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4. Variability of Satellite Sea Surface Salinity Under Rainfall

Author

Supply, Alexandre, Boutin, Jacqueline, Reverdin, Gilles, Vergely, Jean-Luc, Bellenger, Hugo, Stoffel, Markus, Series Editor, Cramer, Wolfgang, Advisory Editor, Luterbacher, Urs, Advisory Editor, Toth, F., Advisory Editor, Levizzani, Vincenzo, editor, Kidd, Christopher, editor, Kirschbaum, Dalia B., editor, Kummerow, Christian D., editor, Nakamura, Kenji, editor, and Turk, F. Joseph, editor

Published
2020
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5. Exploring the CO2 fugacity along the east coast of South America aboard the schooner Tara.

Author

Olivier, Léa, Boutin, Jacqueline, Reverdin, Gilles, Hunt, Christopher, Linkowski, Thomas, Chase, Alison, Haentjens, Nils, Junger, Pedro C., Pesant, Stephane, and Vandemark, Douglas

Subjects
REGIONS of freshwater influence, ATMOSPHERIC boundary layer, CHEMICAL formulas, SCHOONERS, FUGACITY
Abstract

The air-sea CO2 flux in the coastal ocean is a key component of the global carbon budget. However, due to the scarcity of data, the many sources and sinks of carbon and their complex interactions in these waters remain poorly understood. In 2021, the Tara schooner collected 14,000 km of CO2 fugacity (fCO2) measurements along the coast of South America, including in the Amazon River-Ocean continuum (https://doi.org/10.5281/zenodo.13790065 , Olivier et al., 2024a). The interactions between the Amazon River and its oceanic plume are complex, and under a combined influence of many processes such as tides and bathymetry. Downstream of the Amazon River plume, the fCO2 is low compared with that of the atmosphere, reaching a minimum of 42 μatm. In the river, fCO2 reaches up to 3000 μatm. South of the estuary, the waters of the North Brazil Current have a fCO2 exceeding 400 μatm. Along the Brazil Current, fCO2 is around 400 μatm and decreases, as does temperature, as the schooner sails away from the equator. Nevertheless, in all the data collected in this coastal environment, salinity varies greatly, and therefore describes best the variability of fCO2. Despite the strong variability and uncertainties in the data, comparison with discrete samples of other carbonate parameters shows that the mean differences (2 µatm) are within the range of uncertainties related to the chemical formula used for the comparison. This data set helps to fill the gap in our knowledge of the behavior of fCO2 in the under-sampled region of the Brazilian coast. [ABSTRACT FROM AUTHOR]

Published
2024
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8. Air-Sea fluxes during the EUREC4A2020 Experiment

Author

Bourras, Denis, Stragapède, Sébastien, Branger, Hubert, Luneau, Chrsitophe, Benjeddou, Saïd, Geyskens, Nicolas, Reverdin, Gilles, Speich, Sabrina, Bourras, Denis, Stragapède, Sébastien, Branger, Hubert, Luneau, Chrsitophe, Benjeddou, Saïd, Geyskens, Nicolas, Reverdin, Gilles, and Speich, Sabrina

Published
2024

9. A synthesis of ocean total alkalinity and dissolved inorganic carbon measurements from 1993 to 2022: the SNAPO-CO2-v1 dataset

Author

Metzl, Nicolas, Fin, Jonathan, Lo Monaco, Claire, Mignon, Claude, Alliouane, Samir, Antoine, David, Bourdin, Guillaume, Boutin, Jacqueline, Bozec, Yann, Conan, Pascal, Coppola, Laurent, Diaz, Frédéric, Douville, Eric, Durrieu de Madron, Xavier, Gattuso, Jean-Pierre, Gazeau, Frédéric, Golbol, Melek, Lansard, Bruno, Lefèvre, Dominique, Lefèvre, Nathalie, Lombard, Fabien, Louanchi, Férial, Merlivat, Liliane, Olivier, Léa, Petrenko, Anne, Petton, Sébastien, Pujo-Pay, Mireille, Rabouille, Christophe, Reverdin, Gilles, Ridame, Céline, Tribollet, Aline, Vellucci, Vincenzo, Wagener, Thibaut, Wimart-Rousseau, Cathy, Metzl, Nicolas, Fin, Jonathan, Lo Monaco, Claire, Mignon, Claude, Alliouane, Samir, Antoine, David, Bourdin, Guillaume, Boutin, Jacqueline, Bozec, Yann, Conan, Pascal, Coppola, Laurent, Diaz, Frédéric, Douville, Eric, Durrieu de Madron, Xavier, Gattuso, Jean-Pierre, Gazeau, Frédéric, Golbol, Melek, Lansard, Bruno, Lefèvre, Dominique, Lefèvre, Nathalie, Lombard, Fabien, Louanchi, Férial, Merlivat, Liliane, Olivier, Léa, Petrenko, Anne, Petton, Sébastien, Pujo-Pay, Mireille, Rabouille, Christophe, Reverdin, Gilles, Ridame, Céline, Tribollet, Aline, Vellucci, Vincenzo, Wagener, Thibaut, and Wimart-Rousseau, Cathy

Abstract

Total alkalinity (AT) and dissolved inorganic carbon (CT) in the oceans are important properties with respect to understanding the ocean carbon cycle and its link to global change (ocean carbon sinks and sources, ocean acidification) and ultimately finding carbon-based solutions or mitigation procedures (marine carbon removal). We present a database of more than 44 400 AT and CT observations along with basic ancillary data (spatiotemporal location, depth, temperature and salinity) from various ocean regions obtained, mainly in the framework of French projects, since 1993. This includes both surface and water column data acquired in the open ocean, coastal zones and in the Mediterranean Sea and either from time series or dedicated one-off cruises. Most AT and CT data in this synthesis were measured from discrete samples using the same closed-cell potentiometric titration calibrated with Certified Reference Material, with an overall accuracy of ±4 µmol kg−1 for both AT and CT. The data are provided in two separate datasets – for the Global Ocean and the Mediterranean Sea (https://doi.org/10.17882/95414, Metzl et al., 2023), respectively – that offer a direct use for regional or global purposes, e.g., AT–salinity relationships, long-term CT estimates, and constraint and validation of diagnostic CT and AT reconstructed fields or ocean carbon and coupled climate–carbon models simulations as well as data derived from Biogeochemical-Argo (BGC-Argo) floats. When associated with other properties, these data can also be used to calculate pH, the fugacity of CO2 (fCO2) and other carbon system properties to derive ocean acidification rates or air–sea CO2 fluxes.

Published
2024
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14. A synthesis of ocean total alkalinity and dissolved inorganic carbon measurements from 1993 to 2022: the SNAPO-CO2-v1 dataset

Author

Metzl, Nicolas, primary, Fin, Jonathan, additional, Lo Monaco, Claire, additional, Mignon, Claude, additional, Alliouane, Samir, additional, Antoine, David, additional, Bourdin, Guillaume, additional, Boutin, Jacqueline, additional, Bozec, Yann, additional, Conan, Pascal, additional, Coppola, Laurent, additional, Diaz, Frédéric, additional, Douville, Eric, additional, Durrieu de Madron, Xavier, additional, Gattuso, Jean-Pierre, additional, Gazeau, Frédéric, additional, Golbol, Melek, additional, Lansard, Bruno, additional, Lefèvre, Dominique, additional, Lefèvre, Nathalie, additional, Lombard, Fabien, additional, Louanchi, Férial, additional, Merlivat, Liliane, additional, Olivier, Léa, additional, Petrenko, Anne, additional, Petton, Sébastien, additional, Pujo-Pay, Mireille, additional, Rabouille, Christophe, additional, Reverdin, Gilles, additional, Ridame, Céline, additional, Tribollet, Aline, additional, Vellucci, Vincenzo, additional, Wagener, Thibaut, additional, and Wimart-Rousseau, Cathy, additional

Published
2024
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15. Anthropogenic CO2, air–sea CO2 fluxes, and acidification in the Southern Ocean: results from a time-series analysis at station OISO-KERFIX (51° S–68° E).

