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43 results on '"Alory, Gaël"'

1. Oceans

Author

Dadou, Isabelle, Alory, Gael, Dieng, Habib B., Chaussard, Estelle, editor, Jones, Cathleen, editor, Chen, Jingyi Ann, editor, and Donnellan, Andrea, editor

Published
2024
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7. Joint observation–model mixed-layer heat and salt budgets in the eastern tropical Atlantic

Author

Ngakala, Roy Dorgeless, Alory, Gaël, Da-Allada, Casimir Yélognissè, Kom, Olivia Estelle, Jouanno, Julien, Rath, Willi, Baloïtcha, Ezinvi, Ngakala, Roy Dorgeless, Alory, Gaël, Da-Allada, Casimir Yélognissè, Kom, Olivia Estelle, Jouanno, Julien, Rath, Willi, and Baloïtcha, Ezinvi

Abstract

In this study, we use a joint observation-model approachto investigate the mixed-layer heat and salt annual mean as well as seasonalbudgets in the eastern tropical Atlantic. The regional PREFCLIM (PREFACE Climatology)observational climatology provides the budget terms with a relatively lowspatial and temporal resolution compared to the online NEMO (Nucleus for European Modelingof the Ocean; Madec, G., 2014) model, and thisis later resampled as in PREFCLIM climatology. In addition, advectionterms are recomputed offline from the model as PREFCLIM gridded advectioncomputation. In the Senegal, Angola, and Benguela regions, the seasonal cycle ofmixed-layer temperature is mainly governed by surface heat fluxes; however,it is essentially driven by vertical heat diffusion in the equatorial region.The seasonal cycle of mixed-layer salinity is largely controlled byfreshwater flux in the Senegal and Benguela regions; however, it follows thevariability of zonal and meridional salt advection in the equatorial and Angolaregions, respectively. Our results show that the time-averaged spatialdistribution of NEMO offline heat and salt advection terms compares much betterto PREFCLIM horizontal advection terms than the online heat and salt advectionterms. However, the seasonal cycle of horizontal advection in selectedregions shows that NEMO offline terms do not always compare well withPREFCLIM, sometimes less than online terms. Despite this difference, theseresults suggest the important role of small-scale variability in mixed-layerheat and salt budgets.

Published
2023
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8. Physical processes and biological productivity in the upwelling regions of the tropical Atlantic

Author

Brandt, Peter, Alory, Gaël, Awo, Founi Mesmin, Dengler, Marcus, Djakouré, Sandrine, Imbol Koungue, Rodrigue Anicet, Jouanno, Julien, Körner, Mareike, Roch, Marisa, Rouault, Mathieu, Brandt, Peter, Alory, Gaël, Awo, Founi Mesmin, Dengler, Marcus, Djakouré, Sandrine, Imbol Koungue, Rodrigue Anicet, Jouanno, Julien, Körner, Mareike, Roch, Marisa, and Rouault, Mathieu

Abstract

In this paper, we review observational and modelling results on the upwelling in the tropical Atlantic between 10∘ N and 20∘ S. We focus on the physical processes that drive the seasonal variability of surface cooling and the upward nutrient flux required to explain the seasonality of biological productivity. We separately consider the equatorial upwelling system, the coastal upwelling system of the Gulf of Guinea and the tropical Angolan upwelling system. All three tropical Atlantic upwelling systems have in common a strong seasonal cycle, with peak biological productivity during boreal summer. However, the physical processes driving the upwelling vary between the three systems. For the equatorial regime, we discuss the wind forcing of upwelling velocity and turbulent mixing, as well as the underlying dynamics responsible for thermocline movements and current structure. The coastal upwelling system in the Gulf of Guinea is located along its northern boundary and is driven by both local and remote forcing. Particular emphasis is placed on the Guinea Current, its separation from the coast and the shape of the coastline. For the tropical Angolan upwelling, we show that this system is not driven by local winds but instead results from the combined effect of coastally trapped waves, surface heat and freshwater fluxes, and turbulent mixing. Finally, we review recent changes in the upwelling systems associated with climate variability and global warming and address possible responses of upwelling systems in future scenarios.

