Articles | Volume 21, issue 4
https://doi.org/10.5194/os-21-1589-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-21-1589-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
30 Jul 2025
Research article |
| 30 Jul 2025
| 30 Jul 2025
Turbulent dissipation along contrasting internal tide paths off the Amazon shelf from AMAZOMIX
Fabius Kouogang
CORRESPONDING AUTHOR
CECI, Université de Toulouse, CERFACS/CNRS/IRD, Toulouse, France
Departamento de Oceanografia, Universidade Federal de Pernambuco, DOCEAN/UFPE, Recife, Brazil
Ariane Koch-Larrouy
CECI, Université de Toulouse, CERFACS/CNRS/IRD, Toulouse, France
Jorge Magalhaes
Department of Geoscience, Environment and Spatial Planning (DGAOT), Faculty of Sciences, University of Porto, Porto, Portugal
Alex Costa da Silva
Centro Euro-Mediterraneo sui Cambiamenti Climatici, Bologna, Italy
Daphne Kerhervé
CECI, Université de Toulouse, CERFACS/CNRS/IRD, Toulouse, France
Arnaud Bertrand
Departamento de Oceanografia, Universidade Federal de Pernambuco, DOCEAN/UFPE, Recife, Brazil
Evan Cervelli
Rockland Scientific Inc, Lunenburg, Nova Scotia, Canada
Fernand Assene
Centro Euro-Mediterraneo sui Cambiamenti Climatici, Bologna, Italy
Department of Maritime Navigation and Information Systems, National Advanced School of Maritime and Ocean Science and Technology (ENSTMO), University of Ebolowa, Ebolowa, Cameroon
Jean-François Ternon
MARBEC, Université de Montpellier, CNRS, Ifremer, IRD, Sète, France
Pierre Rousselot
IMAGO, Université de Bretagne Occidentale, CNRS, Ifremer, IRD, Brest, France
James Lee
Departamento de Oceanografia, Universidade Federal do Pará, UFPA, Belém, Brazil
Marcelo Rollnic
Departamento de Oceanografia, Universidade Federal do Pará, UFPA, Belém, Brazil
Moacyr Araujo
Departamento de Oceanografia, Universidade Federal de Pernambuco, DOCEAN/UFPE, Recife, Brazil
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Nicolas Metzl, Claire Lo Monaco, Aline Tribollet, Jean-François Ternon, Frédéric Chevallier, and Marion Gehlen
EGUsphere, https://doi.org/10.5194/egusphere-2025-3469, https://doi.org/10.5194/egusphere-2025-3469, 2025
This preprint is open for discussion and under review for Biogeosciences (BG).
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In the Mozambique Channel, observed acceleration of the ocean acidification in the recent decades is mainly driven by anthropogenic CO2 uptake. In this region the aragonite saturation state reached 3.2 in 2025 and could be as low as 3 in the next 10 years with potential impact on marine ecosystem including corals reefs areas.
Michel Tchilibou, Simon Barbot, Loren Carrere, Ariane Koch-Larrouy, Gérald Dibarboure, and Clément Ubelmann
Ocean Sci., 21, 1469–1486, https://doi.org/10.5194/os-21-1469-2025, https://doi.org/10.5194/os-21-1469-2025, 2025
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MIOST24 (Multivariate Inversion of Ocean Surface Topography 2024) annual and monthly internal tide (IT) atlases, based on 25 years of altimetry data and an updated wavelength database, are presented for the Indo-Philippine archipelago and the Amazon shelf. The atlases show monthly IT variability and a better correction of IT in altimetry data than with MIOST22 (MIOST 2022) and HRET (High-Resolution Empirical Tide). The results support the development of a global MIOST24.
Carina Regina de Macedo, Ariane Koch-Larrouy, José Carlos Bastos da Silva, Jorge Manuel Magalhães, Fernand Assene, Manh Duy Tran, Isabelle Dadou, Amine M’Hamdi, Trung Kien Tran, and Vincent Vantrepotte
EGUsphere, https://doi.org/10.5194/egusphere-2025-2307, https://doi.org/10.5194/egusphere-2025-2307, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
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We investigated how ocean tides influence marine phytoplankton along the North Brazilian coast. Using satellite data from 2005 to 2021, we found that tides can either enhance or reduce phytoplankton growth on the continental shelf. Offshore, internal tides stimulate primary production along their pathways. These results improve our understanding of how tidal processes shape marine life in tropical coastal regions.
Amine M'hamdi, Ariane Koch-Larrouy, Alex Costa da Silva, Isabelle Dadou, Carina Regina De Macedo, Anthony Bosse, Vincent Vantrepotte, Habib Micaël Aguedjou, Trung-Kien Tran, Pierre Testor, Laurent Mortier, Arnaud Bertrand, Pedro Augusto Mendes de Castro Melo, James Lee, Marcelo Rollnic, and Moacyr Araujo
EGUsphere, https://doi.org/10.5194/egusphere-2025-2141, https://doi.org/10.5194/egusphere-2025-2141, 2025
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In the ocean off the Amazon shelf, internal waves caused by tides shift water layers through advection and mix them through turbulence, altering the deep chlorophyll maximum, a proxy for phytoplankton. Using an autonomous underwater glider and satellite data, we found these waves redistribute chlorophyll vertically, enhancing its supply at the surface and at depth. This redistribution supports ocean productivity and may impact the entire marine food web.