Author

Metzl, Nicolas, Lo Monaco, Claire, Leseurre, Coraline, Ridame, Céline, Reverdin, Gilles, Chau, Thi Tuyet Trang, Chevallier, Frédéric, and Gehlen, Marion

Subjects
OCEAN acidification, ATMOSPHERIC carbon dioxide, ARTIFICIAL neural networks, CARBON dioxide, ATMOSPHERIC boundary layer, SUMMER
Abstract

The temporal variation of the carbonate system, air–sea CO 2 fluxes, and pH is analyzed in the southern Indian Ocean, south of the polar front, based on in situ data obtained from 1985 to 2021 at a fixed station (50°40 ′ S–68°25 ′ E) and results from a neural network model that reconstructs the fugacity of CO 2 (fCO2) and fluxes at monthly scale. Anthropogenic CO 2 (C ant) is estimated in the water column and is detected down to the bottom (1600 m) in 1985, resulting in an aragonite saturation horizon at 600 m that migrated up to 400 m in 2021 due to the accumulation of C ant. At the subsurface, the trend of C ant is estimated at +0.53±0.01 µ mol kg -1 yr -1 with a detectable increase in the trend in recent years. At the surface during austral winter the oceanic fCO2 increased at a rate close to or slightly lower than in the atmosphere. To the contrary, in summer, we observed contrasting fCO2 and dissolved inorganic carbon (C T) trends depending on the decade and emphasizing the role of biological drivers on air–sea CO 2 fluxes and pH inter-annual variability. The regional air–sea CO 2 fluxes evolved from an annual source to the atmosphere of 0.8 molC m -2 yr -1 in 1985 to a sink of -0.5 molC m -2 yr -1 in 2020. Over 1985–2020, the annual pH trend in surface waters of -0.0165±0.0040 per decade was mainly controlled by the accumulation of anthropogenic CO 2 , but the summer pH trends were modulated by natural processes that reduced the acidification rate in the last decade. Using historical data from November 1962, we estimated the long-term trend for fCO2 , C T , and pH, confirming that the progressive acidification was driven by the atmospheric CO 2 increase. In 59 years this led to a diminution of 11 % for both aragonite and calcite saturation state. As atmospheric CO 2 is expected to increase in the future, the pH and carbonate saturation state will decrease at a faster rate than observed in recent years. A projection of future C T concentrations for a high emission scenario (SSP5-8.5) indicates that the surface pH in 2100 would decrease to 7.32 in winter. This is up to -0.86 lower than pre-industrial pH and -0.71 lower than pH observed in 2020. The aragonite undersaturation in surface waters would be reached as soon as 2050 (scenario SSP5-8.5) and 20 years later for a stabilization scenario (SSP2-4.5) with potential impacts on phytoplankton species and higher trophic levels in the rich ecosystems of the Kerguelen Islands area. [ABSTRACT FROM AUTHOR]

Published
2024
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19. Marine Mammals Exploring the Oceans Pole to Pole : A Review of the MEOP Consortium

Author

Treasure, Anne M., Roquet, Fabien, Ansorge, Isabelle J., Bester, Marthán N., Boehme, Lars, Bornemann, Horst, Charrassin, Jean-Benoit, Chevallier, Damien, Costa, Daniel P., Fedak, Mike A., Guinet, Christophe, Hammill, Mike O., Harcourt, Robert G., Hindell, Mark A., Kovacs, Kit M., Lea, Mary-Anne, Lovell, Phil, Lowther, Andrew D., Lydersen, Christian, McIntyre, Trevor, McMahon, Clive R., Muelbert, Mônica M.C., Nicholls, Keith, Picard, Baptiste, Reverdin, Gilles, Trites, Andrew W., Williams, Guy D., and de Bruyn, P.J. Nico

Published
2017

20. A synthesis of SNAPO-CO2 ocean total alkalinity and total dissolved inorganic carbon measurements from 1993 to 2022

Author

Metzl, Nicolas, primary, Fin, Jonathan, additional, Lo Monaco, Claire, additional, Mignon, Claude, additional, Alliouane, Samir, additional, Antoine, David, additional, Bourdin, Guillaume, additional, Boutin, Jacqueline, additional, Bozec, Yann, additional, Conan, Pascal, additional, Coppola, Laurent, additional, Diaz, Frédéric, additional, Douville, Eric, additional, Durrieu de Madron, Xavier, additional, Gattuso, Jean-Pierre, additional, Gazeau, Frédéric, additional, Golbol, Melek, additional, Lansard, Bruno, additional, Lefèvre, Dominique, additional, Lefèvre, Nathalie, additional, Lombard, Fabien, additional, Louanchi, Férial, additional, Merlivat, Liliane, additional, Olivier, Léa, additional, Petrenko, Anne, additional, Petton, Sébastien, additional, Pujo-Pay, Mireille, additional, Rabouille, Christophe, additional, Reverdin, Gilles, additional, Ridame, Céline, additional, Tribollet, Aline, additional, Vellucci, Vincenzo, additional, Wagener, Thibaut, additional, and Wimart-Rousseau, Cathy, additional

Published
2023
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21. Supplementary material to "A synthesis of SNAPO-CO2 ocean total alkalinity and total dissolved inorganic carbon measurements from 1993 to 2022"

Author

Metzl, Nicolas, primary, Fin, Jonathan, additional, Lo Monaco, Claire, additional, Mignon, Claude, additional, Alliouane, Samir, additional, Antoine, David, additional, Bourdin, Guillaume, additional, Boutin, Jacqueline, additional, Bozec, Yann, additional, Conan, Pascal, additional, Coppola, Laurent, additional, Diaz, Frédéric, additional, Douville, Eric, additional, Durrieu de Madron, Xavier, additional, Gattuso, Jean-Pierre, additional, Gazeau, Frédéric, additional, Golbol, Melek, additional, Lansard, Bruno, additional, Lefèvre, Dominique, additional, Lefèvre, Nathalie, additional, Lombard, Fabien, additional, Louanchi, Férial, additional, Merlivat, Liliane, additional, Olivier, Léa, additional, Petrenko, Anne, additional, Petton, Sébastien, additional, Pujo-Pay, Mireille, additional, Rabouille, Christophe, additional, Reverdin, Gilles, additional, Ridame, Céline, additional, Tribollet, Aline, additional, Vellucci, Vincenzo, additional, Wagener, Thibaut, additional, and Wimart-Rousseau, Cathy, additional

Published
2023
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24. Open science resources from the Tara Pacific expedition across coral reef and surface ocean ecosystems