Published
2023
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9. Sea Surface Salinity Observations from Space with the SMOS Satellite: A New Means to Monitor the Marine Branch of the Water Cycle

Author

Reul, Nicolas, Fournier, Severine, Boutin, Jaqueline, Hernandez, Olga, Maes, Christophe, Chapron, Bertrand, Alory, Gaël, Quilfen, Yves, Tenerelli, Joseph, Morisset, Simmon, Kerr, Yann, Mecklenburg, Susanne, Delwart, Steven, Bengtsson, Lennart, editor, Bonnet, R.-M., editor, Calisto, M., editor, Destouni, G., editor, Gurney, R., editor, Johannessen, J., editor, Kerr, Y., editor, Lahoz, W.A., editor, and Rast, M., editor

Published
2014
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10. Physical processes in the upwelling regions of the tropical Atlantic

Author

Brandt, Peter, primary, Alory, Gaël, additional, Awo, Founi Mesmin, additional, Dengler, Marcus, additional, Djakouré, Sandrine, additional, Imbol Koungue, Rodrigue Anicet, additional, Jouanno, Julien, additional, Körner, Mareike, additional, Roch, Marisa, additional, and Rouault, Mathieu, additional

Published
2022
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12. Physical processes in the upwelling regions of the tropical Atlantic

Author

Brandt, Peter, Alory, Gaël, Awo, Founi Mesmin, Dengler, Marcus, Djakouré, Sandrine, Imbol Koungue, Rodrigue Anicet, Jouanno, Julien, Körner, Mareike, Roch, Marisa, Rouault, Mathieu, Brandt, Peter, Alory, Gaël, Awo, Founi Mesmin, Dengler, Marcus, Djakouré, Sandrine, Imbol Koungue, Rodrigue Anicet, Jouanno, Julien, Körner, Mareike, Roch, Marisa, and Rouault, Mathieu

Abstract

In this paper, we review observational and modelling results on the upwelling in the inner tropical Atlantic. We focus on the physical processes that drive the seasonal variability of surface cooling and upward nutrient flux required to explain the seasonality of primary productivity. We separately consider the equatorial upwelling system, the northern coastal upwelling system of the Gulf of Guinea and the tropical Angolan upwelling system. For the equatorial regime, we discuss the forcing of upwelling velocity and turbulent mixing as well as the underlying dynamics responsible for thermocline movements and current structure. The coastal upwelling system in the Gulf of Guinea is concentrated along northern boundary and is driven by both, local and remote forcing. The particular role of the Guinea Current, nonlinearity and the shape of the coastline are emphasized. For the tropical Angolan upwelling, we show that this system is not wind-driven, but instead results from the combined effect of coastally trapped waves, surface heat and freshwater fluxes, and turbulent mixing. Finally, we review recent changes in the upwelling systems associated with climate variability and global warming and address possible responses of upwelling systems in future scenarios.

Published
2022
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17. Global Analysis of Coastal Gradients of Sea Surface Salinity

Author

Dossa, Alina N., Alory, Gaël, Costa Da Silva, Alex, Dahunsi, Adeola M., Bertrand, Arnaud, Dossa, Alina N., Alory, Gaël, Costa Da Silva, Alex, Dahunsi, Adeola M., and Bertrand, Arnaud

Abstract

Sea surface salinity (SSS) is a key variable for ocean–atmosphere interactions and the water cycle. Due to its climatic importance, increasing efforts have been made for its global in situ observation, and dedicated satellite missions have been launched more recently to allow homogeneous coverage at higher resolution. Cross-shore SSS gradients can bear the signature of different coastal processes such as river plumes, upwelling or boundary currents, as we illustrate in a few regions. However, satellites performances are questionable in coastal regions. Here, we assess the skill of four gridded products derived from the Soil Moisture Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) satellites and the GLORYS global model reanalysis at capturing cross-shore SSS gradients in coastal bands up to 300 km wide. These products are compared with thermosalinography (TSG) measurements, which provide continuous data from the open ocean to the coast along ship tracks. The comparison shows various skills from one product to the other, decreasing as the coast gets closer. The bias in reproducing coastal SSS gradients is unrelated to how the SSS biases evolve with the distance to the coast. Despite limited skill, satellite products generally agree better with collocated TSG data than a global reanalysis and show a large range of coastal SSS gradients with different signs. Moreover, satellites reveal a global dominance of coastal freshening, primarily related to river runoff over shelves. This work shows a great potential of SSS remote sensing to monitor coastal processes, which would, however, require a jump in the resolution of future SSS satellite missions to be fully exploited.

