The Origin and Fate of Antarctic Intermediate Water in the Southern Ocean
Using observationally based hydrographic and eddy diffusivity datasets, a volume budget analysis is per-formed to identify the main mechanisms governing the spatial and seasonal variability of Antarctic Intermediate Water (AAIW) within the density range γn = (27.25–27.7) kg m-3 in the Southern Ocean...
Published in: | Journal of Physical Oceanography |
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American Meteorological Society
2022
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Online Access: | http://hdl.handle.net/1959.4/unsworks_81963 https://doi.org/10.1175/jpo-d-21-0221.1 |
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ftunswworks:oai:unsworks.library.unsw.edu.au:1959.4/unsworks_81963 2024-06-02T07:57:12+00:00 The Origin and Fate of Antarctic Intermediate Water in the Southern Ocean Li, Z Groeskamp, S Cerovečki, I England, MH 2022-11-01 http://hdl.handle.net/1959.4/unsworks_81963 https://doi.org/10.1175/jpo-d-21-0221.1 unknown American Meteorological Society http://purl.org/au-research/grants/arc/SR200100008 http://hdl.handle.net/1959.4/unsworks_81963 https://doi.org/10.1175/jpo-d-21-0221.1 metadata only access http://purl.org/coar/access_right/c_14cb CC-BY https://creativecommons.org/licenses/by/4.0/ urn:ISSN:0022-3670 urn:ISSN:1520-0485 Journal of Physical Oceanography, 52, 11, 2873-2890 anzsrc-for: 0405 Oceanography anzsrc-for: 0911 Maritime Engineering journal article http://purl.org/coar/resource_type/c_6501 2022 ftunswworks https://doi.org/10.1175/jpo-d-21-0221.1 2024-05-07T23:45:23Z Using observationally based hydrographic and eddy diffusivity datasets, a volume budget analysis is per-formed to identify the main mechanisms governing the spatial and seasonal variability of Antarctic Intermediate Water (AAIW) within the density range γn = (27.25–27.7) kg m-3 in the Southern Ocean. The subduction rates and water mass transformation rates by mesoscale and small-scale turbulent mixing are estimated. First, Ekman pumping upwells the dense variety of AAIW into the mixed layer south of the Polar Front, which can be advected northward by Ekman transport into the subduction regions of lighter-variety AAIW and Subantarctic Mode Water (SAMW). The subduction of light AAIW occurs mainly by lateral advection in the southeast Pacific and Drake Passage as well as eddy-induced flow between the Subantarctic and Polar Fronts. The circumpolar-integrated total subduction yields from-5 to 19 Sv (1 Sv ≡ 106 m3 s-1) of AAIW volume loss. Second, the diapycnal transport from subducted SAMW into the AAIW layer is predominantly by mesoscale mixing (2–13 Sv) near the Subantarctic Front and vertical mixing in the South Pacific, while AAIW is further re-plenished by transformation from Upper Circumpolar Deep Water by vertical mixing (1–10 Sv). Last, 3–14 Sv of AAIW are exported out of the Southern Ocean. Our results suggest that the distribution of AAIW is set by its formation due to subduction and mixing, and its circulation eastward along the ACC and northward into the subtropical gyres. The volume budget analysis reveals strong seasonal variability in the rate of subduction, vertical mixing, and volume transport driving volume change within the AAIW layer. The nonzero volume budget residual suggests that more observations are needed to better constrain the estimate of geostrophic flow and mesoscale and small-scale mixing diffusivities. Article in Journal/Newspaper Antarc* Antarctic Drake Passage Southern Ocean UNSW Sydney (The University of New South Wales): UNSWorks Antarctic Southern Ocean Drake Passage Pacific Journal of Physical Oceanography 52 11 2873 2890 |
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Open Polar |
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UNSW Sydney (The University of New South Wales): UNSWorks |
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ftunswworks |
language |
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topic |