Author

Lombard, Fabien, primary, Bourdin, Guillaume, additional, Pesant, Stéphane, additional, Agostini, Sylvain, additional, Baudena, Alberto, additional, Boissin, Emilie, additional, Cassar, Nicolas, additional, Clampitt, Megan, additional, Conan, Pascal, additional, Da Silva, Ophélie, additional, Dimier, Céline, additional, Douville, Eric, additional, Elineau, Amanda, additional, Fin, Jonathan, additional, Flores, J. Michel, additional, Ghiglione, Jean-François, additional, Hume, Benjamin C. C., additional, Jalabert, Laetitia, additional, John, Seth G., additional, Kelly, Rachel L., additional, Koren, Ilan, additional, Lin, Yajuan, additional, Marie, Dominique, additional, McMinds, Ryan, additional, Mériguet, Zoé, additional, Metzl, Nicolas, additional, Paz-García, David A., additional, Pedrotti, Maria Luiza, additional, Poulain, Julie, additional, Pujo-Pay, Mireille, additional, Ras, Joséphine, additional, Reverdin, Gilles, additional, Romac, Sarah, additional, Rouan, Alice, additional, Röttinger, Eric, additional, Vardi, Assaf, additional, Voolstra, Christian R., additional, Moulin, Clémentine, additional, Iwankow, Guillaume, additional, Banaigs, Bernard, additional, Bowler, Chris, additional, de Vargas, Colomban, additional, Forcioli, Didier, additional, Furla, Paola, additional, Galand, Pierre E., additional, Gilson, Eric, additional, Reynaud, Stéphanie, additional, Sunagawa, Shinichi, additional, Sullivan, Matthew B., additional, Thomas, Olivier P., additional, Troublé, Romain, additional, Thurber, Rebecca Vega, additional, Wincker, Patrick, additional, Zoccola, Didier, additional, Allemand, Denis, additional, Planes, Serge, additional, Boss, Emmanuel, additional, and Gorsky, Gaby, additional

Published
2023
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29. Isotopic evidence for an intensified hydrological cycle in the Indian sector of the Southern Ocean

Author

Hayatte Akhoudas, Camille, Sallée, Jean-baptiste, Reverdin, Gilles, Haumann, Alexander F., Pauthenet, Etienne, Chapman, Christopher, Margirier, Félix, Lo Monaco, Claire, Metzl, Nicolas, Meilland, Julie, Stranne, Christian, Hayatte Akhoudas, Camille, Sallée, Jean-baptiste, Reverdin, Gilles, Haumann, Alexander F., Pauthenet, Etienne, Chapman, Christopher, Margirier, Félix, Lo Monaco, Claire, Metzl, Nicolas, Meilland, Julie, and Stranne, Christian

Abstract

The hydrological cycle is expected to intensify in a warming climate. However, observational evidence of such changes in the Southern Ocean is difficult to obtain due to sparse measurements and a complex superposition of changes in precipitation, sea ice, and glacial meltwater. We here disentangle these signals using a unique dataset of salinity and seawater oxygen isotope observations collected in the Indian sector of the Southern Ocean. Our results show that the atmospheric water cycle has intensified in this region between 1993 and 2021, increasing the salinity in subtropical surface waters by 0.07 g kg-1 per decade, and decreasing it in subpolar surface waters by -0.028 g kg-1 per decade. In the subpolar region, this salinity decrease is countered by a salinity increase of 0.008 g kg-1 per decade from reduced sea ice melt, and enhanced by a salinity decrease of -0.005 g kg-1 per decade from increased glacial melt. These changes extend the growing evidence for an acceleration of the atmospheric water cycle and a melting cryosphere that can be expected from global warming.

Published
2023
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30. Open science resources from the Tara Pacific expedition across coral reef and surface ocean ecosystems

Author

Lombard, Fabien, Bourdin, Guillaume, Pesant, Stéphane, Agostini, Sylvain, Baudena, Alberto, Boissin, Emilie, Cassar, Nicolas, Clampitt, Megan, Conan, Pascal, Da Silva, Ophélie, Dimier, Céline, Douville, Eric, Elineau, Amanda, Fin, Jonathan, Flores, J. Michel, Ghiglione, Jean-françois, Hume, Benjamin C. C., Jalabert, Laetitia, John, Seth G., Kelly, Rachel L., Koren, Ilan, Lin, Yajuan, Marie, Dominique, Mcminds, Ryan, Mériguet, Zoé, Metzl, Nicolas, Paz-garcía, David A., Pedrotti, Maria Luiza, Poulain, Julie, Pujo-pay, Mireille, Ras, Joséphine, Reverdin, Gilles, Romac, Sarah, Rouan, Alice, Röttinger, Eric, Vardi, Assaf, Voolstra, Christian R., Moulin, Clémentine, Iwankow, Guillaume, Banaigs, Bernard, Bowler, Chris, De Vargas, Colomban, Forcioli, Didier, Furla, Paola, Galand, Pierre E., Gilson, Eric, Reynaud, Stéphanie, Sunagawa, Shinichi, Sullivan, Matthew B., Thomas, Olivier P., Troublé, Romain, Thurber, Rebecca Vega, Wincker, Patrick, Zoccola, Didier, Allemand, Denis, Planes, Serge, Boss, Emmanuel, Gorsky, Gaby, Lombard, Fabien, Bourdin, Guillaume, Pesant, Stéphane, Agostini, Sylvain, Baudena, Alberto, Boissin, Emilie, Cassar, Nicolas, Clampitt, Megan, Conan, Pascal, Da Silva, Ophélie, Dimier, Céline, Douville, Eric, Elineau, Amanda, Fin, Jonathan, Flores, J. Michel, Ghiglione, Jean-françois, Hume, Benjamin C. C., Jalabert, Laetitia, John, Seth G., Kelly, Rachel L., Koren, Ilan, Lin, Yajuan, Marie, Dominique, Mcminds, Ryan, Mériguet, Zoé, Metzl, Nicolas, Paz-garcía, David A., Pedrotti, Maria Luiza, Poulain, Julie, Pujo-pay, Mireille, Ras, Joséphine, Reverdin, Gilles, Romac, Sarah, Rouan, Alice, Röttinger, Eric, Vardi, Assaf, Voolstra, Christian R., Moulin, Clémentine, Iwankow, Guillaume, Banaigs, Bernard, Bowler, Chris, De Vargas, Colomban, Forcioli, Didier, Furla, Paola, Galand, Pierre E., Gilson, Eric, Reynaud, Stéphanie, Sunagawa, Shinichi, Sullivan, Matthew B., Thomas, Olivier P., Troublé, Romain, Thurber, Rebecca Vega, Wincker, Patrick, Zoccola, Didier, Allemand, Denis, Planes, Serge, Boss, Emmanuel, and Gorsky, Gaby

Abstract

The Tara Pacific expedition (2016–2018) sampled coral ecosystems around 32 islands in the Pacific Ocean and the ocean surface waters at 249 locations, resulting in the collection of nearly 58 000 samples. The expedition was designed to systematically study warm-water coral reefs and included the collection of corals, fish, plankton, and seawater samples for advanced biogeochemical, molecular, and imaging analysis. Here we provide a complete description of the sampling methodology, and we explain how to explore and access the different datasets generated by the expedition. Environmental context data were obtained from taxonomic registries, gazetteers, almanacs, climatologies, operational biogeochemical models, and satellite observations. The quality of the different environmental measures has been validated not only by various quality control steps, but also through a global analysis allowing the comparison with known environmental large-scale structures. Such publicly released datasets open the perspective to address a wide range of scientific questions.