Published
2021
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19. Sea Surface Salinity Observations from Space with the SMOS Satellite: A New Means to Monitor the Marine Branch of the Water Cycle

Author

Reul, Nicolas, primary, Fournier, Severine, additional, Boutin, Jaqueline, additional, Hernandez, Olga, additional, Maes, Christophe, additional, Chapron, Bertrand, additional, Alory, Gaël, additional, Quilfen, Yves, additional, Tenerelli, Joseph, additional, Morisset, Simmon, additional, Kerr, Yann, additional, Mecklenburg, Susanne, additional, and Delwart, Steven, additional

Published
2013
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21. Le Service national d'observation de la salinité de surface de la mer : 50 ans de mesures océaniques globales

Author

Alory, Gaël, primary, Téchiné, Philippe, additional, Delcroix, Thierry, additional, Diverrès, Denis, additional, Varillon, David, additional, Donguy, Jean-René, additional, Reverdin, Gilles, additional, Morrow, Rosemary, additional, Grelet, Jacques, additional, Gouriou, Yves, additional, Jacquin, Stéphane, additional, Kestenare, Elodie, additional, Bachelier, Céline, additional, and DiMattéo, Angelo, additional

Published
2020
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23. Ship-Based Contributions to Global Ocean, Weather, and Climate Observing Systems

Author

Smith, Shawn R., Alory, Gaël, Andersson, Axel, Asher, William, Baker, Alex, Berry, David I., Drushka, Kyla, Figurskey, Darin, Freeman, Eric, Holthus, Paul, Jickells, Tim, Kleta, Henry, Kent, Elizabeth C., Kolodziejczyk, Nicolas, Kramp, Martin, Loh, Zoe, Poli, Paul, Schuster, Ute, Steventon, Emma, Swart, Sebastiaan, Tarasova, Oksana, Petit De La Villeon, Loic, Vinogradova-shiffer, Nadya, Smith, Shawn R., Alory, Gaël, Andersson, Axel, Asher, William, Baker, Alex, Berry, David I., Drushka, Kyla, Figurskey, Darin, Freeman, Eric, Holthus, Paul, Jickells, Tim, Kleta, Henry, Kent, Elizabeth C., Kolodziejczyk, Nicolas, Kramp, Martin, Loh, Zoe, Poli, Paul, Schuster, Ute, Steventon, Emma, Swart, Sebastiaan, Tarasova, Oksana, Petit De La Villeon, Loic, and Vinogradova-shiffer, Nadya

Abstract

The role ships play in atmospheric, oceanic, and biogeochemical observations is described with a focus on measurements made near the ocean surface. Ships include merchant and research vessels; cruise liners and ferries; fishing vessels; coast guard, military, and other government-operated ships; yachts; and a growing fleet of automated surface vessels. The present capabilities of ships to measure essential climate/ocean variables and the requirements from a broad community to address operational, commercial, and scientific needs are described. The authors provide a vision to expand observations needed from ships to understand and forecast the exchanges across the ocean–atmosphere interface. The vision addresses (1) recruiting vessels to improve both spatial and temporal sampling, (2) conducting multivariate sampling on ships, (3) raising technology readiness levels of automated shipboard sensors and ship-to-shore data communications, (4) advancing quality evaluation of observations, and (5) developing a unified data management approach for observations and metadata that meet the needs of a diverse user community. Recommendations are made focusing on integrating private and autonomous vessels into the observing system, investing in sensor and communications technology development, developing an integrated data management structure that includes all types of ships, and moving toward a quality evaluation process that will result in a subset of ships being defined as mobile reference ships that will support climate studies. We envision a future where commercial, research, and privately owned vessels are making multivariate observations using a combination of automated and human-observed measurements. All data and metadata will be documented, tracked, evaluated, distributed, and archived to benefit users of marine data. This vision looks at ships as a holistic network, not a set of disparate commercial, research, and/or third-party activities working in isolation, to bri

Published
2019
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24. North Atlantic subpolar gyre along predetermined ship tracks since 1993 : a monthly data set of surface temperature, salinity, and density

Author

Reverdin, G., Valdimarsson, H., Alory, Gaël, Diverrès, Denis, Bringas, F., Goni, G., Heilmann, L., Chafik, L., Szekely, T., and Friedman, A. R.

