Passive acoustic monitoring of the deep ocean using ambient noise
In the ocean, changes in the speed of sound can be related to changes in water temperature. By leveraging this relationship, acoustic methods – namely acoustic tomography- have been used to monitor temperature changes in the deep ocean for the purposes of providing inputs to climate change models. T...
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Georgia Institute of Technology
2015
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ftgeorgiatech:oai:repository.gatech.edu:1853/53910 2024-06-02T08:14:21+00:00 Passive acoustic monitoring of the deep ocean using ambient noise Woolfe, Katherine F. Sabra, Karim G. Degertekin, F. Levent Di Lorenzo, Emanuele Meaud, Julien Kuperman, William Mechanical Engineering 2015-09-21T14:25:44Z application/pdf http://hdl.handle.net/1853/53910 en_US eng Georgia Institute of Technology http://hdl.handle.net/1853/53910 Acoustic Oceanography Text Dissertation 2015 ftgeorgiatech 2024-05-06T11:58:28Z In the ocean, changes in the speed of sound can be related to changes in water temperature. By leveraging this relationship, acoustic methods – namely acoustic tomography- have been used to monitor temperature changes in the deep ocean for the purposes of providing inputs to climate change models. Traditionally, these acoustic methods involve loud, active sound sources which can be logistically challenging to operate and have been criticized for potentially disturbing marine animals. Therefore, this work demonstrates a passive acoustic method - previously only used in shallow water for short monitoring durations- that uses only recordings of low-frequency (1-40 Hz) ambient noise to continuously monitor variations in deep ocean temperature with an unprecedented degree of precision and temporal resolution. Numerical simulations were conducted to show the portions of the ocean that are monitored with this passive method. This work also provides recommendations (regarding sensor placement around the world) for future development of a global passive acoustic sensor network that makes use of distant noise sources (sea-ice or seismic sources) to extract meaningful information (whether temperature, currents, etc.) about the ocean. Finally, an optimization method is proposed to overcome one of the fundamental limitations of previous applications of this passive monitoring method: tracking oceanic fluctuations that occur over short time scales. Hence, the results of this study may assist in the development of more reliable climate models that include an enhanced understanding of the ocean’s role as a global heat sink. Finally, an optimization method was proposed to enhance the emergence rate of coherent arrivals from ambient noise correlations, thus allowing this passive monitoring method to track acoustic medium fluctuations on a shorter time scale. This optimization could also be used in other applications of noise-based passive monitoring in a rapidly fluctuating medium (seismic, structural health monitoring, ... Doctoral or Postdoctoral Thesis Sea ice Georgia Institute of Technology: SMARTech - Scholarly Materials and Research at Georgia Tech Active Sound ENVELOPE(-56.167,-56.167,-63.417,-63.417) |
institution |
Open Polar |
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Georgia Institute of Technology: SMARTech - Scholarly Materials and Research at Georgia Tech |
op_collection_id |
ftgeorgiatech |
language |
English |
topic |
Acoustic Oceanography |
spellingShingle |
Acoustic Oceanography Woolfe, Katherine F. Passive acoustic monitoring of the deep ocean using ambient noise |
topic_facet |
Acoustic Oceanography |
description |
In the ocean, changes in the speed of sound can be related to changes in water temperature. By leveraging this relationship, acoustic methods – namely acoustic tomography- have been used to monitor temperature changes in the deep ocean for the purposes of providing inputs to climate change models. Traditionally, these acoustic methods involve loud, active sound sources which can be logistically challenging to operate and have been criticized for potentially disturbing marine animals. Therefore, this work demonstrates a passive acoustic method - previously only used in shallow water for short monitoring durations- that uses only recordings of low-frequency (1-40 Hz) ambient noise to continuously monitor variations in deep ocean temperature with an unprecedented degree of precision and temporal resolution. Numerical simulations were conducted to show the portions of the ocean that are monitored with this passive method. This work also provides recommendations (regarding sensor placement around the world) for future development of a global passive acoustic sensor network that makes use of distant noise sources (sea-ice or seismic sources) to extract meaningful information (whether temperature, currents, etc.) about the ocean. Finally, an optimization method is proposed to overcome one of the fundamental limitations of previous applications of this passive monitoring method: tracking oceanic fluctuations that occur over short time scales. Hence, the results of this study may assist in the development of more reliable climate models that include an enhanced understanding of the ocean’s role as a global heat sink. Finally, an optimization method was proposed to enhance the emergence rate of coherent arrivals from ambient noise correlations, thus allowing this passive monitoring method to track acoustic medium fluctuations on a shorter time scale. This optimization could also be used in other applications of noise-based passive monitoring in a rapidly fluctuating medium (seismic, structural health monitoring, ... |
author2 |
Sabra, Karim G. Degertekin, F. Levent Di Lorenzo, Emanuele Meaud, Julien Kuperman, William Mechanical Engineering |
format |
Doctoral or Postdoctoral Thesis |
author |
Woolfe, Katherine F. |
author_facet |
Woolfe, Katherine F. |
author_sort |
Woolfe, Katherine F. |
title |
Passive acoustic monitoring of the deep ocean using ambient noise |
title_short |
Passive acoustic monitoring of the deep ocean using ambient noise |
title_full |
Passive acoustic monitoring of the deep ocean using ambient noise |
title_fullStr |
Passive acoustic monitoring of the deep ocean using ambient noise |
title_full_unstemmed |
Passive acoustic monitoring of the deep ocean using ambient noise |
title_sort |
passive acoustic monitoring of the deep ocean using ambient noise |
publisher |
Georgia Institute of Technology |
publishDate |
2015 |
url |
http://hdl.handle.net/1853/53910 |
long_lat |
ENVELOPE(-56.167,-56.167,-63.417,-63.417) |
geographic |
Active Sound |
geographic_facet |
Active Sound |
genre |
Sea ice |
genre_facet |
Sea ice |
op_relation |
http://hdl.handle.net/1853/53910 |
_version_ |
1800738162834669568 |