Published
2023
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31. Lessons learned from the EUREC4A-OA experiment on the impact of ocean small scales on air-sea interactions in the Northwest Tropical Atlantic

Author

Speich, S, Karstensen, J, Reverdin, G, Olivier, L, Fernandez, P, L'Hégaret, P, Coadou, S, Laxenaire, R, Zhang, D, Gentemann, C, Landschutzer, P, Boutin, J, Bellenger, H, Pasquero, C, Meroni, A, Borgnino, M, Acquistapace, C, Bopp, L, Speich, Sabrina, Karstensen, Johannes, Reverdin, Gilles, Olivier, Léa, Fernandez, Pablo, L'Hégaret, Pierre, Coadou, Solange, Laxenaire, Rémi, Zhang, Dongxiao, Gentemann, Chelle, Landschutzer, Peter, Boutin, Jacqueline, Bellenger, Hugo, Pasquero, Claudia, Meroni, Agostino, Borgnino, Matteo, Acquistapace, Claudia, Bopp, Laurent, Speich, S, Karstensen, J, Reverdin, G, Olivier, L, Fernandez, P, L'Hégaret, P, Coadou, S, Laxenaire, R, Zhang, D, Gentemann, C, Landschutzer, P, Boutin, J, Bellenger, H, Pasquero, C, Meroni, A, Borgnino, M, Acquistapace, C, Bopp, L, Speich, Sabrina, Karstensen, Johannes, Reverdin, Gilles, Olivier, Léa, Fernandez, Pablo, L'Hégaret, Pierre, Coadou, Solange, Laxenaire, Rémi, Zhang, Dongxiao, Gentemann, Chelle, Landschutzer, Peter, Boutin, Jacqueline, Bellenger, Hugo, Pasquero, Claudia, Meroni, Agostino, Borgnino, Matteo, Acquistapace, Claudia, and Bopp, Laurent

Published
2023

32. Ocean cross-validated observations from R/Vs L'Atalante, Maria S. Merian, and Meteor and related platforms as part of the EUREC4A-OA/ATOMIC campaign

Author

L'Hégaret, Pierre, Schütte, Florian, Speich, Sabrina, Reverdin, Gilles, Baranowski, Dariusz B., Czeschel, Rena, Fischer, Tim, Foltz, Gregory R., Heywood, Karen J., Krahmann, Gerd, Laxenaire, Rémi, Le Bihan, Caroline, Le Bot, Philippe, Leizour, Stephane, Rollo, Callum, Schlundt, Michael, Siddle, Elizabeth, Subirade, Corentin, Zhang, Dongxiao, Karstensen, Johannes, L'Hégaret, Pierre, Schütte, Florian, Speich, Sabrina, Reverdin, Gilles, Baranowski, Dariusz B., Czeschel, Rena, Fischer, Tim, Foltz, Gregory R., Heywood, Karen J., Krahmann, Gerd, Laxenaire, Rémi, Le Bihan, Caroline, Le Bot, Philippe, Leizour, Stephane, Rollo, Callum, Schlundt, Michael, Siddle, Elizabeth, Subirade, Corentin, Zhang, Dongxiao, and Karstensen, Johannes

Abstract

The northwestern Tropical Atlantic Ocean is a turbulent region, filled with mesoscale eddies and regional currents. In this intense dynamical context, several water masses with thermohaline characteristics of different origins are advected, mixed, and stirred at the surface and at depth. The EUREC4A-OA/ATOMIC experiment that took place in January and February 2020 was dedicated to assessing the processes at play in this region, especially the interaction between the ocean and the atmosphere. For that reason, four oceanographic vessels and different autonomous platforms measured properties near the air–sea interface and acquired thousands of upper-ocean (up to 400–2000 m depth) profiles. However, each device had its own observing capability, varying from deep measurements acquired during vessel stations to shipboard underway near-surface observations and measurements from autonomous and uncrewed systems (such as Saildrones). These observations were undertaken with a specific sampling strategy guided by near-real-time satellite maps and adapted every half day, based on the process that was investigated. These processes were characterized by different spatiotemporal scales, from mesoscale eddies, with diameters exceeding 100 km, to submesoscale filaments of 1 km width. This article describes the datasets gathered from the different devices and how the data were calibrated and validated. In order to ensure an overall consistency, the platforms' datasets are cross-validated using a hierarchy of instruments defined by their own specificity and calibration procedures. This has enabled the quantification of the uncertainty in the measured parameters when different datasets are used together, e.g., https://doi.org/10.17882/92071 (L'Hégaret et al., 2020a).

Published
2023
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33. Anthropogenic CO2, air-sea CO2 fluxes and acidification in the Southern Ocean: results from a time-series analysis at station OISO-KERFIX (51°S-68°E)

Author

Metzl, Nicolas, Lo Monaco, Claire, Leseurre, Coraline, Ridame, Céline, Reverdin, Gilles, Chau, Thi Tuyet Trang, Chevallier, Frédéric, Gehlen, Marion, Metzl, Nicolas, Lo Monaco, Claire, Leseurre, Coraline, Ridame, Céline, Reverdin, Gilles, Chau, Thi Tuyet Trang, Chevallier, Frédéric, and Gehlen, Marion

Abstract

The temporal variation of the carbonate system, air-sea CO2 fluxes and pH is analyzed in the Southern Indian Ocean, south of the Polar Front, based on in-situ data obtained from 1985 to 2021 at a fixed station (50°40’S–68°25’E) and results from a neural network model that reconstructs the fugacity of CO2 (fCO2) and fluxes at monthly scale. Anthropogenic CO2 (Cant) was estimated in the water column and detected down to the bottom (1600 m) in 1985 resulting in an aragonite saturation horizon at 600 m that migrated up to 400 m in 2021 due to the accumulation of Cant. In subsurface, the trend of Cant is estimated at +0.53 (±0.01) µmol.kg-1.yr-1 with a detectable increase in recent years. At the surface during austral winter the oceanic fCO2 increased at a rate close or slightly lower than in the atmosphere. To the contrary, in summer, we observed contrasting fCO2 and dissolved inorganic carbon (CT) trends depending on the decade and emphasizing the role of biological drivers on air-sea CO2 fluxes and pH inter-annual variability. The region moved from an annual source of 0.8 molC.m-2.yr-1 in 1985 to a sink of -0.5 molC.m-2.yr-1 in 2020. In 1985–2020, the annual pH trend in surface of -0.0165 (± 0.0040).decade-1 was mainly controlled by anthropogenic CO2 but the trend was modulated by natural processes. Using historical data from November 1962 we estimated the long-term trend for fCO2, CT and pH confirming that the progressive acidification was driven by atmospheric CO2 increase. In 59 years this leads to a diminution of 11 % for both aragonite and calcite saturation state. As atmospheric CO2 will desperately continue rising in the future, the pH and carbonate saturation state will decrease at a faster rate than observed in recent years. A projection of future CT concentrations for a high emission scenario (SSP5-8.5) indicates that the surface pH in 2100 would decrease to 7.32 in winter. This is up to -0.86 lower than pre-industrial pH and -0.71 lower than pH observed in

Published
2023
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34. Isotopic measurements in water vapor, precipitation, and seawater during EUREC(4)A

Author

Bailey, Adriana, Aemisegger, Franziska, Villiger, Leonie, Los, Sebastian A., Reverdin, Gilles, Melendez, Estefania Quinones, Acquistapace, Claudia, Baranowski, Dariusz B., Bock, Tobias, Bony, Sandrine, Bordsdorff, Tobias, Coffman, Derek, De Szoeke, Simon P., Diekmann, Christopher J., Duetsch, Marina, Ertl, Benjamin, Galewsky, Joseph, Henze, Dean, Makuch, Przemyslaw, Noone, David, Quinn, Patricia K., Roesch, Michael, Schneider, Andreas, Schneider, Matthias, Speich, Sabrina, Stevens, Bjorn, Thompson, Elizabeth J., Bailey, Adriana, Aemisegger, Franziska, Villiger, Leonie, Los, Sebastian A., Reverdin, Gilles, Melendez, Estefania Quinones, Acquistapace, Claudia, Baranowski, Dariusz B., Bock, Tobias, Bony, Sandrine, Bordsdorff, Tobias, Coffman, Derek, De Szoeke, Simon P., Diekmann, Christopher J., Duetsch, Marina, Ertl, Benjamin, Galewsky, Joseph, Henze, Dean, Makuch, Przemyslaw, Noone, David, Quinn, Patricia K., Roesch, Michael, Schneider, Andreas, Schneider, Matthias, Speich, Sabrina, Stevens, Bjorn, and Thompson, Elizabeth J.

