Turbulent dissipation along contrasting internal tide paths off the Amazon shelf from AMAZOMIX
<p>The Amazon shelf break is a key oceanic region where strong internal tides (ITs) are generated, playing a substantial role in climate processes and ecosystems through vertical dissipation and mixing. During the AMAZOMIX survey (2021), currents, hydrography, and turbulence were measured over...
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Copernicus Publications
2025-07-01
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| Series: | Ocean Science |
| Online Access: | https://os.copernicus.org/articles/21/1589/2025/os-21-1589-2025.pdf |
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| author | F. Kouogang F. Kouogang A. Koch-Larrouy J. Magalhaes A. Costa da Silva D. Kerhervé A. Bertrand E. Cervelli F. Assene F. Assene J.-F. Ternon P. Rousselot J. Lee M. Rollnic M. Araujo |
| author_facet | F. Kouogang F. Kouogang A. Koch-Larrouy J. Magalhaes A. Costa da Silva D. Kerhervé A. Bertrand E. Cervelli F. Assene F. Assene J.-F. Ternon P. Rousselot J. Lee M. Rollnic M. Araujo |
| author_sort | F. Kouogang |
| collection | DOAJ |
| description | <p>The Amazon shelf break is a key oceanic region where strong internal tides (ITs) are generated, playing a substantial role in climate processes and ecosystems through vertical dissipation and mixing. During the AMAZOMIX survey (2021), currents, hydrography, and turbulence were measured over the M<span class="inline-formula"><sub>2</sub></span> tidal period (12.42 h) at multiple stations along both high (HTE) and low (LTE) tidal energy paths, covering IT generation and propagation regions off the Amazon shelf. This dataset provides a unique opportunity to assess IT-driven vertical dissipation and quantify its spatial extent and influence in the region.</p>
<p>Microstructure analyses, integrated with hydrographic data, highlighted contrasting dissipation rates. The highest rates occurred at IT generation sites along the HTE paths, while the lowest rates were observed on the slope along the LTE path. Near generation sites, the dissipation rates were elevated, [<span class="inline-formula">10<sup>−6</sup></span>] <span class="inline-formula">W kg<sup>−1</sup></span>, with IT shear contributing <span class="inline-formula">∼60</span> % compared to the mean baroclinic current (MBC) shear. Along IT paths, rates decreased to [<span class="inline-formula">10<sup>−8</sup></span>] <span class="inline-formula">W kg<sup>−1</sup></span> but remained substantial, driven by nearly equal contributions from IT and MBC shear.</p>
<p>A key finding was the relative increase in turbulent dissipation ([<span class="inline-formula">10<sup>−7</sup></span>] <span class="inline-formula">W kg<sup>−1</sup></span>) <span class="inline-formula">∼230</span> km from two distinct IT generation sites at the shelf break. This zone of high mixing was located in an area where the general circulation vanished, coinciding with a region of potential constructive interference of IT rays originating from different generation sites. It also aligned with the occurrence of large-amplitude internal solitary waves (ISWs), suggesting that constructive IT ray interference may generate nonlinear ISWs that lead to enhanced dissipation.</p> |
| format | Article |
| id | doaj-art-c0645bcdc74940f1806a3b6c5850c67b |
| institution | Matheson Library |
| issn | 1812-0784 1812-0792 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Copernicus Publications |
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| series | Ocean Science |
| spelling | doaj-art-c0645bcdc74940f1806a3b6c5850c67b2025-07-30T05:51:14ZengCopernicus PublicationsOcean Science1812-07841812-07922025-07-01211589160810.5194/os-21-1589-2025Turbulent dissipation along contrasting internal tide paths off the Amazon shelf from AMAZOMIXF. Kouogang0F. Kouogang1A. Koch-Larrouy2J. Magalhaes3A. Costa da Silva4D. Kerhervé5A. Bertrand6E. Cervelli7F. Assene8F. Assene9J.