anzsrc-for: 0405 Oceanography anzsrc-for: 0911 Maritime Engineering |
spellingShingle |
anzsrc-for: 0405 Oceanography anzsrc-for: 0911 Maritime Engineering Li, Z Groeskamp, S Cerovečki, I England, MH The Origin and Fate of Antarctic Intermediate Water in the Southern Ocean |
topic_facet |
anzsrc-for: 0405 Oceanography anzsrc-for: 0911 Maritime Engineering |
description |
Using observationally based hydrographic and eddy diffusivity datasets, a volume budget analysis is per-formed to identify the main mechanisms governing the spatial and seasonal variability of Antarctic Intermediate Water (AAIW) within the density range γn = (27.25–27.7) kg m-3 in the Southern Ocean. The subduction rates and water mass transformation rates by mesoscale and small-scale turbulent mixing are estimated. First, Ekman pumping upwells the dense variety of AAIW into the mixed layer south of the Polar Front, which can be advected northward by Ekman transport into the subduction regions of lighter-variety AAIW and Subantarctic Mode Water (SAMW). The subduction of light AAIW occurs mainly by lateral advection in the southeast Pacific and Drake Passage as well as eddy-induced flow between the Subantarctic and Polar Fronts. The circumpolar-integrated total subduction yields from-5 to 19 Sv (1 Sv ≡ 106 m3 s-1) of AAIW volume loss. Second, the diapycnal transport from subducted SAMW into the AAIW layer is predominantly by mesoscale mixing (2–13 Sv) near the Subantarctic Front and vertical mixing in the South Pacific, while AAIW is further re-plenished by transformation from Upper Circumpolar Deep Water by vertical mixing (1–10 Sv). Last, 3–14 Sv of AAIW are exported out of the Southern Ocean. Our results suggest that the distribution of AAIW is set by its formation due to subduction and mixing, and its circulation eastward along the ACC and northward into the subtropical gyres. The volume budget analysis reveals strong seasonal variability in the rate of subduction, vertical mixing, and volume transport driving volume change within the AAIW layer. The nonzero volume budget residual suggests that more observations are needed to better constrain the estimate of geostrophic flow and mesoscale and small-scale mixing diffusivities. |
format |
Article in Journal/Newspaper |
author |
Li, Z Groeskamp, S Cerovečki, I England, MH |
author_facet |
Li, Z Groeskamp, S Cerovečki, I England, MH |
author_sort |
Li, Z |
title |
The Origin and Fate of Antarctic Intermediate Water in the Southern Ocean |
title_short |
The Origin and Fate of Antarctic Intermediate Water in the Southern Ocean |
title_full |
The Origin and Fate of Antarctic Intermediate Water in the Southern Ocean |
title_fullStr |
The Origin and Fate of Antarctic Intermediate Water in the Southern Ocean |
title_full_unstemmed |
The Origin and Fate of Antarctic Intermediate Water in the Southern Ocean |
title_sort |
origin and fate of antarctic intermediate water in the southern ocean |
publisher |
American Meteorological Society |
publishDate |
2022 |
url |
http://hdl.handle.net/1959.4/unsworks_81963 https://doi.org/10.1175/jpo-d-21-0221.1 |
geographic |
Antarctic Southern Ocean Drake Passage Pacific |
geographic_facet |
Antarctic Southern Ocean Drake Passage Pacific |
genre |
Antarc* Antarctic Drake Passage Southern Ocean |
genre_facet |
Antarc* Antarctic Drake Passage Southern Ocean |
op_source |
urn:ISSN:0022-3670 urn:ISSN:1520-0485 Journal of Physical Oceanography, 52, 11, 2873-2890 |
op_relation |
http://purl.org/au-research/grants/arc/SR200100008 http://hdl.handle.net/1959.4/unsworks_81963 https://doi.org/10.1175/jpo-d-21-0221.1 |
op_rights |
metadata only access http://purl.org/coar/access_right/c_14cb CC-BY https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1175/jpo-d-21-0221.1 |
container_title |
Journal of Physical Oceanography |
container_volume |
52 |
container_issue |
11 |
container_start_page |
2873 |
op_container_end_page |
2890 |
_version_ |
1800739780717182976 |