Abstract

In early 2020, an international team set out to investigate trade-wind cumulus clouds and their coupling to the large-scale circulation through the field campaign EUREC(4)A: ElUcidating the RolE of Clouds-Circulation Coupling in ClimAte. Focused on the western tropical Atlantic near Barbados, EUREC(4)A deployed a number of innovative observational strategies, including a large network of water isotopic measurements collectively known as EUREC(4)A-iso, to study the tropical shallow convective environment. The goal of the isotopic measurements was to elucidate processes that regulate the hydroclimate state - for example, by identifying moisture sources, quantifying mixing between atmospheric layers, characterizing the microphysics that influence the formation and persistence of clouds and precipitation, and providing an extra constraint in the evaluation of numerical simulations. During the field experiment, researchers deployed seven water vapor isotopic analyzers on two aircraft, on three ships, and at the Barbados Cloud Observatory (BCO). Precipitation was collected for isotopic analysis at the BCO and from aboard four ships. In addition, three ships collected seawater for isotopic analysis. All told, the in situ data span the period 5 January-22 February 2020 and cover the approximate area 6 to 16 degrees N and 50 to 60 degrees W, with water vapor isotope ratios measured from a few meters above sea level to the mid-free troposphere and seawater samples spanning the ocean surface to several kilometers depth.This paper describes the full EUREC(4)A isotopic in situ data collection - providing extensive information about sampling strategies and data uncertainties - and also guides readers to complementary remotely sensed water vapor isotope ratios. All field data have been made publicly available even if they are affected by known biases, as is the case for high-altitude aircraft measurements, one of the two BCO ground-based water vapor time series, and select rain an

Published
2023
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35. EUREC 4 A

