Tracking the spread of a passive tracer through Southern Ocean water masses
A dynamically passive inert tracer was released in the interior South Pacific Ocean at latitudes of the Antarctic Circumpolar Current. Observational cross sections of the tracer were taken over 4 consecutive years as it drifted through Drake Passage and into the Atlantic Ocean. The tracer was releas...
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ftcopernicus:oai:publications.copernicus.org:os79740 2023-05-15T13:55:28+02:00 Tracking the spread of a passive tracer through Southern Ocean water masses Zika, Jan D. Sallée, Jean-Baptiste Meijers, Andrew J. S. Naveira-Garabato, Alberto C. Watson, Andrew J. Messias, Marie-Jose King, Brian A. 2020-03-12 application/pdf https://doi.org/10.5194/os-16-323-2020 https://os.copernicus.org/articles/16/323/2020/ eng eng doi:10.5194/os-16-323-2020 https://os.copernicus.org/articles/16/323/2020/ eISSN: 1812-0792 Text 2020 ftcopernicus https://doi.org/10.5194/os-16-323-2020 2020-07-20T16:22:21Z A dynamically passive inert tracer was released in the interior South Pacific Ocean at latitudes of the Antarctic Circumpolar Current. Observational cross sections of the tracer were taken over 4 consecutive years as it drifted through Drake Passage and into the Atlantic Ocean. The tracer was released within a region of high salinity relative to surrounding waters at the same density. In the absence of irreversible mixing a tracer remains at constant salinity and temperature on an isopycnal surface. To investigate the process of irreversible mixing we analysed the tracer in potential density-versus-salinity-anomaly coordinates. Observations of high tracer concentration tended to be collocated with isopycnal salinity anomalies. With time, an initially narrow peak in tracer concentration as a function of salinity at constant density broadened with the tracer being found at ever fresher salinities, consistent with diffusion-like behaviour in that coordinate system. The second moment of the tracer as a function of salinity suggested an initial period of slow spreading for approximately 2 years in the Pacific, followed by more rapid spreading as the tracer entered Drake Passage and the Scotia Sea. Analysis of isopycnal salinity gradients based on the Argo programme suggests that part of this apparent change can be explained by changes in background salinity gradients while part may be explained by the evolution of the tracer patch from a slowly growing phase where the tracer forms filaments to a more rapid phase where the tracer mixes at 240–550 m 2 s −1 . Text Antarc* Antarctic Drake Passage Scotia Sea Southern Ocean Copernicus Publications: E-Journals Antarctic Drake Passage Pacific Scotia Sea Southern Ocean The Antarctic Ocean Science 16 2 323 336 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
A dynamically passive inert tracer was released in the interior South Pacific Ocean at latitudes of the Antarctic Circumpolar Current. Observational cross sections of the tracer were taken over 4 consecutive years as it drifted through Drake Passage and into the Atlantic Ocean. The tracer was released within a region of high salinity relative to surrounding waters at the same density. In the absence of irreversible mixing a tracer remains at constant salinity and temperature on an isopycnal surface. To investigate the process of irreversible mixing we analysed the tracer in potential density-versus-salinity-anomaly coordinates. Observations of high tracer concentration tended to be collocated with isopycnal salinity anomalies. With time, an initially narrow peak in tracer concentration as a function of salinity at constant density broadened with the tracer being found at ever fresher salinities, consistent with diffusion-like behaviour in that coordinate system. The second moment of the tracer as a function of salinity suggested an initial period of slow spreading for approximately 2 years in the Pacific, followed by more rapid spreading as the tracer entered Drake Passage and the Scotia Sea. Analysis of isopycnal salinity gradients based on the Argo programme suggests that part of this apparent change can be explained by changes in background salinity gradients while part may be explained by the evolution of the tracer patch from a slowly growing phase where the tracer forms filaments to a more rapid phase where the tracer mixes at 240–550 m 2 s −1 . |
format |
Text |
author |
Zika, Jan D. Sallée, Jean-Baptiste Meijers, Andrew J. S. Naveira-Garabato, Alberto C. Watson, Andrew J. Messias, Marie-Jose King, Brian A. |
spellingShingle |
Zika, Jan D. Sallée, Jean-Baptiste Meijers, Andrew J. S. Naveira-Garabato, Alberto C. Watson, Andrew J. Messias, Marie-Jose King, Brian A. Tracking the spread of a passive tracer through Southern Ocean water masses |
author_facet |
Zika, Jan D. Sallée, Jean-Baptiste Meijers, Andrew J. S. Naveira-Garabato, Alberto C. Watson, Andrew J. Messias, Marie-Jose King, Brian A. |
author_sort |
Zika, Jan D. |
title |
Tracking the spread of a passive tracer through Southern Ocean water masses |
title_short |
Tracking the spread of a passive tracer through Southern Ocean water masses |
title_full |
Tracking the spread of a passive tracer through Southern Ocean water masses |
title_fullStr |
Tracking the spread of a passive tracer through Southern Ocean water masses |
title_full_unstemmed |
Tracking the spread of a passive tracer through Southern Ocean water masses |
title_sort |
tracking the spread of a passive tracer through southern ocean water masses |
publishDate |
2020 |
url |
https://doi.org/10.5194/os-16-323-2020 https://os.copernicus.org/articles/16/323/2020/ |
geographic |
Antarctic Drake Passage Pacific Scotia Sea Southern Ocean The Antarctic |
geographic_facet |
Antarctic Drake Passage Pacific Scotia Sea Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Drake Passage Scotia Sea Southern Ocean |
genre_facet |
Antarc* Antarctic Drake Passage Scotia Sea Southern Ocean |
op_source |
eISSN: 1812-0792 |
op_relation |
doi:10.5194/os-16-323-2020 https://os.copernicus.org/articles/16/323/2020/ |
op_doi |
https://doi.org/10.5194/os-16-323-2020 |
container_title |
Ocean Science |
container_volume |
16 |
container_issue |
2 |
container_start_page |
323 |
op_container_end_page |
336 |
_version_ |
1766262095053062144 |