Articles | Volume 19, issue 12
https://doi.org/10.5194/tc-19-6639-2025
© 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/tc-19-6639-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Arctic regional changes revealed by clustering of sea-ice observations
IMT Atlantique, Lab-STICC, UMR CNRS 6285, 29238, Brest, France
Univ Brest CNRS Ifremer IRD, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Brest, France
Pierre Tandeo
IMT Atlantique, Lab-STICC, UMR CNRS 6285, 29238, Brest, France
ODYSSEY Team-Project, INRIA CNRS, Brest, France
Florian Sévellec
Univ Brest CNRS Ifremer IRD, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Brest, France
ODYSSEY Team-Project, INRIA CNRS, Brest, France
Camille Lique
Univ Brest CNRS Ifremer IRD, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Brest, France
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David Docquier, Giorgia Di Capua, Reik V. Donner, Carlos A. L. Pires, Amélie Simon, and Stéphane Vannitsem
Nonlin. Processes Geophys., 31, 115–136, https://doi.org/10.5194/npg-31-115-2024, https://doi.org/10.5194/npg-31-115-2024, 2024
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Identifying causes of specific processes is crucial in order to better understand our climate system. Traditionally, correlation analyses have been used to identify cause–effect relationships in climate studies. However, correlation does not imply causation, which justifies the need to use causal methods. We compare two independent causal methods and show that these are superior to classical correlation analyses. We also find some interesting differences between the two methods.
Amélie Simon, Coline Poppeschi, Sandra Plecha, Guillaume Charria, and Ana Russo
Ocean Sci., 19, 1339–1355, https://doi.org/10.5194/os-19-1339-2023, https://doi.org/10.5194/os-19-1339-2023, 2023
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In the coastal northeastern Atlantic and for three subregions (the English Channel, Bay of Brest and Bay of Biscay) over the period 1982–2022, marine heatwaves are more frequent and longer and extend over larger areas, while the opposite is seen for marine cold spells. This result is obtained with both in situ and satellite datasets, although the satellite dataset underestimates the amplitude of these extremes.
Amélie Simon, Guillaume Gastineau, Claude Frankignoul, Vladimir Lapin, and Pablo Ortega
Weather Clim. Dynam., 3, 845–861, https://doi.org/10.5194/wcd-3-845-2022, https://doi.org/10.5194/wcd-3-845-2022, 2022
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The influence of the Arctic sea-ice loss on atmospheric circulation in midlatitudes depends on persistent sea surface temperatures in the North Pacific. In winter, Arctic sea-ice loss and a warm North Pacific Ocean both induce depressions over the North Pacific and North Atlantic, an anticyclone over Greenland, and a stratospheric anticyclone over the Arctic. However, the effects are not additive as the interaction between both signals is slightly destructive.
Noemie Planat, Carolina Olivia Dufour, Camille Lique, Jan Klaus Rieck, Claude Talandier, and L. Bruno Tremblay
EGUsphere, https://doi.org/10.5194/egusphere-2025-3527, https://doi.org/10.5194/egusphere-2025-3527, 2025
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We detect and track mesoscale eddies in the Canadian Basin of the Arctic Ocean and describe their spatio-temporal characteristics in a high resolution pan-Arctic model. Results show eddies of typical size 12 km, lasting 10 days and travelling 11 km, with roughly an equal number of cyclones and anticyclones detected. Seasonal, decadal and interannual changes of the number of eddies detected show strong correlations with the ice cover, and with the mean circulation of the basin.
Arthur Coquereau, Florian Sévellec, Thierry Huck, Joël J.-M. Hirschi, and Quentin Jamet
EGUsphere, https://doi.org/10.5194/egusphere-2025-17, https://doi.org/10.5194/egusphere-2025-17, 2025
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Using statistical methods and a set of ensemble climate models, we decompose the sources of Atlantic Meridional Overturning Circulation (AMOC) variance. Three distinct phases of physical variability are identified: from 1850 to 1990, internal variability dominates; from 1990 to 2050, dynamical adjustment related to AMOC decline takes over; after 2050, differences between forcing scenarios become dominant. Beyond these physical factors, model variability remains the major source of uncertainty.