Author

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Stevens, Bjorn, Bony, Sandrine, Farrell, David, Ament, Felix, Blyth, Alan, Fairall, Christopher, Karstensen, Johannes, Quinn, Patricia K., Speich, Sabrina, Acquistapace, Claudia, Aemisegger, Franziska, Albright, Anna Lea, Bellenger, Hugo, Bodenschatz, Eberhard, Caesar, Kathy-Ann, Chewitt-Lucas, Rebecca, de Boer, Gijs, Delanoë, Julien, Denby, Leif, Ewald, Florian, Fildier, Benjamin, Forde, Marvin, George, Geet, Gross, Silke, Hagen, Martin, Hausold, Andrea, Heywood, Karen J., Hirsch, Lutz, Jacob, Marek, Jansen, Friedhelm, Kinne, Stefan, Klocke, Daniel, Kölling, Tobias, Konow, Heike, Lothon, Marie, Mohr, Wiebke, Naumann, Ann Kristin, Nuijens, Louise, Olivier, Léa, Pincus, Robert, Pöhlker, Mira, Reverdin, Gilles, Roberts, Gregory, Schnitt, Sabrina, Schulz, Hauke, Siebesma, A. Pier, Stephan, Claudia Christine, Sullivan, Peter, Touzé-Peiffer, Ludovic, Vial, Jessica, Vogel, Raphaela, Zuidema, Paquita, Alexander, Nicola, Alves, Lyndon, Arixi, Sophian, Asmath, Hamish, Bagheri, Gholamhossein, Baier, Katharina, Bailey, Adriana, Baranowski, Dariusz, Baron, Alexandre, Barrau, Sébastien, Barrett, Paul A., Batier, Frédéric, Behrendt, Andreas, Bendinger, Arne, Beucher, Florent, Bigorre, Sebastien, Blades, Edmund, Blossey, Peter, Bock, Olivier, Böing, Steven, Bosser, Pierre, Bourras, Denis, Bouruet-Aubertot, Pascale, Bower, Keith, Branellec, Pierre, Branger, Hubert, Brennek, Michal, Brewer, Alan, Brilouet, Pierre-Etienne, Brügmann, Björn, Buehler, Stefan A., Burke, Elmo, Burton, Ralph, Calmer, Radiance, Canonici, Jean-Christophe, Carton, Xavier, Cato Jr., Gregory, Charles, Jude Andre, Chazette, Patrick, Chen, Yanxu, Chilinski, Michal T., Choularton, Thomas, Chuang, Patrick, Clarke, Shamal, Coe, Hugh, Cornet, Céline, Coutris, Pierre, Couvreux, Fleur, Crewell, Susanne, Cronin, Timothy, Cui, Zhiqiang, Cuypers, Yannis, Daley, Alton, Damerell, Gillian M., Dauhut, Thibaut, Deneke, Hartwig, Desbios, Jean-Philippe, Dörner, Steffen, Donner, Sebastian, Douet, Vincent, Drushka, Kyla, Dütsch, Marina, Ehrlich, André, Emanuel, Kerry, Emmanouilidis, Alexandros, Etienne, Jean-Claude, Etienne-Leblanc, Sheryl, Faure, Ghislain, Feingold, Graham, Ferrero, Luca, Fix, Andreas, Flamant, Cyrille, Flatau, Piotr Jacek, Foltz, Gregory R., Forster, Linda, Furtuna, Iulian, Gadian, Alan, Galewsky, Joseph, Gallagher, Martin, Gallimore, Peter, Gaston, Cassandra, Gentemann, Chelle, Geyskens, Nicolas, Giez, Andreas, Gollop, John, Gouirand, Isabelle, Gourbeyre, Christophe, de Graaf, Dörte, de Groot, Geiske E., Grosz, Robert, Güttler, Johannes, Gutleben, Manuel, Hall, Kashawn, Harris, George, Helfer, Kevin C., Henze, Dean, Herbert, Calvert, Holanda, Bruna, Ibanez-Landeta, Antonio, Intrieri, Janet, Iyer, Suneil, Julien, Fabrice, Kalesse, Heike, Kazil, Jan, Kellman, Alexander, Kidane, Abiel T., Kirchner, Ulrike, Klingebiel, Marcus, Körner, Mareike, Kremper, Leslie Ann, Kretzschmar, Jan, Krüger, Ovid, Kumala, Wojciech, Kurz, Armin, L'Hégaret, Pierre, Labaste, Matthieu, Lachlan-Cope, Tom, Laing, Arlene, Landschützer, Peter, Lang, Theresa, Lange, Diego, Lange, Ingo, Laplace, Clément, Lavik, Gauke, Laxenaire, Rémi, Le Bihan, Caroline, Leandro, Mason, Lefevre, Nathalie, Lena, Marius, Lenschow, Donald, Li, Qiang, Lloyd, Gary, Los, Sebastian, Losi, Niccolò, Lovell, Oscar, Luneau, Christopher, Makuch, Przemyslaw, Malinowski, Szymon, Manta, Gaston, Marinou, Eleni, Marsden, Nicholas, Masson, Sebastien, Maury, Nicolas, Mayer, Bernhard, Mayers-Als, Margarette, Mazel, Christophe, McGeary, Wayne, McWilliams, James C., Mech, Mario, Mehlmann, Melina, Meroni, Agostino Niyonkuru, Mieslinger, Theresa, Minikin, Andreas, Minnett, Peter, Möller, Gregor, Morfa Avalos, Yanmichel, Muller, Caroline, Musat, Ionela, Napoli, Anna, Neuberger, Almuth, Noisel, Christophe, Noone, David, Nordsiek, Freja, Nowak, Jakub L., Oswald, Lothar, Parker, Douglas J., Peck, Carolyn, Person, Renaud, Philippi, Miriam, Plueddemann, Albert, Pöhlker, Christopher, Pörtge, Veronika, Pöschl, Ulrich, Pologne, Lawrence, Posyniak, Michał, Prange, Marc, Quiñones Meléndez, Estefanía, Radtke, Jule, Ramage, Karim, Reimann, Jens, Renault, Lionel, Reus, Klaus, Reyes, Ashford, Ribbe, Joachim, Ringel, Maximilian, Ritschel, Markus, Rocha, Cesar B., Rochetin, Nicolas, Röttenbacher, Johannes, Rollo, Callum, Royer, Haley, Sadoulet, Pauline, Saffin, Leo, Sandiford, Sanola, Sandu, Irina, Schäfer, Michael, Schemann, Vera, Schirmacher, Imke, Schlenczek, Oliver, Schmidt, Jerome, Schröder, Marcel, Schwarzenboeck, Alfons, Sealy, Andrea, Senff, Christoph J., Serikov, Ilya, Shohan, Samkeyat, Siddle, Elizabeth, Smirnov, Alexander, Späth, Florian, Spooner, Branden, Stolla, M. Katharina, Szkółka, Wojciech, de Szoeke, Simon P., Tarot, Stéphane, Tetoni, Eleni, Thompson, Elizabeth, Thomson, Jim, Tomassini, Lorenzo, Totems, Julien, Ubele, Alma Anna, Villiger, Leonie, von Arx, Jan, Wagner, Thomas, Walther, Andi, Webber, Ben, Wendisch, Manfred, Whitehall, Shanice, Wiltshire, Anton, Wing, Allison A., Wirth, Martin, Wiskandt, Jonathan, Wolf, Kevin, Worbes, Ludwig, Wright, Ethan, Wulfmeyer, Volker, Young, Shanea, Zhang, Chidong, Zhang, Dongxiao, Ziemen, Florian, Zinner, Tobias, Zöger, Martin, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Stevens, Bjorn, Bony, Sandrine, Farrell, David, Ament, Felix, Blyth, Alan, Fairall, Christopher, Karstensen, Johannes, Quinn, Patricia K., Speich, Sabrina, Acquistapace, Claudia, Aemisegger, Franziska, Albright, Anna Lea, Bellenger, Hugo, Bodenschatz, Eberhard, Caesar, Kathy-Ann, Chewitt-Lucas, Rebecca, de Boer, Gijs, Delanoë, Julien, Denby, Leif, Ewald, Florian, Fildier, Benjamin, Forde, Marvin, George, Geet, Gross, Silke, Hagen, Martin, Hausold, Andrea, Heywood, Karen J., Hirsch, Lutz, Jacob, Marek, Jansen, Friedhelm, Kinne, Stefan, Klocke, Daniel, Kölling, Tobias, Konow, Heike, Lothon, Marie, Mohr, Wiebke, Naumann, Ann Kristin, Nuijens, Louise, Olivier, Léa, Pincus, Robert, Pöhlker, Mira, Reverdin, Gilles, Roberts, Gregory, Schnitt, Sabrina, Schulz, Hauke, Siebesma, A. Pier, Stephan, Claudia Christine, Sullivan, Peter, Touzé-Peiffer, Ludovic, Vial, Jessica, Vogel, Raphaela, Zuidema, Paquita, Alexander, Nicola, Alves, Lyndon, Arixi, Sophian, Asmath, Hamish, Bagheri, Gholamhossein, Baier, Katharina, Bailey, Adriana, Baranowski, Dariusz, Baron, Alexandre, Barrau, Sébastien, Barrett, Paul A., Batier, Frédéric, Behrendt, Andreas, Bendinger, Arne, Beucher, Florent, Bigorre, Sebastien, Blades, Edmund, Blossey, Peter, Bock, Olivier, Böing, Steven, Bosser, Pierre, Bourras, Denis, Bouruet-Aubertot, Pascale, Bower, Keith, Branellec, Pierre, Branger, Hubert, Brennek, Michal, Brewer, Alan, Brilouet, Pierre-Etienne, Brügmann, Björn, Buehler, Stefan A., Burke, Elmo, Burton, Ralph, Calmer, Radiance, Canonici, Jean-Christophe, Carton, Xavier, Cato Jr., Gregory, Charles, Jude Andre, Chazette, Patrick, Chen, Yanxu, Chilinski, Michal T., Choularton, Thomas, Chuang, Patrick, Clarke, Shamal, Coe, Hugh, Cornet, Céline, Coutris, Pierre, Couvreux, Fleur, Crewell, Susanne, Cronin, Timothy, Cui, Zhiqiang, Cuypers, Yannis, Daley, Alton, Damerell, Gillian M., Dauhut, Thibaut, Deneke, Hartwig, Desbios, Jean-Philippe, Dörner, Steffen, Donner, Sebastian, Douet, Vincent, Drushka, Kyla, Dütsch, Marina, Ehrlich, André, Emanuel, Kerry, Emmanouilidis, Alexandros, Etienne, Jean-Claude, Etienne-Leblanc, Sheryl, Faure, Ghislain, Feingold, Graham, Ferrero, Luca, Fix, Andreas, Flamant, Cyrille, Flatau, Piotr Jacek, Foltz, Gregory R., Forster, Linda, Furtuna, Iulian, Gadian, Alan, Galewsky, Joseph, Gallagher, Martin, Gallimore, Peter, Gaston, Cassandra, Gentemann, Chelle, Geyskens, Nicolas, Giez, Andreas, Gollop, John, Gouirand, Isabelle, Gourbeyre, Christophe, de Graaf, Dörte, de Groot, Geiske E., Grosz, Robert, Güttler, Johannes, Gutleben, Manuel, Hall, Kashawn, Harris, George, Helfer, Kevin C., Henze, Dean, Herbert, Calvert, Holanda, Bruna, Ibanez-Landeta, Antonio, Intrieri, Janet, Iyer, Suneil, Julien, Fabrice, Kalesse, Heike, Kazil, Jan, Kellman, Alexander, Kidane, Abiel T., Kirchner, Ulrike, Klingebiel, Marcus, Körner, Mareike, Kremper, Leslie Ann, Kretzschmar, Jan, Krüger, Ovid, Kumala, Wojciech, Kurz, Armin, L'Hégaret, Pierre, Labaste, Matthieu, Lachlan-Cope, Tom, Laing, Arlene, Landschützer, Peter, Lang, Theresa, Lange, Diego, Lange, Ingo, Laplace, Clément, Lavik, Gauke, Laxenaire, Rémi, Le Bihan, Caroline, Leandro, Mason, Lefevre, Nathalie, Lena, Marius, Lenschow, Donald, Li, Qiang, Lloyd, Gary, Los, Sebastian, Losi, Niccolò, Lovell, Oscar, Luneau, Christopher, Makuch, Przemyslaw, Malinowski, Szymon, Manta, Gaston, Marinou, Eleni, Marsden, Nicholas, Masson, Sebastien, Maury, Nicolas, Mayer, Bernhard, Mayers-Als, Margarette, Mazel, Christophe, McGeary, Wayne, McWilliams, James C., Mech, Mario, Mehlmann, Melina, Meroni, Agostino Niyonkuru, Mieslinger, Theresa, Minikin, Andreas, Minnett, Peter, Möller, Gregor, Morfa Avalos, Yanmichel, Muller, Caroline, Musat, Ionela, Napoli, Anna, Neuberger, Almuth, Noisel, Christophe, Noone, David, Nordsiek, Freja, Nowak, Jakub L., Oswald, Lothar, Parker, Douglas J., Peck, Carolyn, Person, Renaud, Philippi, Miriam, Plueddemann, Albert, Pöhlker, Christopher, Pörtge, Veronika, Pöschl, Ulrich, Pologne, Lawrence, Posyniak, Michał, Prange, Marc, Quiñones Meléndez, Estefanía, Radtke, Jule, Ramage, Karim, Reimann, Jens, Renault, Lionel, Reus, Klaus, Reyes, Ashford, Ribbe, Joachim, Ringel, Maximilian, Ritschel, Markus, Rocha, Cesar B., Rochetin, Nicolas, Röttenbacher, Johannes, Rollo, Callum, Royer, Haley, Sadoulet, Pauline, Saffin, Leo, Sandiford, Sanola, Sandu, Irina, Schäfer, Michael, Schemann, Vera, Schirmacher, Imke, Schlenczek, Oliver, Schmidt, Jerome, Schröder, Marcel, Schwarzenboeck, Alfons, Sealy, Andrea, Senff, Christoph J., Serikov, Ilya, Shohan, Samkeyat, Siddle, Elizabeth, Smirnov, Alexander, Späth, Florian, Spooner, Branden, Stolla, M. Katharina, Szkółka, Wojciech, de Szoeke, Simon P., Tarot, Stéphane, Tetoni, Eleni, Thompson, Elizabeth, Thomson, Jim, Tomassini, Lorenzo, Totems, Julien, Ubele, Alma Anna, Villiger, Leonie, von Arx, Jan, Wagner, Thomas, Walther, Andi, Webber, Ben, Wendisch, Manfred, Whitehall, Shanice, Wiltshire, Anton, Wing, Allison A., Wirth, Martin, Wiskandt, Jonathan, Wolf, Kevin, Worbes, Ludwig, Wright, Ethan, Wulfmeyer, Volker, Young, Shanea, Zhang, Chidong, Zhang, Dongxiao, Ziemen, Florian, Zinner, Tobias, and Zöger, Martin

