Unraveling the thermohaline structure of the Southern Ocean using functional data analysis
The Southern Ocean connects the Indian, Pacific and Atlantic Oceans and provides a direct pathway to exchange mass, heat and salt across the Global Ocean, therefore playing an important role in the global climate system. Due to the complexity of its structure and the general inadequacy of its sampli...
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Stockholms universitet, Meteorologiska institutionen (MISU)
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ftstockholmuniv:oai:DiVA.org:su-161034 2023-05-15T13:56:08+02:00 Unraveling the thermohaline structure of the Southern Ocean using functional data analysis Pauthenet, Etienne 2018 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-161034 eng eng Stockholms universitet, Meteorologiska institutionen (MISU) Stockholm : Department of Meteorology, Stockholm University orcid:0000-0002-0531-3810 http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-161034 urn:isbn:978-91-7797-496-3 urn:isbn:978-91-7797-497-0 info:eu-repo/semantics/openAccess Southern Ocean Front Water mass Antarctic Polar Front Descriptive Physical Oceanography Functional Principal Component Analysis Elephant Seal Biologging Oceanography Hydrology and Water Resources Oceanografi hydrologi och vattenresurser Doctoral thesis, comprehensive summary info:eu-repo/semantics/doctoralThesis text 2018 ftstockholmuniv 2023-02-23T21:42:57Z The Southern Ocean connects the Indian, Pacific and Atlantic Oceans and provides a direct pathway to exchange mass, heat and salt across the Global Ocean, therefore playing an important role in the global climate system. Due to the complexity of its structure and the general inadequacy of its sampling, both in time and space, it remains a challenge to describe and visualize the three dimensional pattern of its circulation and the associated tracer distribution (temperature, salinity, oxygen or nutrients). This thesis contributes to the understanding of the thermohaline structure of the ocean and especially of the remote Southern Ocean by introducing a novel decomposition method, the Functional Principal Component Analysis applied on vertical profiles of temperature and salinity. To this end, we first normalize hydrographic profiles by using a functional spline representation. Then the statistical method of dimension reduction and feature extraction reveals the main spatial patterns of the temperature and salinity variations. The first two vertical modes contribute to 90% of the combined variance and are related to very robust structures of the Global Ocean. The first mode is mainly controlled by temperature and the second by salinity. In the Southern Ocean, the vertical modes present circumpolar patterns that can be closely related to the stratification regimes that define the circumpolar fronts. Notably the Polar Front is located at the natural boundary between the region controlled by the first (thermal) mode to the north and the second (haline) mode to the south. A mapping of the fundamental zonation is provided with an estimate of the width of the water mass boundaries. As a validation of this method, the Antarctic Polar Front is investigated further in the Indian sector using the same statistical framework. We show that the Polar Front latitudinal position varies seasonally upstream of the Kerguelen Plateau. This meandering is confirmed by hydrographic data gathered by elephant seals equipped with ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Elephant Seal Elephant Seals Southern Ocean Stockholm University: Publications (DiVA) Antarctic Indian Kerguelen Pacific Southern Ocean The Antarctic |
institution |
Open Polar |
collection |
Stockholm University: Publications (DiVA) |
op_collection_id |
ftstockholmuniv |
language |
English |
topic |
Southern Ocean Front Water mass Antarctic Polar Front Descriptive Physical Oceanography Functional Principal Component Analysis Elephant Seal Biologging Oceanography Hydrology and Water Resources Oceanografi hydrologi och vattenresurser |
spellingShingle |
Southern Ocean Front Water mass Antarctic Polar Front Descriptive Physical Oceanography Functional Principal Component Analysis Elephant Seal Biologging Oceanography Hydrology and Water Resources Oceanografi hydrologi och vattenresurser Pauthenet, Etienne Unraveling the thermohaline structure of the Southern Ocean using functional data analysis |
topic_facet |
Southern Ocean Front Water mass Antarctic Polar Front Descriptive Physical Oceanography Functional Principal Component Analysis Elephant Seal Biologging Oceanography Hydrology and Water Resources Oceanografi hydrologi och vattenresurser |
description |
The Southern Ocean connects the Indian, Pacific and Atlantic Oceans and provides a direct pathway to exchange mass, heat and salt across the Global Ocean, therefore playing an important role in the global climate system. Due to the complexity of its structure and the general inadequacy of its sampling, both in time and space, it remains a challenge to describe and visualize the three dimensional pattern of its circulation and the associated tracer distribution (temperature, salinity, oxygen or nutrients). This thesis contributes to the understanding of the thermohaline structure of the ocean and especially of the remote Southern Ocean by introducing a novel decomposition method, the Functional Principal Component Analysis applied on vertical profiles of temperature and salinity. To this end, we first normalize hydrographic profiles by using a functional spline representation. Then the statistical method of dimension reduction and feature extraction reveals the main spatial patterns of the temperature and salinity variations. The first two vertical modes contribute to 90% of the combined variance and are related to very robust structures of the Global Ocean. The first mode is mainly controlled by temperature and the second by salinity. In the Southern Ocean, the vertical modes present circumpolar patterns that can be closely related to the stratification regimes that define the circumpolar fronts. Notably the Polar Front is located at the natural boundary between the region controlled by the first (thermal) mode to the north and the second (haline) mode to the south. A mapping of the fundamental zonation is provided with an estimate of the width of the water mass boundaries. As a validation of this method, the Antarctic Polar Front is investigated further in the Indian sector using the same statistical framework. We show that the Polar Front latitudinal position varies seasonally upstream of the Kerguelen Plateau. This meandering is confirmed by hydrographic data gathered by elephant seals equipped with ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Pauthenet, Etienne |
author_facet |
Pauthenet, Etienne |
author_sort |
Pauthenet, Etienne |
title |
Unraveling the thermohaline structure of the Southern Ocean using functional data analysis |
title_short |
Unraveling the thermohaline structure of the Southern Ocean using functional data analysis |
title_full |
Unraveling the thermohaline structure of the Southern Ocean using functional data analysis |
title_fullStr |
Unraveling the thermohaline structure of the Southern Ocean using functional data analysis |
title_full_unstemmed |
Unraveling the thermohaline structure of the Southern Ocean using functional data analysis |
title_sort |
unraveling the thermohaline structure of the southern ocean using functional data analysis |
publisher |
Stockholms universitet, Meteorologiska institutionen (MISU) |
publishDate |
2018 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-161034 |
geographic |
Antarctic Indian Kerguelen Pacific Southern Ocean The Antarctic |
geographic_facet |
Antarctic Indian Kerguelen Pacific Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Elephant Seal Elephant Seals Southern Ocean |
genre_facet |
Antarc* Antarctic Elephant Seal Elephant Seals Southern Ocean |
op_relation |
orcid:0000-0002-0531-3810 http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-161034 urn:isbn:978-91-7797-496-3 urn:isbn:978-91-7797-497-0 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1766263416470634496 |