Sofia Allende, Anne Marie Treguier, Camille Lique, Clément de Boyer Montégut, François Massonnet, Thierry Fichefet, and Antoine Barthélemy
Geosci. Model Dev., 17, 7445–7466, https://doi.org/10.5194/gmd-17-7445-2024, https://doi.org/10.5194/gmd-17-7445-2024, 2024
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We study the parameters of the turbulent-kinetic-energy mixed-layer-penetration scheme in the NEMO model with regard to sea-ice-covered regions of the Arctic Ocean. This evaluation reveals the impact of these parameters on mixed-layer depth, sea surface temperature and salinity, and ocean stratification. Our findings demonstrate significant impacts on sea ice thickness and sea ice concentration, emphasizing the need for accurately representing ocean mixing to understand Arctic climate dynamics.
Paul Platzer, Pierre Ailliot, Bertrand Chapron, and Pierre Tandeo
Clim. Past, 20, 2267–2286, https://doi.org/10.5194/cp-20-2267-2024, https://doi.org/10.5194/cp-20-2267-2024, 2024
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Old observations are necessary to understand the atmosphere. When direct observations are not available, one can use indirect observations, such as tide gauges, which measure the sea level in port cities. The sea level rises when local air pressure decreases and when wind pushes water towards the coast. Several centuries-long tide gauge records are available. We show that these can be complementary to direct pressure observations for studying storms and anticyclones in the 19th century.
Pierre Le Bras, Florian Sévellec, Pierre Tandeo, Juan Ruiz, and Pierre Ailliot
Nonlin. Processes Geophys., 31, 303–317, https://doi.org/10.5194/npg-31-303-2024, https://doi.org/10.5194/npg-31-303-2024, 2024
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The goal of this paper is to weight several dynamic models in order to improve the representativeness of a system. It is illustrated using a set of versions of an idealized model describing the Atlantic Meridional Overturning Circulation. The low-cost method is based on data-driven forecasts. It enables model performance to be evaluated on their dynamics. Taking into account both model performance and codependency, the derived weights outperform benchmarks in reconstructing a model distribution.
David Docquier, Giorgia Di Capua, Reik V. Donner, Carlos A. L. Pires, Amélie Simon, and Stéphane Vannitsem
Nonlin. Processes Geophys., 31, 115–136, https://doi.org/10.5194/npg-31-115-2024, https://doi.org/10.5194/npg-31-115-2024, 2024
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Identifying causes of specific processes is crucial in order to better understand our climate system. Traditionally, correlation analyses have been used to identify cause–effect relationships in climate studies. However, correlation does not imply causation, which justifies the need to use causal methods. We compare two independent causal methods and show that these are superior to classical correlation analyses. We also find some interesting differences between the two methods.
Amélie Simon, Coline Poppeschi, Sandra Plecha, Guillaume Charria, and Ana Russo
Ocean Sci., 19, 1339–1355, https://doi.org/10.5194/os-19-1339-2023, https://doi.org/10.5194/os-19-1339-2023, 2023
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In the coastal northeastern Atlantic and for three subregions (the English Channel, Bay of Brest and Bay of Biscay) over the period 1982–2022, marine heatwaves are more frequent and longer and extend over larger areas, while the opposite is seen for marine cold spells. This result is obtained with both in situ and satellite datasets, although the satellite dataset underestimates the amplitude of these extremes.
Anne Marie Treguier, Clement de Boyer Montégut, Alexandra Bozec, Eric P. Chassignet, Baylor Fox-Kemper, Andy McC. Hogg, Doroteaciro Iovino, Andrew E. Kiss, Julien Le Sommer, Yiwen Li, Pengfei Lin, Camille Lique, Hailong Liu, Guillaume Serazin, Dmitry Sidorenko, Qiang Wang, Xiaobio Xu, and Steve Yeager
Geosci. Model Dev., 16, 3849–3872, https://doi.org/10.5194/gmd-16-3849-2023, https://doi.org/10.5194/gmd-16-3849-2023, 2023
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The ocean mixed layer is the interface between the ocean interior and the atmosphere and plays a key role in climate variability. We evaluate the performance of the new generation of ocean models for climate studies, designed to resolve
ocean eddies, which are the largest source of ocean variability and modulate the mixed-layer properties. We find that the mixed-layer depth is better represented in eddy-rich models but, unfortunately, not uniformly across the globe and not in all models.
