Listening to the Oceans - Effective Techniques for Acoustic Imaging of Oceanic Structure
Submesoscale processes are known to play an important role in the vertical and lateral exchange of water masses, along with tracers such as carbon, atmosphere-ocean exchange, ocean productivity, and the mixing budget necessary to complete the overturning circulation. The challenge is to observe subm...
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University of Exeter
2023
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Online Access: | http://hdl.handle.net/10871/132638 |
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ftunivexeter:oai:ore.exeter.ac.uk:10871/132638 2023-05-15T13:57:14+02:00 Listening to the Oceans - Effective Techniques for Acoustic Imaging of Oceanic Structure Ehmen, T Sheen, Katy Watson, Andrew Brearley, Alexander Palmer, Matthew Roper, Daniel 2023 http://hdl.handle.net/10871/132638 unknown University of Exeter Faculty of Environment, Science and Economy; Centre for Geography and Environmental Science orcid:0000-0002-0102-8916 (Ehmen, Tobias) http://hdl.handle.net/10871/132638 2024-07-31 Results not published yet http://www.rioxx.net/licenses/all-rights-reserved Seismic Oceanography Acoustics Physical Oceanography Submesoscale Processes Thesis or dissertation PhD in Physical Geography Doctoral Doctoral Thesis 2023 ftunivexeter 2023-03-10T00:04:34Z Submesoscale processes are known to play an important role in the vertical and lateral exchange of water masses, along with tracers such as carbon, atmosphere-ocean exchange, ocean productivity, and the mixing budget necessary to complete the overturning circulation. The challenge is to observe submesoscale variability on sufficiently fine space and time scales. One promising approach is seismic oceanography, which applies acoustic reflection techniques, as originally developed by the hydrocarbon industry, to image temperature and salinity gradients within the water column. Here we present the first multichannel seismic images of ocean fine-structure on the eastern Falkland Plateau region of the subantarctic South Atlantic Ocean, a highly energetic confluence zone where Pacific and Antarctic waters flow via the Antarctic Circumpolar Current (ACC) to merge with waters from the Atlantic Ocean and contribute to the global overturning circulation. High-resolution (O(10m)) sections of sub-surface thermohaline structure reveal an intricate and complex pattern of oceanic fine-structure near the Polar Front: internal waves, lenses and filaments with length scales of 100m-10km in intermediate depths (up to 800 m); steep continuous filaments in deeper sections (up to 2000 m) that are influenced by interactions with bathymetry. Spectral analysis of seismic data reveals maps of increased diapycnal mixing near fronts. Furthermore, a novel approach to quantify dynamic instabilities through estimating Ertel’s Potential Vorticity and balanced Richardson angles, is presented. Another key region for the global thermohaline circulation is the Mozambique Channel, where a strong southward propagating eddy field modulates the strength of the Agulhas Current system that transfers warm, salty water into the South Atlantic Ocean. With the analysis of a 4D industry seismic data variability within the Mozambique Channel is analysed through temporal and spatial imaging of submesoscale features. Coincident closely spaced profiles provide ... Doctoral or Postdoctoral Thesis Antarc* Antarctic South Atlantic Ocean University of Exeter: Open Research Exeter (ORE) Antarctic Falkland Plateau ENVELOPE(-50.000,-50.000,-51.000,-51.000) Pacific The Antarctic |
institution |
Open Polar |
collection |
University of Exeter: Open Research Exeter (ORE) |
op_collection_id |
ftunivexeter |
language |
unknown |
topic |
Seismic Oceanography Acoustics Physical Oceanography Submesoscale Processes |
spellingShingle |
Seismic Oceanography Acoustics Physical Oceanography Submesoscale Processes Ehmen, T Listening to the Oceans - Effective Techniques for Acoustic Imaging of Oceanic Structure |
topic_facet |
Seismic Oceanography Acoustics Physical Oceanography Submesoscale Processes |
description |
Submesoscale processes are known to play an important role in the vertical and lateral exchange of water masses, along with tracers such as carbon, atmosphere-ocean exchange, ocean productivity, and the mixing budget necessary to complete the overturning circulation. The challenge is to observe submesoscale variability on sufficiently fine space and time scales. One promising approach is seismic oceanography, which applies acoustic reflection techniques, as originally developed by the hydrocarbon industry, to image temperature and salinity gradients within the water column. Here we present the first multichannel seismic images of ocean fine-structure on the eastern Falkland Plateau region of the subantarctic South Atlantic Ocean, a highly energetic confluence zone where Pacific and Antarctic waters flow via the Antarctic Circumpolar Current (ACC) to merge with waters from the Atlantic Ocean and contribute to the global overturning circulation. High-resolution (O(10m)) sections of sub-surface thermohaline structure reveal an intricate and complex pattern of oceanic fine-structure near the Polar Front: internal waves, lenses and filaments with length scales of 100m-10km in intermediate depths (up to 800 m); steep continuous filaments in deeper sections (up to 2000 m) that are influenced by interactions with bathymetry. Spectral analysis of seismic data reveals maps of increased diapycnal mixing near fronts. Furthermore, a novel approach to quantify dynamic instabilities through estimating Ertel’s Potential Vorticity and balanced Richardson angles, is presented. Another key region for the global thermohaline circulation is the Mozambique Channel, where a strong southward propagating eddy field modulates the strength of the Agulhas Current system that transfers warm, salty water into the South Atlantic Ocean. With the analysis of a 4D industry seismic data variability within the Mozambique Channel is analysed through temporal and spatial imaging of submesoscale features. Coincident closely spaced profiles provide ... |
author2 |
Sheen, Katy Watson, Andrew Brearley, Alexander Palmer, Matthew Roper, Daniel |
format |
Doctoral or Postdoctoral Thesis |
author |
Ehmen, T |
author_facet |
Ehmen, T |
author_sort |
Ehmen, T |
title |
Listening to the Oceans - Effective Techniques for Acoustic Imaging of Oceanic Structure |
title_short |
Listening to the Oceans - Effective Techniques for Acoustic Imaging of Oceanic Structure |
title_full |
Listening to the Oceans - Effective Techniques for Acoustic Imaging of Oceanic Structure |
title_fullStr |
Listening to the Oceans - Effective Techniques for Acoustic Imaging of Oceanic Structure |
title_full_unstemmed |
Listening to the Oceans - Effective Techniques for Acoustic Imaging of Oceanic Structure |
title_sort |
listening to the oceans - effective techniques for acoustic imaging of oceanic structure |
publisher |
University of Exeter |
publishDate |
2023 |
url |
http://hdl.handle.net/10871/132638 |
long_lat |
ENVELOPE(-50.000,-50.000,-51.000,-51.000) |
geographic |
Antarctic Falkland Plateau Pacific The Antarctic |
geographic_facet |
Antarctic Falkland Plateau Pacific The Antarctic |
genre |
Antarc* Antarctic South Atlantic Ocean |
genre_facet |
Antarc* Antarctic South Atlantic Ocean |
op_relation |
orcid:0000-0002-0102-8916 (Ehmen, Tobias) http://hdl.handle.net/10871/132638 |
op_rights |
2024-07-31 Results not published yet http://www.rioxx.net/licenses/all-rights-reserved |
_version_ |
1766264834760900608 |