Abstract

We present a binned product of sea surface temperature, sea surface salinity, and sea surface density data in the North Atlantic subpolar gyre from 1993 to 2017 that resolves seasonal variability along specific ship routes (

Published
2018

25. Ship-Based Contributions to Global Ocean, Weather, and Climate Observing Systems

Author

Smith, Shawn R., primary, Alory, Gaël, additional, Andersson, Axel, additional, Asher, William, additional, Baker, Alex, additional, Berry, David I., additional, Drushka, Kyla, additional, Figurskey, Darin, additional, Freeman, Eric, additional, Holthus, Paul, additional, Jickells, Tim, additional, Kleta, Henry, additional, Kent, Elizabeth C., additional, Kolodziejczyk, Nicolas, additional, Kramp, Martin, additional, Loh, Zoe, additional, Poli, Paul, additional, Schuster, Ute, additional, Steventon, Emma, additional, Swart, Sebastiaan, additional, Tarasova, Oksana, additional, de la Villéon, Loic Petit, additional, and Vinogradova-Shiffer, Nadya, additional

Published
2019
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26. CORIOLIS. Rapport d’activités 2016

Author

Pouliquen, Sylvie, Maze, Guillaume, Lebreton, Nathanaele, D'Ortenzio, Fabrizio, Alory, Gaël, Delcroix, Thierry, Bourles, Bernard, Blouch, Pierre, Guinet, Christophe, Gouriou, Yves, Gaillard, Fabienne, Heyndrickx, Céline, Le Menn, Marc, Testor, Pierre, Donato, Vincent, Charria, Guillaume, Carval, Thierry, Reverdin, Gilles, and Emzivat, Gilbert

Abstract

Rapport d'activité Coriolis pour l'année 2016 dans le cadre de la convention cadre Coriolis 2014-2020

Published
2017

27. Sea surface temperature patterns in the Tropical Atlantic : principal component analysis and nonlinear principal component analysis

Author

Kenfack, C. S., Mkankam, F. K., Alory, Gaël, Penhoat, Yves du, Hounkonnou, M. N., Vondou, D. A., and Nfor, B. G.

Subjects
PCA, Tropical Ocean, NLPCA, Physics::Atmospheric and Oceanic Physics, Physics::Geophysics, SST
Abstract

The tropical Atlantic Ocean exhibits several modes of interannual variability such as the equatorial (or Atlantic Nino) mode, and meridional (or Atlantic dipole) mode. Nonlinear principal component analysis (NLPCA) is applied on detrended monthly Sea Surface Temperature Anomaly (SSTA) data from the tropical Atlantic Ocean (30 degrees W - 20 degrees E, 26 degrees S - 22 degrees N) for the period 1950 to 2005. The objective is to compare the modes extracted through this statistical analysis to those previously extracted through simpler principal component analysis (PCA). It is shown that the first NLPCA mode explains 38% of the total SST variance compared to 36% by the first PCA while the second NLPCA mode explains 22% of the total SST variance compared to 16% by the second PCA. The first two NLPCA modes marginally explain more of the total data variance than the first two PCA modes. Our analysis confirms results from previous studies and, in addition, shows that the Atlantic El Nino structure is spatially more stable than the Atlantic dipole structure.

Published
2017

30. Variability of the Tropical Atlantic and Pacific SSS Minimum Zones and Their Relations to the ITCZ and SPCZ (1979-2013)

Author

Delcroix, Thierry, Tchilibou, Michel, Alory, Gaël, Reverdin, Gilles, Arnault, Sabine, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Interactions et Processus au sein de la couche de Surface Océanique (IPSO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Variabilité de l'Océan et de la Glace de mer (VOG), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636))

Subjects
[PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2015

31. Sea surface salinity structure of the meandering Gulf Stream revealed by SMOS sensor

Author

Reul, Nicolas, Chapron, Bertrand, Lee, T., Donlon, C., Boutin, Jacqueline, Alory, Gaël, Laboratoire d’Oéanographie Spatiale [Plouzané] (LOS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), European Space Agency (ESA), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
seasonal variability, Gulf Stream, rings and meanders, multisensor synergy, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], sea surface salinity, SMOS
Abstract

International audience; Measurements from the Soil Moisture Ocean Salinity (SMOS) satellite acquired during 2012 in the western North Atlantic are used to reveal the evolution of the sea surface salinity (SSS) structure of the meandering Gulf Stream with an unprecedented space and time resolution. Combined with in situ surface and profile measurements, satellite-derived surface currents, sea surface height (SSH), surface temperature (SST), and chlorophyll (Chl) data, SMOS SSS observations are shown to coherently delineate meanders pinching off from the current to form well-identified salty- (warm-) and fresh- (cold-) core Gulf Stream rings. A covariance analysis at two locations along the separated Gulf stream path (south of Nova Scotia and in the Gulf Stream Extension) reveals a systematically higher correlation between SSS and sea level variability than between SST and SSH during the warmer half of the year. Within (75°W–40°W; 30°N–50°N), Chl concentration is also found to significantly depend on the SSS as SST increases above 20°C.

