Unsupervised classification identifies coherent thermohaline structures in the Weddell Gyre region
The Weddell Gyre is a major feature of the Southern Ocean and an important component of the planetary climate system; it regulates air–sea exchanges, controls the formation of deep and bottom waters, and hosts upwelling of relatively warm subsurface waters. It is characterised by low sea surface tem...
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ftdoajarticles:oai:doaj.org/article:a48faabead7f437ca02fc928ebbd35aa 2023-07-16T04:00:49+02:00 Unsupervised classification identifies coherent thermohaline structures in the Weddell Gyre region D. C. Jones M. Sonnewald S. Zhou U. Hausmann A. J. S. Meijers I. Rosso L. Boehme M. P. Meredith A. C. Naveira Garabato 2023-06-01T00:00:00Z https://doi.org/10.5194/os-19-857-2023 https://doaj.org/article/a48faabead7f437ca02fc928ebbd35aa EN eng Copernicus Publications https://os.copernicus.org/articles/19/857/2023/os-19-857-2023.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 doi:10.5194/os-19-857-2023 1812-0784 1812-0792 https://doaj.org/article/a48faabead7f437ca02fc928ebbd35aa Ocean Science, Vol 19, Pp 857-885 (2023) Geography. Anthropology. Recreation G Environmental sciences GE1-350 article 2023 ftdoajarticles https://doi.org/10.5194/os-19-857-2023 2023-06-25T00:34:39Z The Weddell Gyre is a major feature of the Southern Ocean and an important component of the planetary climate system; it regulates air–sea exchanges, controls the formation of deep and bottom waters, and hosts upwelling of relatively warm subsurface waters. It is characterised by low sea surface temperatures, ubiquitous sea ice formation, and widespread salt stratification that stabilises the water column. Observing the Weddell Gyre is challenging, as it is extremely remote and largely covered with sea ice. At present, it is one of the most poorly sampled regions of the global ocean, highlighting the need to extract as much value as possible from existing observations. Here, we apply a profile classification model (PCM), which is an unsupervised classification technique, to a Weddell Gyre profile dataset to identify coherent regimes in temperature and salinity. We find that, despite not being given any positional information, the PCM identifies four spatially coherent thermohaline domains that can be described as follows: (1) a circumpolar class, (2) a transition region between the circumpolar waters and the Weddell Gyre, (3) a gyre edge class with northern and southern branches, and (4) a gyre core class. PCM highlights, in an objective and interpretable way, both expected and underappreciated structures in the Weddell Gyre dataset. For instance, PCM identifies the inflow of Circumpolar Deep Water (CDW) across the eastern boundary, the presence of the Weddell–Scotia Confluence waters, and structured spatial variability in mixing between Winter Water and CDW. PCM offers a useful complement to existing expertise-driven approaches for characterising the physical configuration and variability of oceanographic regions, helping to identify coherent thermohaline structures and the boundaries between them. Article in Journal/Newspaper Sea ice Southern Ocean Directory of Open Access Journals: DOAJ Articles Southern Ocean Weddell Ocean Science 19 3 857 885 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
spellingShingle |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 D. C. Jones M. Sonnewald S. Zhou U. Hausmann A. J. S. Meijers I. Rosso L. Boehme M. P. Meredith A. C. Naveira Garabato Unsupervised classification identifies coherent thermohaline structures in the Weddell Gyre region |
topic_facet |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
description |
The Weddell Gyre is a major feature of the Southern Ocean and an important component of the planetary climate system; it regulates air–sea exchanges, controls the formation of deep and bottom waters, and hosts upwelling of relatively warm subsurface waters. It is characterised by low sea surface temperatures, ubiquitous sea ice formation, and widespread salt stratification that stabilises the water column. Observing the Weddell Gyre is challenging, as it is extremely remote and largely covered with sea ice. At present, it is one of the most poorly sampled regions of the global ocean, highlighting the need to extract as much value as possible from existing observations. Here, we apply a profile classification model (PCM), which is an unsupervised classification technique, to a Weddell Gyre profile dataset to identify coherent regimes in temperature and salinity. We find that, despite not being given any positional information, the PCM identifies four spatially coherent thermohaline domains that can be described as follows: (1) a circumpolar class, (2) a transition region between the circumpolar waters and the Weddell Gyre, (3) a gyre edge class with northern and southern branches, and (4) a gyre core class. PCM highlights, in an objective and interpretable way, both expected and underappreciated structures in the Weddell Gyre dataset. For instance, PCM identifies the inflow of Circumpolar Deep Water (CDW) across the eastern boundary, the presence of the Weddell–Scotia Confluence waters, and structured spatial variability in mixing between Winter Water and CDW. PCM offers a useful complement to existing expertise-driven approaches for characterising the physical configuration and variability of oceanographic regions, helping to identify coherent thermohaline structures and the boundaries between them. |
format |
Article in Journal/Newspaper |
author |
D. C. Jones M. Sonnewald S. Zhou U. Hausmann A. J. S. Meijers I. Rosso L. Boehme M. P. Meredith A. C. Naveira Garabato |
author_facet |
D. C. Jones M. Sonnewald S. Zhou U. Hausmann A. J. S. Meijers I. Rosso L. Boehme M. P. Meredith A. C. Naveira Garabato |
author_sort |
D. C. Jones |
title |
Unsupervised classification identifies coherent thermohaline structures in the Weddell Gyre region |
title_short |
Unsupervised classification identifies coherent thermohaline structures in the Weddell Gyre region |
title_full |
Unsupervised classification identifies coherent thermohaline structures in the Weddell Gyre region |
title_fullStr |
Unsupervised classification identifies coherent thermohaline structures in the Weddell Gyre region |
title_full_unstemmed |
Unsupervised classification identifies coherent thermohaline structures in the Weddell Gyre region |
title_sort |
unsupervised classification identifies coherent thermohaline structures in the weddell gyre region |
publisher |
Copernicus Publications |
publishDate |
2023 |
url |
https://doi.org/10.5194/os-19-857-2023 https://doaj.org/article/a48faabead7f437ca02fc928ebbd35aa |
geographic |
Southern Ocean Weddell |
geographic_facet |
Southern Ocean Weddell |
genre |
Sea ice Southern Ocean |
genre_facet |
Sea ice Southern Ocean |
op_source |
Ocean Science, Vol 19, Pp 857-885 (2023) |
op_relation |
https://os.copernicus.org/articles/19/857/2023/os-19-857-2023.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 doi:10.5194/os-19-857-2023 1812-0784 1812-0792 https://doaj.org/article/a48faabead7f437ca02fc928ebbd35aa |
op_doi |
https://doi.org/10.5194/os-19-857-2023 |
container_title |
Ocean Science |
container_volume |
19 |
container_issue |
3 |
container_start_page |
857 |
op_container_end_page |
885 |
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1771550042212007936 |