR PUBLIC RELEASE |
_version_ |
1766325135215689728 |