Articles | Volume 21, issue 1
https://doi.org/10.5194/os-21-325-2025
© 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-21-325-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| Highlight paper
| 
04 Feb 2025
Research article | Highlight paper |
| 04 Feb 2025
| 04 Feb 2025
Internal tides off the Amazon shelf in the western tropical Atlantic: analysis of SWOT Cal/Val mission data
Michel Tchilibou
CORRESPONDING AUTHOR
Collecte Localisation Satellites (CLS), 31520 Ramonville-Saint-Agne, France
Loren Carrere
Collecte Localisation Satellites (CLS), 31520 Ramonville-Saint-Agne, France
Florent Lyard
Université de Toulouse, LEGOS (CNES/CNRS/IRD/UT3), 31400 Toulouse, France
Clément Ubelmann
Datlas, Grenoble, France
Gérald Dibarboure
Centre National d'Etude Spatiales, 31400 Toulouse, France
Edward D. Zaron
College of Earth, Ocean and Atmospheric Science, Oregon State University, Corvallis, OR, USA
Brian K. Arbic
Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
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This study presents the annual and monthly MIOST (MIOST24) internal tide atlases for the Indo-Philippine archipelago and the region off the Amazon shelf. Derived from 25 years of altimetry data and an updated wavelength database, the atlases reveal significant monthly variability of internal tides in both regions. The new atlas improves the correction of internal tides in altimetry data and outperforms MIOST 2022 and HRET existing atlases, thus supporting the development of a global atlas.
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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.
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New Caledonia is a hot spot of internal-tide generation due to complex bathymetry. Regional modeling quantifies the coherent internal tide and shows that most energy is converted in shallow waters and on very steep slopes. The region is a challenge for observability of balanced dynamics due to strong internal-tide sea surface height (SSH) signatures at similar wavelengths. Correcting the SSH for the coherent internal tide may increase the observability of balanced motion to < 100 km.
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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.
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Internal tides are responsible for surface deformations of the ocean that could affect the measurements of the forthcoming SWOT altimetric mission and need to be corrected. This study highlights the variability of the properties of internal tides based on the stratification variability only. A single methodology is successfully applied in two areas driven by different oceanic processes: the western equatorial Atlantic and the Bay of Biscay.
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Temporal variability of the semidiurnal internal tide around New Caledonia is investigated using regional modeling. An important contribution to temporal variability not linked to the astronomically-forced spring-neap cycle is due to the presence of mesoscale eddies, both at the generation sites and in propagation direction. The incoherent tide has a widespread signature in sea surface height (SSH) challenging the SSH observability of mesoscale to submesoscale dynamics.
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The Surface Water and Ocean Topography (SWOT) mission provides unprecedented swath altimetry data. This study examines SWOT's impact on mapping systems, showing a moderate effect with the current nadir altimetry constellation and a stronger impact with a reduced one. Integrating SWOT with dynamic mapping techniques improves the resolution of satellite-derived products, offering promising solutions for studying and monitoring sea-level variability at finer scales.
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This study presents the annual and monthly MIOST (MIOST24) internal tide atlases for the Indo-Philippine archipelago and the region off the Amazon shelf. Derived from 25 years of altimetry data and an updated wavelength database, the atlases reveal significant monthly variability of internal tides in both regions. The new atlas improves the correction of internal tides in altimetry data and outperforms MIOST 2022 and HRET existing atlases, thus supporting the development of a global atlas.
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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.
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Ocean Sci., 19, 1315–1338, https://doi.org/10.5194/os-19-1315-2023, https://doi.org/10.5194/os-19-1315-2023, 2023
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New Caledonia is a hot spot of internal-tide generation due to complex bathymetry. Regional modeling quantifies the coherent internal tide and shows that most energy is converted in shallow waters and on very steep slopes. The region is a challenge for observability of balanced dynamics due to strong internal-tide sea surface height (SSH) signatures at similar wavelengths. Correcting the SSH for the coherent internal tide may increase the observability of balanced motion to < 100 km.