Nicolas Metzl, Jonathan Fin, Claire Lo Monaco, Claude Mignon, Samir Alliouane, Bruno Bombled, Jacqueline Boutin, Yann Bozec, Steeve Comeau, Pascal Conan, Laurent Coppola, Pascale Cuet, Eva Ferreira, Jean-Pierre Gattuso, Frédéric Gazeau, Catherine Goyet, Emilie Grossteffan, Bruno Lansard, Dominique Lefèvre, Nathalie Lefèvre, Coraline Leseurre, Sébastien Petton, Mireille Pujo-Pay, Christophe Rabouille, Gilles Reverdin, Céline Ridame, Peggy Rimmelin-Maury, Jean-François Ternon, Franck Touratier, Aline Tribollet, Thibaut Wagener, and Cathy Wimart-Rousseau
Earth Syst. Sci. Data, 17, 1075–1100, https://doi.org/10.5194/essd-17-1075-2025, https://doi.org/10.5194/essd-17-1075-2025, 2025
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This work presents a new synthesis of 67 000 total alkalinity and total dissolved inorganic carbon observations obtained between 1993 and 2023 in the global ocean, coastal zones, and the Mediterranean Sea. We describe the data assemblage and associated quality control and discuss some potential uses of this dataset. The dataset is provided in a single format and includes the quality flag for each sample.
Fernand Assene, Ariane Koch-Larrouy, Isabelle Dadou, Michel Tchilibou, Guillaume Morvan, Jérôme Chanut, Alex Costa da Silva, Vincent Vantrepotte, Damien Allain, and Trung-Kien Tran
Ocean Sci., 20, 43–67, https://doi.org/10.5194/os-20-43-2024, https://doi.org/10.5194/os-20-43-2024, 2024
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Twin simulations, with and without tides, are used to assess the impact of internal tides (ITs) on ocean temperature off the Amazon mouth at a seasonal scale. We found that in the surface layers, ITs and barotropic tides cause a cooling effect on sea surface temperature, subsequently leading to an increase in the net heat flux between the atmosphere and ocean. Vertical mixing is identified as the primary driver, followed by vertical and horizontal advection.
Carina Regina de Macedo, Ariane Koch-Larrouy, José Carlos Bastos da Silva, Jorge Manuel Magalhães, Carlos Alessandre Domingos Lentini, Trung Kien Tran, Marcelo Caetano Barreto Rosa, and Vincent Vantrepotte
Ocean Sci., 19, 1357–1374, https://doi.org/10.5194/os-19-1357-2023, https://doi.org/10.5194/os-19-1357-2023, 2023
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We focus on the internal solitary waves (ISWs) off the Amazon shelf, their velocity, and their variability in seasonal and tidal cycles. The analysis is based on a large remote-sensing data set. The region is newly described as a hot spot for ISWs with mode-2 internal tide wavelength. The wave activity is higher during spring tides. The mode-1 waves located in the region influenced by the North Equatorial Counter Current showed a velocity/wavelength 14.3 % higher during the boreal summer/fall.
Djoirka Minto Dimoune, Florence Birol, Fabrice Hernandez, Fabien Léger, and Moacyr Araujo
Ocean Sci., 19, 251–268, https://doi.org/10.5194/os-19-251-2023, https://doi.org/10.5194/os-19-251-2023, 2023
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Altimeter-derived currents are used here to revisit the seasonal and interannual variability of all surface currents involved in the western tropical Atlantic circulation. A new approach based on the calculation of the current strengths and core positions is used to investigate the relationship between the currents, the remote wind variability, and the tropical Atlantic modes. The results show relationships at the seasonal and interannual timescale depending on the location of the currents.
Edward D. Zaron, Tonia A. Capuano, and Ariane Koch-Larrouy
Ocean Sci., 19, 43–55, https://doi.org/10.5194/os-19-43-2023, https://doi.org/10.5194/os-19-43-2023, 2023
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Phytoplankton in the upper ocean are food for fish and are thus economically important to humans; furthermore, phytoplankton consume nutrients and generate oxygen by photosynthesis, just like plants on land. Vertical mixing in the ocean is responsible for transporting nutrients into the sunlit zone of the surface ocean. We used remotely sensed data to quantify the influence of tidal mixing on phytoplankton through an analysis of ocean color, which we interpret as chlorophyll concentration.
