Unique current connecting Southern and Indian Oceans identified from radium distributions
Abstract We examined the spatial variations in 226Ra and 228Ra (activities) concentrations from the surface to a depth of 830 m in the Indian and Southern Oceans from December 2019 to January 2020. 226Ra concentrations at the surface increased sharply from 30° S to 60° S along a ~ 55° E transect (1....
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2022-02-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-022-05928-y |
| _version_ | 1818500902891290624 |
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| author | Mutsuo Inoue Shotaro Hanaki Hiroaki Kameyama Yuichiro Kumamoto Seiya Nagao |
| author_facet | Mutsuo Inoue Shotaro Hanaki Hiroaki Kameyama Yuichiro Kumamoto Seiya Nagao |
| author_sort | Mutsuo Inoue |
| collection | DOAJ |
| description | Abstract We examined the spatial variations in 226Ra and 228Ra (activities) concentrations from the surface to a depth of 830 m in the Indian and Southern Oceans from December 2019 to January 2020. 226Ra concentrations at the surface increased sharply from 30° S to 60° S along a ~ 55° E transect (1.4–2.9 mBq/L), exhibiting small vertical variations, while 228Ra decreased southward and became depleted in the Southern Ocean. These distributions indicated the ocean-scale northward lateral transport of 226Ra-rich and 228Ra-depleted currents originating from the Antarctic Circumpolar Current (ACC). 226Ra concentrations indicated that the fractions of the ACC at depths of 0–800 m decreased from 0.95 to 0.14 between 60° S and 30° S. The ACC fractions in the subantarctic western Indian Ocean were higher than those previously reported in the eastern Indian region, indicating preferential transport of the ACC. The fractions obtained were approximately equivalent to those in the western Indian Ocean in the 1970s. This could be attributed to the minimal southward shift of the polar front due to global warming over the last 50 years. |
| first_indexed | 2024-12-10T20:48:57Z |
| format | Article |
| id | doaj.art-21d856ed92604a5c8ce7006c0f6c1f70 |
| institution | Directory Open Access Journal |
| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-12-10T20:48:57Z |
| publishDate | 2022-02-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj.art-21d856ed92604a5c8ce7006c0f6c1f702022-12-22T01:34:10ZengNature PortfolioScientific Reports2045-23222022-02-0112111110.1038/s41598-022-05928-yUnique current connecting Southern and Indian Oceans identified from radium distributionsMutsuo Inoue0Shotaro Hanaki1Hiroaki Kameyama2Yuichiro Kumamoto3Seiya Nagao4Low Level Radioactivity Laboratory, Kanazawa UniversityLow Level Radioactivity Laboratory, Kanazawa UniversityLow Level Radioactivity Laboratory, Kanazawa UniversityResearch and Development Center for Global Change, Japan Agency for Marine-Earth Science and TechnologyLow Level Radioactivity Laboratory, Kanazawa UniversityAbstract We examined the spatial variations in 226Ra and 228Ra (activities) concentrations from the surface to a depth of 830 m in the Indian and Southern Oceans from December 2019 to January 2020. 226Ra concentrations at the surface increased sharply from 30° S to 60° S along a ~ 55° E transect (1.4–2.9 mBq/L), exhibiting small vertical variations, while 228Ra decreased southward and became depleted in the Southern Ocean. These distributions indicated the ocean-scale northward lateral transport of 226Ra-rich and 228Ra-depleted currents originating from the Antarctic Circumpolar Current (ACC). 226Ra concentrations indicated that the fractions of the ACC at depths of 0–800 m decreased from 0.95 to 0.14 between 60° S and 30° S. The ACC fractions in the subantarctic western Indian Ocean were higher than those previously reported in the eastern Indian region, indicating preferential transport of the ACC. The fractions obtained were approximately equivalent to those in the western Indian Ocean in the 1970s. This could be attributed to the minimal southward shift of the polar front due to global warming over the last 50 years.https://doi.org/10.1038/s41598-022-05928-y |
| spellingShingle | Mutsuo Inoue Shotaro Hanaki Hiroaki Kameyama Yuichiro Kumamoto Seiya Nagao Unique current connecting Southern and Indian Oceans identified from radium distributions Scientific Reports |
| title | Unique current connecting Southern and Indian Oceans identified from radium distributions |
| title_full | Unique current connecting Southern and Indian Oceans identified from radium distributions |
| title_fullStr | Unique current connecting Southern and Indian Oceans identified from radium distributions |
| title_full_unstemmed | Unique current connecting Southern and Indian Oceans identified from radium distributions |
| title_short | Unique current connecting Southern and Indian Oceans identified from radium distributions |
| title_sort | unique current connecting southern and indian oceans identified from radium distributions |
| url | https://doi.org/10.1038/s41598-022-05928-y |
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