-F. Ternon10P. Rousselot11J. Lee12M. Rollnic13M. Araujo14CECI, Université de Toulouse, CERFACS/CNRS/IRD, Toulouse, FranceDepartamento de Oceanografia, Universidade Federal de Pernambuco, DOCEAN/UFPE, Recife, BrazilCECI, Université de Toulouse, CERFACS/CNRS/IRD, Toulouse, FranceDepartment of Geoscience, Environment and Spatial Planning (DGAOT), Faculty of Sciences, University of Porto, Porto, PortugalCentro Euro-Mediterraneo sui Cambiamenti Climatici, Bologna, ItalyCECI, Université de Toulouse, CERFACS/CNRS/IRD, Toulouse, FranceDepartamento de Oceanografia, Universidade Federal de Pernambuco, DOCEAN/UFPE, Recife, BrazilRockland Scientific Inc, Lunenburg, Nova Scotia, CanadaCentro Euro-Mediterraneo sui Cambiamenti Climatici, Bologna, ItalyDepartment of Maritime Navigation and Information Systems, National Advanced School of Maritime and Ocean Science and Technology (ENSTMO), University of Ebolowa, Ebolowa, CameroonMARBEC, Université de Montpellier, CNRS, Ifremer, IRD, Sète, FranceIMAGO, Université de Bretagne Occidentale, CNRS, Ifremer, IRD, Brest, FranceDepartamento de Oceanografia, Universidade Federal do Pará, UFPA, Belém, BrazilDepartamento de Oceanografia, Universidade Federal do Pará, UFPA, Belém, BrazilDepartamento de Oceanografia, Universidade Federal de Pernambuco, DOCEAN/UFPE, Recife, Brazil<p>The Amazon shelf break is a key oceanic region where strong internal tides (ITs) are generated, playing a substantial role in climate processes and ecosystems through vertical dissipation and mixing. During the AMAZOMIX survey (2021), currents, hydrography, and turbulence were measured over the M<span class="inline-formula"><sub>2</sub></span> tidal period (12.42 h) at multiple stations along both high (HTE) and low (LTE) tidal energy paths, covering IT generation and propagation regions off the Amazon shelf. This dataset provides a unique opportunity to assess IT-driven vertical dissipation and quantify its spatial extent and influence in the region.</p> <p>Microstructure analyses, integrated with hydrographic data, highlighted contrasting dissipation rates. The highest rates occurred at IT generation sites along the HTE paths, while the lowest rates were observed on the slope along the LTE path. Near generation sites, the dissipation rates were elevated, [<span class="inline-formula">10<sup>−6</sup></span>] <span class="inline-formula">W kg<sup>−1</sup></span>, with IT shear contributing <span class="inline-formula">∼60</span> % compared to the mean baroclinic current (MBC) shear. Along IT paths, rates decreased to [<span class="inline-formula">10<sup>−8</sup></span>] <span class="inline-formula">W kg<sup>−1</sup></span> but remained substantial, driven by nearly equal contributions from IT and MBC shear.</p> <p>A key finding was the relative increase in turbulent dissipation ([<span class="inline-formula">10<sup>−7</sup></span>] <span class="inline-formula">W kg<sup>−1</sup></span>) <span class="inline-formula">∼230</span> km from two distinct IT generation sites at the shelf break. This zone of high mixing was located in an area where the general circulation vanished, coinciding with a region of potential constructive interference of IT rays originating from different generation sites. It also aligned with the occurrence of large-amplitude internal solitary waves (ISWs), suggesting that constructive IT ray interference may generate nonlinear ISWs that lead to enhanced dissipation.</p>https://os.copernicus.org/articles/21/1589/2025/os-21-1589-2025.pdf |
| spellingShingle | F. Kouogang F. Kouogang A. Koch-Larrouy J. Magalhaes A. Costa da Silva D. Kerhervé A. Bertrand E. Cervelli F. Assene F. Assene J.-F. Ternon P. Rousselot J. Lee M. Rollnic M. Araujo Turbulent dissipation along contrasting internal tide paths off the Amazon shelf from AMAZOMIX Ocean Science |
| title | Turbulent dissipation along contrasting internal tide paths off the Amazon shelf from AMAZOMIX |
| title_full | Turbulent dissipation along contrasting internal tide paths off the Amazon shelf from AMAZOMIX |
| title_fullStr | Turbulent dissipation along contrasting internal tide paths off the Amazon shelf from AMAZOMIX |
| title_full_unstemmed | Turbulent dissipation along contrasting internal tide paths off the Amazon shelf from AMAZOMIX |
| title_short | Turbulent dissipation along contrasting internal tide paths off the Amazon shelf from AMAZOMIX |
| title_sort | turbulent dissipation along contrasting internal tide paths off the amazon shelf from amazomix |
| url | https://os.copernicus.org/articles/21/1589/2025/os-21-1589-2025.pdf |
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