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Ocean Sci., 19, 811–835, https://doi.org/10.5194/os-19-811-2023, https://doi.org/10.5194/os-19-811-2023, 2023
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The ocean state is sensitive to the mixing originating from internal tides (ITs). To date, our knowledge of the magnitude and spatial distribution of this mixing mostly relies on uncertain modeling. Here, we use novel observations from autonomous floats to validate the spatial variability in the semidiurnal IT in a realistic ocean simulation. The numerical simulation is found to correctly reproduce the main spatial patterns of the observed tidal energy but to be biased low at the global scale.
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Nairita Pal, Kristin N. Barton, Mark R. Petersen, Steven R. Brus, Darren Engwirda, Brian K. Arbic, Andrew F. Roberts, Joannes J. Westerink, and Damrongsak Wirasaet
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Understanding tides is essential to accurately predict ocean currents. Over the next several decades coastal processes such as flooding and erosion will be severely impacted due to climate change. Tides affect currents along the coastal regions the most. In this paper we show the results of implementing tides in a global ocean model known as MPAS–Ocean. We also show how Antarctic ice shelf cavities affect global tides. Our work points towards future research with tide–ice interactions.
Maxime Ballarotta, Clément Ubelmann, Pierre Veillard, Pierre Prandi, Hélène Etienne, Sandrine Mulet, Yannice Faugère, Gérald Dibarboure, Rosemary Morrow, and Nicolas Picot
Earth Syst. Sci. Data, 15, 295–315, https://doi.org/10.5194/essd-15-295-2023, https://doi.org/10.5194/essd-15-295-2023, 2023
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We present a new gridded sea surface height and current dataset produced by combining observations from nadir altimeters and drifting buoys. This product is based on a multiscale and multivariate mapping approach that offers the possibility to improve the physical content of gridded products by combining the data from various platforms and resolving a broader spectrum of ocean surface dynamic than in the current operational mapping system. A quality assessment of this new product is presented.
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
Short summary
Short summary
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.
Marie-Isabelle Pujol, Stéphanie Dupuy, Oscar Vergara, Antonio Sánchez-Román, Yannice Faugère, Pierre Prandi, Mei-Ling Dabat, Quentin Dagneaux, Marine Lievin, Emeline Cadier, Gérald Dibarboure, and Nicolas Picot
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2022-292, https://doi.org/10.5194/essd-2022-292, 2022
Manuscript not accepted for further review
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An altimeter sea level along-track level-3 product with a 5 Hz (~1.2 km) sampling is proposed. It takes advantage of recent advances in radar altimeter processing, and improvements made to different stages of the processing chain. Compared to the conventional 1 Hz (~7 km) product, it significantly improves the observability of the short wavelength signal in open ocean and near coast areas (> 5 km). It also contributes to improving high resolution numerical model outputs via data assimilation.
Takaya Uchida, Julien Le Sommer, Charles Stern, Ryan P. Abernathey, Chris Holdgraf, Aurélie Albert, Laurent Brodeau, Eric P. Chassignet, Xiaobiao Xu, Jonathan Gula, Guillaume Roullet, Nikolay Koldunov, Sergey Danilov, Qiang Wang, Dimitris Menemenlis, Clément Bricaud, Brian K. Arbic, Jay F. Shriver, Fangli Qiao, Bin Xiao, Arne Biastoch, René Schubert, Baylor Fox-Kemper, William K. Dewar, and Alan Wallcraft
Geosci. Model Dev., 15, 5829–5856, https://doi.org/10.5194/gmd-15-5829-2022, https://doi.org/10.5194/gmd-15-5829-2022, 2022
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Ocean and climate scientists have used numerical simulations as a tool to examine the ocean and climate system since the 1970s. Since then, owing to the continuous increase in computational power and advances in numerical methods, we have been able to simulate increasing complex phenomena. However, the fidelity of the simulations in representing the phenomena remains a core issue in the ocean science community. Here we propose a cloud-based framework to inter-compare and assess such simulations.
