On the Steadiness and Instability of the Intermediate Western Boundary Current between 24° and 18°S
The Intermediate Western Boundary Current (IWBC) transports Antarctic Intermediate Water across the Vitória-Trindade Ridge (VTR), a seamount chain at ∼20◦ S off Brazil. Recent studies suggest that the IWBC develops a strong cyclonic recirculation in Tubarão Bight, upstream of the VTR, with weak time...
| Main Authors: | , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
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American Meteorological Society
2020
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| Online Access: | https://hdl.handle.net/1721.1/124953 |
| _version_ | 1811069212637003776 |
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| author | Napolitano, Dante C. da Silveira, Ilson C. A. Rocha, Cesar B. Flierl, Glenn Richard Calil, Paulo H R. Martins, Renato P. |
| author2 | Woods Hole Oceanographic Institution |
| author_facet | Woods Hole Oceanographic Institution Napolitano, Dante C. da Silveira, Ilson C. A. Rocha, Cesar B. Flierl, Glenn Richard Calil, Paulo H R. Martins, Renato P. |
| author_sort | Napolitano, Dante C. |
| collection | MIT |
| description | The Intermediate Western Boundary Current (IWBC) transports Antarctic Intermediate Water across the Vitória-Trindade Ridge (VTR), a seamount chain at ∼20◦ S off Brazil. Recent studies suggest that the IWBC develops a strong cyclonic recirculation in Tubarão Bight, upstream of the VTR, with weak time dependency. We herein use new quasi-synoptic observations, data from the Argo array, and a regional numerical model to describe structure and variablity of the IWBC, and to investigate its dynamics. Both shipboard-ADCP data and trajectories of Argo floats confirm the existence of the IWBC recirculation, which is also captured by our ROMS simulation. An “intermediate-layer” quasi-geostrophic (QG) model indicates that the ROMS time-mean flow is a good proxy for the IWBC steady state, as revealed by largely parallel isolines of streamfunction (¯ψ) and potential vorticity (¯Q); a ¯ψ-¯Q scatter diagram also shows that the IWBC is potentially unstable. Further analysis of the ROMS simulation reveals that remotely-generated, westward-propagating nonlinear eddies are the main source of variability in the region. These eddies enter the domain through the Tubarão Bight eastern edge and strongly interact with the IWBC. As they are advected downstream and negotiate the local topography, the eddies grow explosively through horizontal shear production. ©2019 American Meteorological Society. |
| first_indexed | 2024-09-23T08:07:30Z |
| format | Article |
| id | mit-1721.1/124953 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T08:07:30Z |
| publishDate | 2020 |
| publisher | American Meteorological Society |
| record_format | dspace |
| spelling | mit-1721.1/1249532022-09-23T11:03:00Z On the Steadiness and Instability of the Intermediate Western Boundary Current between 24° and 18°S Napolitano, Dante C. da Silveira, Ilson C. A. Rocha, Cesar B. Flierl, Glenn Richard Calil, Paulo H R. Martins, Renato P. Woods Hole Oceanographic Institution Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences The Intermediate Western Boundary Current (IWBC) transports Antarctic Intermediate Water across the Vitória-Trindade Ridge (VTR), a seamount chain at ∼20◦ S off Brazil. Recent studies suggest that the IWBC develops a strong cyclonic recirculation in Tubarão Bight, upstream of the VTR, with weak time dependency. We herein use new quasi-synoptic observations, data from the Argo array, and a regional numerical model to describe structure and variablity of the IWBC, and to investigate its dynamics. Both shipboard-ADCP data and trajectories of Argo floats confirm the existence of the IWBC recirculation, which is also captured by our ROMS simulation. An “intermediate-layer” quasi-geostrophic (QG) model indicates that the ROMS time-mean flow is a good proxy for the IWBC steady state, as revealed by largely parallel isolines of streamfunction (¯ψ) and potential vorticity (¯Q); a ¯ψ-¯Q scatter diagram also shows that the IWBC is potentially unstable. Further analysis of the ROMS simulation reveals that remotely-generated, westward-propagating nonlinear eddies are the main source of variability in the region. These eddies enter the domain through the Tubarão Bight eastern edge and strongly interact with the IWBC. As they are advected downstream and negotiate the local topography, the eddies grow explosively through horizontal shear production. ©2019 American Meteorological Society. Projeto REMARSUL (Processo CAPES 88882.158621/2014-01) Projeto VT-Dyn (Processo FAPESP 2015/21729-4) Projeto SUBMESO (Processo CNPq 442926/2015-4) WHOI Postdoctoral Scholarship 2020-04-30T19:36:42Z 2020-04-30T19:36:42Z 2019-12 2019-01 2020-04-08T18:37:37Z Article http://purl.org/eprint/type/JournalArticle 1520-0485 https://hdl.handle.net/1721.1/124953 Napolitano, Dante C. et. al., "On the Steadiness and Instability of the Intermediate Western Boundary Current between 24° and 18°S." Journal of Physical Oceanography 49, 12 (December 2019): 3127-43 doi. 10.1175/JPO-D-19-0011.1 ©2019 Authors en 10.1175/JPO-D-19-0011.1 Journal of Physical Oceanography Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Meteorological Society American Meteorological Society |
| spellingShingle | Napolitano, Dante C. da Silveira, Ilson C. A. Rocha, Cesar B. Flierl, Glenn Richard Calil, Paulo H R. Martins, Renato P. On the Steadiness and Instability of the Intermediate Western Boundary Current between 24° and 18°S |
| title | On the Steadiness and Instability of the Intermediate Western Boundary Current between 24° and 18°S |
| title_full | On the Steadiness and Instability of the Intermediate Western Boundary Current between 24° and 18°S |
| title_fullStr | On the Steadiness and Instability of the Intermediate Western Boundary Current between 24° and 18°S |
| title_full_unstemmed | On the Steadiness and Instability of the Intermediate Western Boundary Current between 24° and 18°S |
| title_short | On the Steadiness and Instability of the Intermediate Western Boundary Current between 24° and 18°S |
| title_sort | on the steadiness and instability of the intermediate western boundary current between 24° and 18°s |
| url | https://hdl.handle.net/1721.1/124953 |
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