Everton Giachini Tosetto, Arnaud Bertrand, Sigrid Neumann-Leitão, Alex Costa da Silva, and Miodeli Nogueira Júnior
Ocean Sci., 18, 1763–1779, https://doi.org/10.5194/os-18-1763-2022, https://doi.org/10.5194/os-18-1763-2022, 2022
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In the western tropical South Atlantic, coastward currents spread oceanic cnidarians over the continental shelf. While both coastal and oceanic communities co-occur in scenarios of higher runoff and weaker boundary current intensity, oceanic species dominate almost the entire shelf during the dry season characterized by stronger currents. Meanwhile, offshore, when the mixed-layer depth is shallower, the enhanced primary productivity supports larger populations of planktonic cnidarians.
Saúl Edgardo Martínez Castellón, José Henrique Cattanio, José Francisco Berrêdo, Marcelo Rollnic, Maria de Lourdes Ruivo, and Carlos Noriega
Biogeosciences, 19, 5483–5497, https://doi.org/10.5194/bg-19-5483-2022, https://doi.org/10.5194/bg-19-5483-2022, 2022
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We seek to understand the influence of climatic seasonality and microtopography on CO2 and CH4 fluxes in an Amazonian mangrove. Topography and seasonality had a contrasting influence when comparing the two gas fluxes: CO2 fluxes were greater in high topography in the dry period, and CH4 fluxes were greater in the rainy season in low topography. Only CO2 fluxes were correlated with soil organic matter, the proportion of carbon and nitrogen, and redox potential.
Michel Tchilibou, Ariane Koch-Larrouy, Simon Barbot, Florent Lyard, Yves Morel, Julien Jouanno, and Rosemary Morrow
Ocean Sci., 18, 1591–1618, https://doi.org/10.5194/os-18-1591-2022, https://doi.org/10.5194/os-18-1591-2022, 2022
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This high-resolution model-based study investigates the variability in the generation, propagation, and sea height signature (SSH) of the internal tide off the Amazon shelf during two contrasted seasons. ITs propagate further north during the season characterized by weak currents and mesoscale eddies and a shallow and strong pycnocline. IT imprints on SSH dominate those of the geostrophic motion for horizontal scales below 200 km; moreover, the SSH is mainly incoherent below 70 km.
Ramilla Vieira Assunção, Anne Lebourges-Dhaussy, Alex Costa da Silva, Bernard Bourlès, Gary Vargas, Gildas Roudaut, and Arnaud Bertrand
Ocean Sci. Discuss., https://doi.org/10.5194/os-2021-101, https://doi.org/10.5194/os-2021-101, 2021
Publication in OS not foreseen
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Active acoustics has been used to characterize physical structures and processes in the ocean, typically attributed to biological dispersion or turbulent structures. We take advantage of acoustic data from the Southwest Atlantic to test the feasibility of this approach in an oligotrophic region. The results show that the thermohaline structure impacts the vertical distribution of acoustic scatterers, however the methods tested did not allow a robust estimate of the thermohaline limits.
Josefine Herrford, Peter Brandt, Torsten Kanzow, Rebecca Hummels, Moacyr Araujo, and Jonathan V. Durgadoo
Ocean Sci., 17, 265–284, https://doi.org/10.5194/os-17-265-2021, https://doi.org/10.5194/os-17-265-2021, 2021
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The Atlantic Meridional Overturning Circulation (AMOC) is an important component of the climate system. Understanding its structure and variability is a key priority for many scientists. Here, we present the first estimate of AMOC variations for the tropical South Atlantic from the TRACOS array at 11° S. Over the observed period, the AMOC was dominated by seasonal variability. We investigate the respective mechanisms with an ocean model and find that different wind-forced waves play a big role.
Michel Tchilibou, Lionel Gourdeau, Florent Lyard, Rosemary Morrow, Ariane Koch Larrouy, Damien Allain, and Bughsin Djath
Ocean Sci., 16, 615–635, https://doi.org/10.5194/os-16-615-2020, https://doi.org/10.5194/os-16-615-2020, 2020
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This paper focuses on internal tides in the marginal Solomon Sea where LLWBCs transit. The objective is to characterize such internal tides and to give some insights into their impacts on water mass transformation in this area of interest for the global circulation. Results are discussed for two contrasted ENSO conditions with different mesoscale activity and stratification. Such study is motivated by the next altimetric SWOT mission that will be able to observe such phenomena.
Sandrine Djakouré, Moacyr Araujo, Aubains Hounsou-Gbo, Carlos Noriega, and Bernard Bourlès
Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-346, https://doi.org/10.5194/bg-2017-346, 2017
Revised manuscript has not been submitted
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Short summary
New research reveals that ocean mixing off the Amazon coast peaks not only near wave origins but also 230 km offshore, where different wave paths may intersect. This overlap likely forms strong solitary waves that intensify turbulence. Based on the AMAZOMIX-2021 cruise, which collected direct turbulence measurements alongside hydrographic data, the study quantifies dissipation and the relative contributions of tidal shear and large-scale shear. This mixing helps redistribute heat and nutrients, playing a key role in climate regulation and marine ecosystems.
New research reveals that ocean mixing off the Amazon coast peaks not only near wave origins but...