Abstract

Abstract. The science guiding the EUREC4A campaign and its measurements is presented. EUREC4A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC4A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC4A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC4A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement.

Published
2023

36. Anthropogenic CO2, air-sea CO2 fluxes and acidification in the Southern Ocean: results from a time-series analysis at station OISO-KERFIX (51°S-68°E).

Author

Metzl, Nicolas, Monaco, Claire Lo, Leseurre, Coraline, Ridame, Céline, Reverdin, Gilles, Chau, Thi Tuyet Trang, Chevallier, Frédéric, and Gehlen, Marion

Subjects
OCEAN acidification, ATMOSPHERIC boundary layer, ARAGONITE, FOOD chains, OCEAN-atmosphere interaction
Abstract

The temporal variation of the carbonate system, air-sea CO2 fluxes and pH is analyzed in the Southern Indian Ocean, south of the Polar Front, based on in-situ data obtained from 1985 to 2021 at a fixed station (50°40'S–68°25'E) and results from a neural network model that reconstructs the fugacity of CO2 (fCO2) and fluxes at monthly scale. Anthropogenic CO2 (Cant) was estimated in the water column and detected down to the bottom (1600 m) in 1985 resulting in an aragonite saturation horizon at 600 m that migrated up to 400 m in 2021 due to the accumulation of Cant. In subsurface, the trend of Cant is estimated at +0.53 (±0.01) µmol.kg-1.yr-1 with a detectable increase in recent years. At the surface during austral winter the oceanic fCO2 increased at a rate close or slightly lower than in the atmosphere. To the contrary, in summer, we observed contrasting fCO2 and dissolved inorganic carbon (CT) trends depending on the decade and emphasizing the role of biological drivers on air-sea CO2 fluxes and pH inter-annual variability. The region moved from an annual source of 0.8 molC.m-2.yr-1 in 1985 to a sink of -0.5 molC.m-2.yr-1 in 2020. In 1985–2020, the annual pH trend in surface of -0.0165 (± 0.0040).decade-1 was mainly controlled by anthropogenic CO2 but the trend was modulated by natural processes. Using historical data from November 1962 we estimated the long-term trend for fCO2, CT and pH confirming that the progressive acidification was driven by atmospheric CO2 increase. In 59 years this leads to a diminution of 11 % for both aragonite and calcite saturation state. As atmospheric CO2 will desperately continue rising in the future, the pH and carbonate saturation state will decrease at a faster rate than observed in recent years. A projection of future CT concentrations for a high emission scenario (SSP5-8.5) indicates that the surface pH in 2100 would decrease to 7.32 in winter. This is up to -0.86 lower than pre-industrial pH and -0.71 lower than pH observed in 2020. The aragonite under-saturation in surface waters would be reached as soon as 2050 (scenario SSP5-8.5) and 20 years later for a stabilization scenario (SSP2-4.5) with potential impacts on phytoplankton species and higher trophic levels in the rich ecosystems of the Kerguelen Island area. [ABSTRACT FROM AUTHOR]

Published
2023
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37. Ocean cross-validated observations from R/Vs L'Atalante, Maria S. Merian, and Meteor and related platforms as part of the EUREC4A-OA/ATOMIC campaign

Author

L'Hégaret, Pierre, primary, Schütte, Florian, additional, Speich, Sabrina, additional, Reverdin, Gilles, additional, Baranowski, Dariusz B., additional, Czeschel, Rena, additional, Fischer, Tim, additional, Foltz, Gregory R., additional, Heywood, Karen J., additional, Krahmann, Gerd, additional, Laxenaire, Rémi, additional, Le Bihan, Caroline, additional, Le Bot, Philippe, additional, Leizour, Stéphane, additional, Rollo, Callum, additional, Schlundt, Michael, additional, Siddle, Elizabeth, additional, Subirade, Corentin, additional, Zhang, Dongxiao, additional, and Karstensen, Johannes, additional

Published
2023
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38. Lessons learned from the EUREC4A-OA experiment on the impact of ocean small scales on air-sea interactions in the Northwest Tropical Atlantic

Author

Speich, Sabrina, primary, Karstensen, Johannes, additional, Reverdin, Gilles, additional, Olivier, Léa, additional, Fernandez, Pablo, additional, L'Hégaret, Pierre, additional, Coadou, Solange, additional, Laxenaire, Rémi, additional, Zhang, Dongxiao, additional, Gentemann, Chelle, additional, Landschutzer, Peter, additional, Boutin, Jacqueline, additional, Bellenger, Hugo, additional, Pasquero, Claudia, additional, Meroni, Agostino, additional, Borgnino, Matteo, additional, Acquistapace, Claudia, additional, and Bopp, Laurent, additional