Pierre Tandeo, Pierre Ailliot, and Florian Sévellec
Nonlin. Processes Geophys., 30, 129–137, https://doi.org/10.5194/npg-30-129-2023, https://doi.org/10.5194/npg-30-129-2023, 2023
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Robin Marcille, Maxime Thiébaut, Pierre Tandeo, and Jean-François Filipot
Wind Energ. Sci., 8, 771–786, https://doi.org/10.5194/wes-8-771-2023, https://doi.org/10.5194/wes-8-771-2023, 2023
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A novel data-driven method is proposed to design an optimal sensor network for the reconstruction of offshore wind resources. Based on unsupervised learning of numerical weather prediction wind data, it provides a simple yet efficient method for the siting of sensors, outperforming state-of-the-art methods for this application. It is applied in the main French offshore wind energy development areas to provide guidelines for the deployment of floating lidars for wind resource assessment.
Guillaume Boutin, Einar Ólason, Pierre Rampal, Heather Regan, Camille Lique, Claude Talandier, Laurent Brodeau, and Robert Ricker
The Cryosphere, 17, 617–638, https://doi.org/10.5194/tc-17-617-2023, https://doi.org/10.5194/tc-17-617-2023, 2023
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Sea ice cover in the Arctic is full of cracks, which we call leads. We suspect that these leads play a role for atmosphere–ocean interactions in polar regions, but their importance remains challenging to estimate. We use a new ocean–sea ice model with an original way of representing sea ice dynamics to estimate their impact on winter sea ice production. This model successfully represents sea ice evolution from 2000 to 2018, and we find that about 30 % of ice production takes place in leads.
Juan Ruiz, Pierre Ailliot, Thi Tuyet Trang Chau, Pierre Le Bras, Valérie Monbet, Florian Sévellec, and Pierre Tandeo
Geosci. Model Dev., 15, 7203–7220, https://doi.org/10.5194/gmd-15-7203-2022, https://doi.org/10.5194/gmd-15-7203-2022, 2022
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We present a new approach to validate numerical simulations of the current climate. The method can take advantage of existing climate simulations produced by different centers combining an analog forecasting approach with data assimilation to quantify how well a particular model reproduces a sequence of observed values. The method can be applied with different observations types and is implemented locally in space and time significantly reducing the associated computational cost.
Etienne Pauthenet, Loïc Bachelot, Kevin Balem, Guillaume Maze, Anne-Marie Tréguier, Fabien Roquet, Ronan Fablet, and Pierre Tandeo
Ocean Sci., 18, 1221–1244, https://doi.org/10.5194/os-18-1221-2022, https://doi.org/10.5194/os-18-1221-2022, 2022
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Temperature and salinity profiles are essential for studying the ocean’s stratification, but there are not enough of these data. Satellites are able to measure daily maps of the surface ocean. We train a machine to learn the link between the satellite data and the profiles in the Gulf Stream region. We can then use this link to predict profiles at the high resolution of the satellite maps. Our prediction is fast to compute and allows us to get profiles at any locations only from surface data.
Amélie Simon, Guillaume Gastineau, Claude Frankignoul, Vladimir Lapin, and Pablo Ortega
Weather Clim. Dynam., 3, 845–861, https://doi.org/10.5194/wcd-3-845-2022, https://doi.org/10.5194/wcd-3-845-2022, 2022
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The influence of the Arctic sea-ice loss on atmospheric circulation in midlatitudes depends on persistent sea surface temperatures in the North Pacific. In winter, Arctic sea-ice loss and a warm North Pacific Ocean both induce depressions over the North Pacific and North Atlantic, an anticyclone over Greenland, and a stratospheric anticyclone over the Arctic. However, the effects are not additive as the interaction between both signals is slightly destructive.
Guillaume Boutin, Timothy Williams, Pierre Rampal, Einar Olason, and Camille Lique
The Cryosphere, 15, 431–457, https://doi.org/10.5194/tc-15-431-2021, https://doi.org/10.5194/tc-15-431-2021, 2021
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In this study, we investigate the interactions of surface ocean waves with sea ice. We focus on the evolution of sea ice after it has been fragmented by the waves. Fragmented sea ice is expected to experience less resistance to deformation. We reproduce this evolution using a new coupling framework between a wave model and the recently developed sea ice model neXtSIM. We find that waves can significantly increase the mobility of compact sea ice over wide areas in the wake of storm events.
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Short summary
Through a machine learning technique based on seasonal cycles of sea-ice concentration from satellite data over the last 4 decades, our research shows that four regions are sufficient to best regionalize the Arctic. These regions are mainly organized into latitudinal bands and evolve in time and space. The descriptor proposed to monitor Arctic sea-ice changes is the probability to belong to each region. The probability to belong to the permanent sea-ice regions has decreased by 3.1 % per decade.
Through a machine learning technique based on seasonal cycles of sea-ice concentration from...