Articles | Volume 21, issue 1
https://doi.org/10.5194/os-21-1-2025
© 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-21-1-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Surface circulation characterization along the middle southern coastal region of Vietnam from high-frequency radar and numerical modeling
Thanh Huyen Tran
CORRESPONDING AUTHOR
Laboratory of Oceanology and Geosciences (LOG), UMR 8187, Univ. du Littoral Côte d'Opale, CNRS, Univ. Lille, IRD, Wimereux, France
Land–Ocean–Atmosphere Regional Coupled System Study Center (LOTUS), University of Science and Technology of Hanoi (USTH), Hanoi, Vietnam
Alexei Sentchev
Laboratory of Oceanology and Geosciences (LOG), UMR 8187, Univ. du Littoral Côte d'Opale, CNRS, Univ. Lille, IRD, Wimereux, France
Thai To Duy
Institute of Oceanography, Vietnam Academy of Science and Technology (VAST), Nha Trang, Vietnam
Marine Herrmann
Laboratory of Space Geophysical and Oceanographic Studies (LEGOS), UMR 5566, IRD, CNES, CNRS, UPS, Toulouse, France
Sylvain Ouillon
Land–Ocean–Atmosphere Regional Coupled System Study Center (LOTUS), University of Science and Technology of Hanoi (USTH), Hanoi, Vietnam
Laboratory of Space Geophysical and Oceanographic Studies (LEGOS), UMR 5566, IRD, CNES, CNRS, UPS, Toulouse, France
Kim Cuong Nguyen
Department of Marine Science and Technology, University of Science (HUS), Vietnam National University, Hanoi, Vietnam
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Adrien Garinet, Marine Herrmann, Patrick Marsaleix, and Juliette Pénicaud
Geosci. Model Dev., 17, 6967–6986, https://doi.org/10.5194/gmd-17-6967-2024, https://doi.org/10.5194/gmd-17-6967-2024, 2024
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Mixing is a crucial aspect of the ocean, but its accurate representation in computer simulations is made challenging by errors that result in unwanted mixing, compromising simulation realism. Here we illustrate the spurious effect that tides can have on simulations of south-east Asia. Although they play an important role in determining the state of the ocean, they can increase numerical errors and make simulation outputs less realistic. We also provide insights into how to reduce these errors.
Marine Herrmann, Thai To Duy, and Patrick Marsaleix
Ocean Sci., 20, 1013–1033, https://doi.org/10.5194/os-20-1013-2024, https://doi.org/10.5194/os-20-1013-2024, 2024
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In summer, deep, cold waters rise to the surface along and off the Vietnamese coast. This upwelling of water lifts nutrients, inducing biological activity that is important for fishery resources. Strong tides occur on the shelf off the Mekong Delta. By increasing the mixing of ocean waters and modifying currents, they are a major factor in the development of upwelling on the shelf, accounting for ~75 % of its average summer intensity.
Sloane Bertin, Alexei Sentchev, and Elena Alekseenko
Ocean Sci., 20, 965–980, https://doi.org/10.5194/os-20-965-2024, https://doi.org/10.5194/os-20-965-2024, 2024
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In applications related to search and rescue or pollution mitigation, gaining insights into turbulent processes at a fine scale on the ocean surface is crucial. This research suggests combining numerical model outputs with Lagrangian drifter measurements to enhance the reconstruction of surface current velocity fields. The findings demonstrate a notable enhancement (approximately 50 %) in the model's ability to replicate the movement of passive tracers in the Dover Strait.
Ngoc B. Trinh, Marine Herrmann, Caroline Ulses, Patrick Marsaleix, Thomas Duhaut, Thai To Duy, Claude Estournel, and R. Kipp Shearman
Geosci. Model Dev., 17, 1831–1867, https://doi.org/10.5194/gmd-17-1831-2024, https://doi.org/10.5194/gmd-17-1831-2024, 2024
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A high-resolution model was built to study the South China Sea (SCS) water, heat, and salt budgets. Model performance is demonstrated by comparison with observations and simulations. Important discards are observed if calculating offline, instead of online, lateral inflows and outflows of water, heat, and salt. The SCS mainly receives water from the Luzon Strait and releases it through the Mindoro, Taiwan, and Karimata straits. SCS surface interocean water exchanges are driven by monsoon winds.
Marine Herrmann, Thai To Duy, and Claude Estournel
Ocean Sci., 19, 453–467, https://doi.org/10.5194/os-19-453-2023, https://doi.org/10.5194/os-19-453-2023, 2023
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The South Vietnam upwelling develops in summer along and off the Vietnamese coast. It brings cold and nutrient-rich waters to the surface, allowing photosynthesis essential to marine ecosystems and fishing resources. We show here that its daily variations are mainly due to the wind, thus predictable, in the southern shelf and coastal regions. However, they are more chaotic in the offshore area, and especially in the northern area, due to the influence of eddies of a highly chaotic nature.
Thai To Duy, Marine Herrmann, Claude Estournel, Patrick Marsaleix, Thomas Duhaut, Long Bui Hong, and Ngoc Trinh Bich
Ocean Sci., 18, 1131–1161, https://doi.org/10.5194/os-18-1131-2022, https://doi.org/10.5194/os-18-1131-2022, 2022
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The South Vietnam Upwelling develops in the coastal and offshore regions of the southwestern South China Sea under the influence of summer monsoon winds. Cold, nutrient-rich waters rise to the surface, where photosynthesis occurs and is essential for fishing activity. We have developed a very high-resolution model to better understand the factors that drive the variability of this upwelling at different scales: daily chronology to summer mean of wind and mesoscale to regional circulation.