Published
2014

33. Seasonal mixed-layer salinity balance in the tropical Atlantic Ocean: Mean state and seasonal cycle

Author

Da-Allada, Casimir, Alory, Gaël, Du Penhoat, Yves, Kestenare, Elodie, Durand, Fabien, Hounkonnou, Norbert, Océan du Large et Variabilité Climatique (OLVAC), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Echanges Côte-Large (ECOLA), Institut de Recherche pour le Développement (IRD), ICPMA, University of Abomey Calavi (UAC), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Université d’Abomey-Calavi = University of Abomey Calavi (UAC)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere
Abstract

International audience; We investigate the causes of the seasonal cycle of the near-surface salinity using a mixed-layer salinity model and a combination of satellite products, atmospheric reanalyses, and in situ observations for the period 2000-2008, in the tropical Atlantic Ocean. We find that the balance differs from one region to another. In the western tropical Atlantic, it is controlled by horizontal advection from March to November and by freshwater flux and entrainment for the rest of the year. In the central tropical Atlantic, it is mainly due to the strong contribution of precipitation in agreement with previous results. In the northeastern tropical Atlantic, all terms contribute to the mixed layer salinity between December and March; during the rest of the year, precipitation and zonal advection mainly control the balance. In the Gulf of Guinea, it is driven by freshwater flux from October to February; from March to July, it is controlled by horizontal advection and entrainment; from August to September, mixed-layer salinity variability is weak. Finally, in the Congo region, it is driven by freshwater flux (precipitation and runoff from Congo River) from September to December, by horizontal advection during January to March, and by vertical entrainment during the rest of the year (April to August). There are some discrepancies between observed and modeled salinity tendencies. Some of them are due to our model formulation, which does not explicitly account for the effect of vertical diffusion. Uncertainties of observation products, which force the model, are also sources of errors.

Published
2013

34. Seasonal dynamics of sea surface salinity off Panama: The far Eastern Pacific Fresh Pool

Author

Alory, Gaël, Maes, Christophe, Delcroix, Thierry, Reul, Nicolas, Illig, Serena, Océan du Large et Variabilité Climatique (OLVAC), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire d'Océanographie Spatiale (LOS), Echanges Côte-Large (ECOLA), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
TEMPERATURE DE SURFACE, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, SALINITE, VARIATION SAISONNIERE, DONNEES SATELLITE, Panama, land-ocean-atmosphere interactions, INTERACTION OCEAN ATMOSPHERE, sea surface salinity, seasonal
Abstract

International audience; The freshest surface waters in the tropical Pacific are found at its eastern boundary. Using in situ observations, we depict the quasi-permanent presence of a far eastern Pacific fresh pool with sea surface salinity (SSS) lower than 33, which is confined between Panama's west coast and 85°W in December and extends westward to 95°W in April. Strong SSS fronts are found at the outer edge of this fresh pool. We investigate the seasonal dynamics of the fresh pool using complementary satellite wind, rain, sea level and in situ oceanic current data at the surface, along with hydrographic profiles. The fresh pool appears off Panama due to the strong summer rains associated with the northward migration of the ITCZ over Central America in June. During the second half of the year, the eastward-flowing North Equatorial Counter-Current keeps it trapped to the coast and strengthens the SSS front on its western edge. During winter, as the ITCZ moves southward, the northeasterly Panama gap wind creates a southwestward jet-like current in its path with a dipole of Ekman pumping/eddies on its flanks. As a result, upwelling in the Panama Bight brings to the surface cold and salty waters which erode the fresh pool on its eastern side while both the jet current and the enhanced South Equatorial Current stretch the fresh pool westward until it nearly disappears in May. New SMOS satellite SSS data proves able to capture the main seasonal features of the fresh pool and monitor its spatial extent.