Mounir Benkiran, Pierre-Yves Le Traon, and Gérald Dibarboure
Ocean Sci., 18, 609–625, https://doi.org/10.5194/os-18-609-2022, https://doi.org/10.5194/os-18-609-2022, 2022
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The SSH analysis and 7 d forecast error will be globally reduced by almost 50 %. Surface current forecast errors should be equivalent to today’s surface current analysis errors or alternatively will be improved (variance error reduction) by 30 % at the surface and 50 % for 300 m depth.
The resolution capabilities will be drastically improved and will be closer to 100 km wavelength as opposed to today where they are above 250 km (on average).
Clément Ubelmann, Loren Carrere, Chloé Durand, Gérald Dibarboure, Yannice Faugère, Maxime Ballarotta, Frédéric Briol, and Florent Lyard
Ocean Sci., 18, 469–481, https://doi.org/10.5194/os-18-469-2022, https://doi.org/10.5194/os-18-469-2022, 2022
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The signature of internal tides has become an important component for high-resolution altimetry over oceans. Several studies have proposed some solutions to resolve part of these internal tides based on the altimetry record. Following these studies, we propose here a new inversion approach aimed to mitigate aliasing with other dynamics. After a description of the methodology, the solution for the main tidal components has been successfully validated against independent observations.
Cori Pegliasco, Antoine Delepoulle, Evan Mason, Rosemary Morrow, Yannice Faugère, and Gérald Dibarboure
Earth Syst. Sci. Data, 14, 1087–1107, https://doi.org/10.5194/essd-14-1087-2022, https://doi.org/10.5194/essd-14-1087-2022, 2022
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The new global Mesoscale Eddy Trajectory Atlases (META3.1exp) provide eddy identification and trajectories from altimetry maps. These atlases comprise an improvement to and continuation of the historical META2.0 product. Changes in the detection parameters and tracking were tested by comparing the eddies from the different datasets. In particular, the eddy contours available in META3.1exp are an asset for multi-disciplinary studies.
Pierre Prandi, Jean-Christophe Poisson, Yannice Faugère, Amandine Guillot, and Gérald Dibarboure
Earth Syst. Sci. Data, 13, 5469–5482, https://doi.org/10.5194/essd-13-5469-2021, https://doi.org/10.5194/essd-13-5469-2021, 2021
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We investigate how mapping sea level in the Arctic Ocean can benefit from combining data from three satellite radar altimeters: CryoSat-2, Sentinel-3A and SARAL/AltiKa. A dedicated processing for SARAL/AltiKa provides a baseline for the cross-referencing of CryoSat-2 and Sentinel-3A before mapping. We show that by combining measurements coming from three missions, we are able to increase the resolution of gridded sea level fields in the ice-covered Arctic Ocean.
Simon Barbot, Florent Lyard, Michel Tchilibou, and Loren Carrere
Ocean Sci., 17, 1563–1583, https://doi.org/10.5194/os-17-1563-2021, https://doi.org/10.5194/os-17-1563-2021, 2021
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Internal tides are responsible for surface deformations of the ocean that could affect the measurements of the forthcoming SWOT altimetric mission and need to be corrected. This study highlights the variability of the properties of internal tides based on the stratification variability only. A single methodology is successfully applied in two areas driven by different oceanic processes: the western equatorial Atlantic and the Bay of Biscay.
Sandrine Mulet, Marie-Hélène Rio, Hélène Etienne, Camilia Artana, Mathilde Cancet, Gérald Dibarboure, Hui Feng, Romain Husson, Nicolas Picot, Christine Provost, and P. Ted Strub
Ocean Sci., 17, 789–808, https://doi.org/10.5194/os-17-789-2021, https://doi.org/10.5194/os-17-789-2021, 2021
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Satellite altimetry has revolutionized ocean observation by allowing the sea level to be monitored with very good spatiotemporal coverage. However, only the sea level anomalies are retrieved; to monitor the whole oceanic signal a temporal mean (called mean dynamic topography, MDT) must be added to these anomalies. In this study we present the newly updated CNES-CLS18 MDT. An evaluation of this new solution shows significant improvements in both strong currents and coastal areas.