Published
2023
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41. Isotopic measurements in water vapor, precipitation, and seawater during EUREC4A

Author

Bailey, Adriana, primary, Aemisegger, Franziska, additional, Villiger, Leonie, additional, Los, Sebastian A., additional, Reverdin, Gilles, additional, Quiñones Meléndez, Estefanía, additional, Acquistapace, Claudia, additional, Baranowski, Dariusz B., additional, Böck, Tobias, additional, Bony, Sandrine, additional, Bordsdorff, Tobias, additional, Coffman, Derek, additional, de Szoeke, Simon P., additional, Diekmann, Christopher J., additional, Dütsch, Marina, additional, Ertl, Benjamin, additional, Galewsky, Joseph, additional, Henze, Dean, additional, Makuch, Przemyslaw, additional, Noone, David, additional, Quinn, Patricia K., additional, Rösch, Michael, additional, Schneider, Andreas, additional, Schneider, Matthias, additional, Speich, Sabrina, additional, Stevens, Bjorn, additional, and Thompson, Elizabeth J., additional

Published
2023
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42. Ocean cross-validated observations from the R/Vs L'Atalante, Maria S. Merian and Meteor and related platforms as part of the EUREC4A-OA/ATOMIC campaign

Author

L'Hégaret, Pierre, primary, Schütte, Florian, additional, Speich, Sabrina, additional, Reverdin, Gilles, additional, Baranowski, Dariusz B., additional, Czeschel, Rena, additional, Fischer, Tim, additional, Foltz, Gregory R., additional, Heywood, Karen J., additional, Krahmann, Gerd, additional, Laxenaire, Rémi, additional, Le Bihan, Caroline, additional, Le Bot, Philippe, additional, Leizour, Stéphane, additional, Rollo, Callum, additional, Schlundt, Michael, additional, Siddle, Elizabeth, additional, Subirade, Corentin, additional, Zhang, Dongxiao, additional, and Karstensen, Johannes, additional

Published
2022
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45. Isotopic evidence for an intensified hydrological cycle in the Indian sector of the Southern Ocean

Author

Akhoudas, Camille Hayatte, primary, Sallée, Jean-Baptiste, additional, Reverdin, Gilles, additional, Haumann, F. Alexander, additional, Pauthenet, Etienne, additional, Chapman, Christopher, additional, Margirier, Félix, additional, Monaco, Claire Lo, additional, Metzl, Nicolas, additional, Meilland, Julie, additional, and Stranne, Christian, additional

Published
2022
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49. Wintertime process study of the North Brazil Current rings reveals the region as a larger sink for CO2 than expected

Author

Olivier, Léa, Boutin, Jacqueline, Reverdin, Gilles, Lefèvre, Nathalie, Landschützer, Peter, Speich, Sabrina, Karstensen, Johannes, Ritschel, Markus, and Wanninkhof, Rik

Abstract

The North Brazil Current (NBC) flows northward across the Equator, passes the mouth of the Amazon River, and forms large oceanic eddies near 8° N. We investigate the processes driving the variability of air-sea CO2 fluxes at different scales in early 2020 in the region [50° W–59° W–5° N–16° N]. This region is a pathway between the equatorial and North Atlantic Ocean and was surveyed during the EUREC4A-OA/ATOMIC campaign. In-situ surface fugacity of CO2 (fCO2), salinity and temperature combined with maps of satellite salinity, chlorophyll-a and temperature highlight contrasting properties in the region. In February 2020, the area is a CO2 sink (−1.7 TgC.month−1), previously underestimated by a factor 10. The NBC rings transport saline and high fCO2 water indicative of their equatorial origins and are a small source of CO2 at regional scale. Their main impact on the variability of biogeochemical parameters is through the filaments they entrain into the open ocean. During the campaign, a nutrient-rich freshwater plume from the Amazon River is entrained from the shelf up to 12° N and caused a phytoplankton bloom leading to a significant carbon drawdown (~20 % of the total sink). On the other hand, saltier filaments of shelf water rich in detrital material act as strong local sources of CO2. Spatial distribution of fCO2 is therefore strongly influenced by ocean dynamics south of 12° N. The less variable North Atlantic subtropical water extends from Barbados northward. They represent ~60 % of the total sink due to their lower temperature associated with winter cooling and strong winds.

Published
2022

50. Summer trends and drivers of sea surface fCO2 and pH changes observed in the southern Indian Ocean over the last two decades (1998–2019)

Author

Leseurre, Coraline, Lo Monaco, Claire, Reverdin, Gilles, Metzl, Nicolas, Fin, Jonathan, Mignon, Claude, and Benito, Léa

Abstract

The decadal changes of the fugacity of CO2 (fCO2) and pH in surface waters are investigated in the Southern Indian Ocean (45° S–57° S) using repeated summer observations, including measurements of fCO2, total alkalinity (AT) and total carbon (CT) collected over the period 1998–2019 in the frame of the French monitoring program OISO. We used three datasets (underway fCO2, underway AT-CT and station AT-CT) to evaluate the trends of fCO2 and pH and their drivers, including the accumulation of anthropogenic CO2 (Cant). The study region is separated into three domains based on the frontal system and biogeochemical characteristics: (i) High Nutrients Low Chlorophyll (HNLC) waters in the Polar Front Zone (PFZ), (ii) HNLC waters south of the Polar Front (PF) and (iii) the highly productive zones in fertilized waters near Crozet and Kerguelen Islands. Almost everywhere, we obtained similar trends in surface fCO2 and pH using the fCO2 or AT-CT datasets. Over the period 1998–2019, we observed an increase in surface fCO2 and a decrease in pH ranging from +1.0 to +4.0 µatm yr−1 and from −0.0015 to −0.0043 yr−1, respectively. South of the PF, the fCO2 trend is close to the atmospheric CO2 rise (+2.0 µatm yr−1) and the decrease in pH is in the range of the mean trend for the global ocean (around −0.0020 yr−1); these trends are driven by the warming of surface waters (up to +0.04 °C yr−1) and the increase in CT, mainly due to the accumulation of Cant (around +0.6 µmol kg−1 yr−1). In the PFZ, our data show slower fCO2 and pH trends (around +1.3 µatm yr−1 and −0.0013 yr−1, respectively) associated with an increase in AT (around +0.4 µmol kg−1 yr−1) that limited the impact of a more rapid accumulation of Cant north of the PF (up to +1.1 µmol kg−1 yr−1). In the fertilized waters near Crozet and Kerguelen Islands, fCO2 increased and pH decreased faster than in the other domains, between +2.2 and +4.0 µatm yr−1 and between −0.0023 yr−1 and −0.0043 yr−1. The fastest trends of fCO2 and pH are found around Kerguelen Island north and south of the PF. These trends result from both a significant warming (up to +0.07 °C yr−1) and a rapid increase in CT (up to +1.4 µmol kg−1 yr−1), mainly explained by the uptake of Cant. Our data also show rapid changes on short periods and a relative stability of both fCO2 and pH in recent years at several locations both north and south of the PF, which leaves many open questions, notably the tipping point for the saturation state of carbonate minerals that remains highly uncertain. This highlights the need to maintain observations on the long-term in order to explore how the carbonate system will evolve in this region in the next decades.

Published
2022

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