Published
2012

38. Zonal and meridional mass redistribution at ENSO and decadal timescales in the tropical Pacific

Author

Alory, Gaël, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Université Paris 6, and Thierry Delcroix (IRD)

Subjects
ZONE TROPICALE, VARIABILITE INTERANNUELLE, OCEAN PACIFIQUE, [SDE.MCG]Environmental Sciences/Global Changes, NIVEAU DE LA MER, MODEL, MODELE, MASS TRANSPORT, DECADAL VARIABILITY, EL NINO, TROPICAL PACIFIC, VARIABILITE DECENNALE, INTERANNUAL VARIABILITY, TRANSPORT DE MASSE, SEA LEVEL
Abstract

The main modes of interannual climate variability in the tropical Pacific are identified using satellite data for the 1993-99 period and a linear model forced by observed wind for the 1964-99 period. The first mode is typical of ENSO variability. It consists of a zonal seesaw pattern in sea level around a fulcrum at the dateline, associated with an equatorial patch of zonal wind centered near the dateline. The second mode consists of a meridional seesaw pattern in sea level around a fulcrum at 5°N, associated with opposite zonal wind anomalies in the northwestern and southeastern parts of the tropical Pacific. The second mode, particularly active during the very strong 1982-83 and 1997-98 El Niño events, statistically leads ENSO by several months. Its temporal function seems to include a decadal component. Mass transports (0-200 m) associated with both modes of variability are simulated. The first mode is characterised by predominant zonal transports. The second mode, mainly associated with meridional geostrophic transports across 5°N, can be described as a low-frequency, asymmetric recharge oscillator.An OGCM forced by atmospheric reanalysis is then used for the 1951-99 period. It proves able to reproduce the modes of variability described above. The model outputs are validated against surface currents, warm water transports, dynamic height and sea level data. The simulated dynamic height includes a partly artificial linear trend. The origin of this trend is identified in the wind forcing. Subtropical cells, which may play an important role in the decadal variability of the tropical Pacific are simulated. The model shows, in agreement with available data, that the increase of the equatorial SST during the last decades could be linked to a decrease of the meridional transports in the pycnocline.; Les deux principaux modes de variabilité interannuelle en niveau de la mer et vent zonal sont mis en évidence à l’aide de données satellitaires sur la période 1993-99 et d’un modèle linéaire forcé par les vents observés sur la période 1964-99. Le premier mode, caractéristique d’ENSO, consiste en un basculement zonal de niveau de la mer autour de la ligne de changement de date, associé à des anomalies de vent équatorial à la même longitude.Le second mode consiste en un basculement méridien de niveau de la mer autour de 5°N, associé à des anomalies de vent de signe opposé dans le nord-ouest et le sud-est du Pacifique tropical. Ce second mode, statistiquement précurseur d’ENSO, semble inclure une composante décennale. Il est particulièrement actif pendant les forts événements El Niño de 1982-83 et 1997-98. Les transports (0-200m) associés à ces deux modes sont calculés à l’aide du modèle. Le premier mode est essentiellement lié à des transports zonaux. Le second mode, qui s’apparente à une version asymétrique et basse fréquence de la théorie de l’oscillateur rechargé, fait intervenir principalement le transport géostrophique à 5°N dans le milieu du bassin.Un OGCM, dont le forçage atmosphérique est issu de réanalyses, est utilisé ensuite sur la période 1951-99. Il reproduit les modes de variabilité décrits précédemment. Le modèle est validé à l’aide de données de courants de surface, transports, hauteur dynamique et niveau de la mer. La hauteur dynamique simulée montre une tendance linéaire en partie artificielle.L’origine de cette tendance est identifiée dans le forçage en vent. Les cellules méridiennes de circulation subtropicale, qui joueraient un rôle important dans la variabilité décennale du Pacifique tropical, sont simulées. Le modèle montre, en accord avec certaines données, que l’augmentation de la SST équatoriale durant les dernières décennies pourrait être liée à la baisse de la convergence des transports dans la pycnocline.