Florent H. Lyard, Damien J. Allain, Mathilde Cancet, Loren Carrère, and Nicolas Picot
Ocean Sci., 17, 615–649, https://doi.org/10.5194/os-17-615-2021, https://doi.org/10.5194/os-17-615-2021, 2021
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Since the mid-1990s, a series of FES (finite element solution) global ocean tidal atlases has been produced with the primary objective to provide altimetry missions with a tidal de-aliasing correction. We describe the underlying hydrodynamic/data assimilation design and accuracy assessments for the FES2014 release. The FES2014 atlas shows overall improved performance and has consequently been integrated in satellite altimetry and gravimetric data processing and adopted in ITRF standards.
Loren Carrere, Brian K. Arbic, Brian Dushaw, Gary Egbert, Svetlana Erofeeva, Florent Lyard, Richard D. Ray, Clément Ubelmann, Edward Zaron, Zhongxiang Zhao, Jay F. Shriver, Maarten Cornelis Buijsman, and Nicolas Picot
Ocean Sci., 17, 147–180, https://doi.org/10.5194/os-17-147-2021, https://doi.org/10.5194/os-17-147-2021, 2021
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Internal tides can have a signature of several centimeters at the ocean surface and need to be corrected from altimeter measurements. We present a detailed validation of several internal-tide models using existing satellite altimeter databases. The analysis focuses on the main diurnal and semidiurnal tidal constituents. Results show the interest of the methodology proposed, the quality of the internal-tide models tested and their positive contribution for estimating an accurate sea level.
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.
Guillaume Taburet, Antonio Sanchez-Roman, Maxime Ballarotta, Marie-Isabelle Pujol, Jean-François Legeais, Florent Fournier, Yannice Faugere, and Gerald Dibarboure
Ocean Sci., 15, 1207–1224, https://doi.org/10.5194/os-15-1207-2019, https://doi.org/10.5194/os-15-1207-2019, 2019
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This paper deals with sea level altimetery products. These geophysical data are distributed as along-track and gridded data through Copernicus programs CMEMS and C3S. We present in detail a new reprocessing of the data (DT2018) from 1993 to 2017. The main changes and their impacts since the last version (DT2014) are carefully discussed. This comparison is made using an independent dataset. DT2018 sea level products are improved at the global and regional scale, especially in coastal areas.
Maxime Ballarotta, Clément Ubelmann, Marie-Isabelle Pujol, Guillaume Taburet, Florent Fournier, Jean-François Legeais, Yannice Faugère, Antoine Delepoulle, Dudley Chelton, Gérald Dibarboure, and Nicolas Picot
Ocean Sci., 15, 1091–1109, https://doi.org/10.5194/os-15-1091-2019, https://doi.org/10.5194/os-15-1091-2019, 2019
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This study investigates the resolving capabilities of the DUACS gridded products delivered through the CMEMS catalogue. Our method is based on the noise-to-signal ratio approach. While altimeter along-track data resolve scales on the order of a few tens of kilometers, we found that the merging of these along-track data into continuous maps in time and space leads to effective resolution ranging from ~ 800 km wavelength at the Equator to 100 km wavelength at high latitude.
Michel Tchilibou, Lionel Gourdeau, Rosemary Morrow, Guillaume Serazin, Bughsin Djath, and Florent Lyard
Ocean Sci., 14, 1283–1301, https://doi.org/10.5194/os-14-1283-2018, https://doi.org/10.5194/os-14-1283-2018, 2018
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This paper is motivated by the next SWOT altimetric mission dedicated to the observation of mesoscale and submesoscale oceanic features. It focuses on tropical areas with a strong discrepancy in the spectral signature between altimetry and models. The paper reviews the spectral signature of tropical turbulence which presents a rich variety of phenomena depending on the latitudinal dependence of the Coriolis force. Internal tides observed by altimetry explain the discrepancy with the model.