Violaine Piton, Marine Herrmann, Florent Lyard, Patrick Marsaleix, Thomas Duhaut, Damien Allain, and Sylvain Ouillon
Geosci. Model Dev., 13, 1583–1607, https://doi.org/10.5194/gmd-13-1583-2020, https://doi.org/10.5194/gmd-13-1583-2020, 2020
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Consequences of tidal dynamics on hydro-sedimentary processes are a recurrent issue in estuarine and coastal processes studies, and accurate tidal solutions are a prerequisite for modeling sediment transport. This study presents the implementation and optimization of a model configuration in terms of bathymetry and bottom friction and assess the influence of these parameters on tidal solutions, in a macro-tidal environment: the Gulf of Tonkin (Vietnam).
Abdesselam Megnounif and Sylvain Ouillon
Hydrol. Earth Syst. Sci., 22, 6335–6355, https://doi.org/10.5194/hess-22-6335-2018, https://doi.org/10.5194/hess-22-6335-2018, 2018
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From a classification of river discharge, the effective or dominant discharge is the one whose class corresponds to the maximum sediment supply. The efficiency of the Wadi Sebdou (NW Algeria) was examined over 1973–2004. Two subdivisions allowed a correct distribution of frequencies and supplies of water and sediments. Their effective discharge, close to the
half-load discharge, was compared to analytical values based on statistics and rating curves. Return periods were also explained.
Mohammed Achite and Sylvain Ouillon
Hydrol. Earth Syst. Sci., 20, 1355–1372, https://doi.org/10.5194/hess-20-1355-2016, https://doi.org/10.5194/hess-20-1355-2016, 2016
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Changes of T, P, Q and sediment fluxes in a semi-arid basin little affected by human activities are analyzed from 40 years of measurements. T increased, P decreased, an earlier onset of first summer rains occurred. The flow regime shifted from perennial to intermittent. Sediment flux almost doubled every decade. The sediment regime shifted from two equivalent seasons of sediment delivery to a single major season regime. The C–Q rating curve ability declined due to enhanced hysteresis effects.
V. D. Vinh, S. Ouillon, T. D. Thanh, and L. V. Chu
Hydrol. Earth Syst. Sci., 18, 3987–4005, https://doi.org/10.5194/hess-18-3987-2014, https://doi.org/10.5194/hess-18-3987-2014, 2014
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Approach: Remote Sensing | Properties and processes: Coastal and near-shore processes
Ensemble reconstruction of missing satellite data using a denoising diffusion model: application to chlorophyll a concentration in the Black Sea
A new airborne system for simultaneous high-resolution ocean vector current and wind mapping: first demonstration of the SeaSTAR mission concept in the macrotidal Iroise Sea
Drivers of Laptev Sea interannual variability in salinity and temperature
Alexander Barth, Julien Brajard, Aida Alvera-Azcárate, Bayoumy Mohamed, Charles Troupin, and Jean-Marie Beckers
Ocean Sci., 20, 1567–1584, https://doi.org/10.5194/os-20-1567-2024, https://doi.org/10.5194/os-20-1567-2024, 2024
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Most satellite observations have gaps, for example, due to clouds. This paper presents a method to reconstruct missing data in satellite observations of the chlorophyll a concentration in the Black Sea. Rather than giving a single possible reconstructed field, the discussed method provides an ensemble of possible reconstructions using a generative neural network. The resulting ensemble is validated using techniques from numerical weather prediction and ocean modelling.
David L. McCann, Adrien C. H. Martin, Karlus A. C. de Macedo, Ruben Carrasco Alvarez, Jochen Horstmann, Louis Marié, José Márquez-Martínez, Marcos Portabella, Adriano Meta, Christine Gommenginger, Petronilo Martin-Iglesias, and Tania Casal
Ocean Sci., 20, 1109–1122, https://doi.org/10.5194/os-20-1109-2024, https://doi.org/10.5194/os-20-1109-2024, 2024
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This paper presents the results of the first scientific campaign of a new method to remotely sense the small-scale, fast-evolving dynamics that are vital to our understanding of coastal and shelf sea processes. This work represents the first demonstration of the simultaneous measurement of current and wind vectors from this novel method. Comparisons with other current measuring systems and models around the dynamic area of the Iroise Sea are presented and show excellent agreement.
Phoebe A. Hudson, Adrien C. H. Martin, Simon A. Josey, Alice Marzocchi, and Athanasios Angeloudis
Ocean Sci., 20, 341–367, https://doi.org/10.5194/os-20-341-2024, https://doi.org/10.5194/os-20-341-2024, 2024
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Satellite salinity data are used for the first time to study variability in Arctic freshwater transport from the Lena River and are shown to be a valuable tool for studying this region. These data confirm east/westerly wind is the main control on fresh water and sea ice transport rather than the volume of river runoff. The strong role of the wind suggests understanding how wind patterns will change is key to predicting future Arctic circulation and sea ice concentration.
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Short summary
For the first time, high-resolution surface current data from high-frequency radar have been obtained along the central and southern coasts of Vietnam, and combined with a modelling approach, this is helping scientists to understand coastal processes. The research showed that the surface circulation is driven not only by winds, but also by other factors. This can enrich public knowledge of the coastal dynamics that govern other environmental impacts along the coasts.
For the first time, high-resolution surface current data from high-frequency radar have been...