Published
2002

39. Redistribution zonale et méridienne de masse aux échelles ENSO et décennale dans le Pacifique tropical

Author

Alory, Gaël, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Paris 6, Thierry Delcroix (IRD), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
ZONE TROPICALE, VARIABILITE INTERANNUELLE, OCEAN PACIFIQUE, [SDE.MCG]Environmental Sciences/Global Changes, NIVEAU DE LA MER, MODEL, MODELE, MASS TRANSPORT, DECADAL VARIABILITY, EL NINO, TROPICAL PACIFIC, VARIABILITE DECENNALE, INTERANNUAL VARIABILITY, TRANSPORT DE MASSE, SEA LEVEL
Abstract

The main modes of interannual climate variability in the tropical Pacific are identified using satellite data for the 1993-99 period and a linear model forced by observed wind for the 1964-99 period. The first mode is typical of ENSO variability. It consists of a zonal seesaw pattern in sea level around a fulcrum at the dateline, associated with an equatorial patch of zonal wind centered near the dateline. The second mode consists of a meridional seesaw pattern in sea level around a fulcrum at 5°N, associated with opposite zonal wind anomalies in the northwestern and southeastern parts of the tropical Pacific. The second mode, particularly active during the very strong 1982-83 and 1997-98 El Niño events, statistically leads ENSO by several months. Its temporal function seems to include a decadal component. Mass transports (0-200 m) associated with both modes of variability are simulated. The first mode is characterised by predominant zonal transports. The second mode, mainly associated with meridional geostrophic transports across 5°N, can be described as a low-frequency, asymmetric recharge oscillator.An OGCM forced by atmospheric reanalysis is then used for the 1951-99 period. It proves able to reproduce the modes of variability described above. The model outputs are validated against surface currents, warm water transports, dynamic height and sea level data. The simulated dynamic height includes a partly artificial linear trend. The origin of this trend is identified in the wind forcing. Subtropical cells, which may play an important role in the decadal variability of the tropical Pacific are simulated. The model shows, in agreement with available data, that the increase of the equatorial SST during the last decades could be linked to a decrease of the meridional transports in the pycnocline.; Les deux principaux modes de variabilité interannuelle en niveau de la mer et vent zonal sont mis en évidence à l’aide de données satellitaires sur la période 1993-99 et d’un modèle linéaire forcé par les vents observés sur la période 1964-99. Le premier mode, caractéristique d’ENSO, consiste en un basculement zonal de niveau de la mer autour de la ligne de changement de date, associé à des anomalies de vent équatorial à la même longitude.Le second mode consiste en un basculement méridien de niveau de la mer autour de 5°N, associé à des anomalies de vent de signe opposé dans le nord-ouest et le sud-est du Pacifique tropical. Ce second mode, statistiquement précurseur d’ENSO, semble inclure une composante décennale. Il est particulièrement actif pendant les forts événements El Niño de 1982-83 et 1997-98. Les transports (0-200m) associés à ces deux modes sont calculés à l’aide du modèle. Le premier mode est essentiellement lié à des transports zonaux. Le second mode, qui s’apparente à une version asymétrique et basse fréquence de la théorie de l’oscillateur rechargé, fait intervenir principalement le transport géostrophique à 5°N dans le milieu du bassin.Un OGCM, dont le forçage atmosphérique est issu de réanalyses, est utilisé ensuite sur la période 1951-99. Il reproduit les modes de variabilité décrits précédemment. Le modèle est validé à l’aide de données de courants de surface, transports, hauteur dynamique et niveau de la mer. La hauteur dynamique simulée montre une tendance linéaire en partie artificielle.L’origine de cette tendance est identifiée dans le forçage en vent. Les cellules méridiennes de circulation subtropicale, qui joueraient un rôle important dans la variabilité décennale du Pacifique tropical, sont simulées. Le modèle montre, en accord avec certaines données, que l’augmentation de la SST équatoriale durant les dernières décennies pourrait être liée à la baisse de la convergence des transports dans la pycnocline.

Published
2002

43. CORIOLIS. Rapport d’activités 2016

Author

Pouliquen, Sylvie, Maze, Guillaume, Lebreton, Nathanaele, D'Ortenzio, Fabrizio, Alory, Gaël, Delcroix, Thierry, Bourles, Bernard, Blouch, Pierre, Guinet, Christophe, Gouriou, Yves, Gaillard, Fabienne, Heyndrickx, Céline, Le Menn, Marc, Testor, Pierre, Donato, Vincent, Charria, Guillaume, Carval, Thierry, Reverdin, Gilles, and Emzivat, Gilbert

Subjects
16. Peace & justice
Abstract

Rapport d'activité Coriolis pour l'année 2016 dans le cadre de la convention cadre Coriolis 2014-2020

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