Fabrice Ardhuin, Yevgueny Aksenov, Alvise Benetazzo, Laurent Bertino, Peter Brandt, Eric Caubet, Bertrand Chapron, Fabrice Collard, Sophie Cravatte, Jean-Marc Delouis, Frederic Dias, Gérald Dibarboure, Lucile Gaultier, Johnny Johannessen, Anton Korosov, Georgy Manucharyan, Dimitris Menemenlis, Melisa Menendez, Goulven Monnier, Alexis Mouche, Frédéric Nouguier, George Nurser, Pierre Rampal, Ad Reniers, Ernesto Rodriguez, Justin Stopa, Céline Tison, Clément Ubelmann, Erik van Sebille, and Jiping Xie
Ocean Sci., 14, 337–354, https://doi.org/10.5194/os-14-337-2018, https://doi.org/10.5194/os-14-337-2018, 2018
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The Sea surface KInematics Multiscale (SKIM) monitoring mission is a proposal for a future satellite that is designed to measure ocean currents and waves. Using a Doppler radar, the accurate measurement of currents requires the removal of the mean velocity due to ocean wave motions. This paper describes the main processing steps needed to produce currents and wave data from the radar measurements. With this technique, SKIM can provide unprecedented coverage and resolution, over the global ocean.
Graham D. Quartly, Jean-François Legeais, Michaël Ablain, Lionel Zawadzki, M. Joana Fernandes, Sergei Rudenko, Loren Carrère, Pablo Nilo García, Paolo Cipollini, Ole B. Andersen, Jean-Christophe Poisson, Sabrina Mbajon Njiche, Anny Cazenave, and Jérôme Benveniste
Earth Syst. Sci. Data, 9, 557–572, https://doi.org/10.5194/essd-9-557-2017, https://doi.org/10.5194/essd-9-557-2017, 2017
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We have produced an improved monthly record of mean sea level for 1993–2015. It is developed by careful processing of the records from nine satellite altimeter missions, making use of the best available orbits, instrumental corrections and geophysical corrections. This paper details the selection process and the processing method. The data are suitable for investigation of sea level changes at scales from seasonal to long-term sea level rise, including interannual variations due to El Niño.
Loren Carrere, Yannice Faugère, and Michaël Ablain
Ocean Sci., 12, 825–842, https://doi.org/10.5194/os-12-825-2016, https://doi.org/10.5194/os-12-825-2016, 2016
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New dynamic atmospheric (DAC_ERA) and dry tropospheric (DT_ERA) correction have been computed for the altimeter period using the ERA-Interim meteorological reanalysis. The corrections improve sea level estimations in Southern Ocean and in shallow waters; the impact is the most important for the first decade of altimetry, when operational meteorological models had a weaker quality. DT_ERA remains better in the recent period. New corrections significantly impact long-term regional trends.
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Co-editor-in-chief
This study is based on observations from the new swath altimetry satellite SWOT. It is the first to describe and characterise internal tides using this new altimetry mission. It therefore highlights the 2D potential of SWOT and opens up new prospects for studying the variability of the internal tide.
This study is based on observations from the new swath altimetry satellite SWOT. It is the...
Short summary
Sea level observations along the swaths of the new SWOT (Surface Water and Ocean Topography) mission were used to characterize internal tides at three semidiurnal frequencies off the Amazon shelf in the tropical Atlantic during the SWOT calibration/validation period. The atlases were derived using harmonic analysis and principal component analysis. The SWOT-derived internal tide atlas outperforms the reference atlas previously used to correct SWOT observations.
Sea level observations along the swaths of the new SWOT (Surface Water and Ocean Topography)...
