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1. 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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2. 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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4. 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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5. 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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6. A synthesis of SNAPO-CO2 ocean total alkalinity and total dissolved inorganic carbon measurements from 1993 to 2022.

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, de Madron, Xavier Durrieu, Gattuso, Jean-Pierre, Gazeau, Frédéric, Golbol, Melek, Lansard, Bruno, Lefèvre, Dominique, and Lefèvre, Nathalie

Subjects
CARBON cycle, OCEAN, ALKALINITY, OCEAN acidification, POTENTIOMETRY, COASTS
Abstract

Total alkalinity (AT) and total dissolved inorganic carbon (CT) in the oceans are important properties to understand the ocean carbon cycle and its link with climate change (ocean carbon sinks and sources) or global change (ocean acidification). We present a data-base of more than 44 400 AT and CT observations in various ocean regions obtained since 1993 mainly in the frame of French projects. This includes both surface and water columns data acquired in open oceans, coastal zones and in the Mediterranean Sea and either from time-series or punctual 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. Given the lack of observations in the Indian and Southern Oceans, we added sea surface underway AT and CT data obtained in 1998-2018 in the frame of OISO cruises and in 2019 during the CLIM-EPARSES cruise measured onboard using the same technique. Separate datasets for the global ocean, and for the Mediterranean Sea are provided in a single format (https://doi.org/10.17882/95414, Metzl et al., 2023) that offers a direct use for regional or global purposes, e.g. AT/Salinity relationships, long-term CT estimates, constraint and validation of diagnostics CT-AT reconstructed fields or ocean carbon and coupled climate/carbon models simulations, as well as data derived from BG-ARGO floats. When associated with other properties, these data can also be used to calculate pH, fugacity of CO2 (fCO2) and other carbon systems properties to derive ocean acidification rates or air-sea CO2 fluxes. [ABSTRACT FROM AUTHOR]

Published
2023
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8. 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

9. The impact of the South-East Madagascar bloom on the oceanic CO2 sink

Author

Metzl, Nicolas, Lo Monaco, Claire, Leseurre, Coraline, Ridame, Céline, Fin, Jonathan, Mignon, Claude, Gehlen, Marion, Chau, Thi Tuyet Trang, Metzl, Nicolas, Lo Monaco, Claire, Leseurre, Coraline, Ridame, Céline, Fin, Jonathan, Mignon, Claude, Gehlen, Marion, and Chau, Thi Tuyet Trang

Abstract

We described new sea surface CO2 observations in the southwestern Indian Ocean obtained in January 2020 when a strong bloom event occurred south-east of Madagascar and extended eastward in the oligotrophic Indian Ocean subtropical domain. Compared to previous years (1991–2019) we observed very low fCO2 and dissolved inorganic carbon concentrations (CT) in austral summer 2020, indicative of a biologically driven process. In the bloom the anomaly of fCO2 and CT reached respectively −33 µatm and −42 µmol.kg-1 whereas no change is observed for alkalinity (AT). In January 2020 we estimated a local maximum of air-sea CO2 flux at 27° S of −6.9 mmol.m-2.d-1 (ocean sink) and −4.3 mmol.m-2.d-1 when averaging the flux in the band 26–30° S. In the domain 25–30° S/50–60° E we estimated that the bloom led to a regional carbon uptake of about −1 TgC.month-1 in January 2020 whereas this region was previously recognized as an ocean CO2 source or near equilibrium during this season. Using a neural network approach that reconstructs the monthly fCO2 fields we estimated that when the bloom was at peak in December 2019 the CO2 sink reached −3.1 (±1.0) mmol.m-2.d-1 in the band 25–30° S, i.e. the model captured the impact of the bloom. Integrated in the domain restricted to 25–30° S/50–60° E the region was a CO2 sink in December 2019 of −0.8 TgC.month-1 compared to a CO2 source of +0.12 (± 0.10) TgC.month-1 in December when averaged over the period 1996–2018. Consequently in 2019 this region was a stronger CO2 annual sink of −8.8 TgC.yr-1 compared to −7.0 (±0.5) TgC.yr-1 averaged over 1996–2018. In austral summer 2019/2020, the bloom was likely controlled by relatively deep mixed-layer depth during preceding winter (July–September 2019) that would supply macro and/or micro-nutrients as iron to the surface layer to promote the bloom that started in November 2019 in two large rings in the Madagascar Basin. Based on measurements in January 2020, we observed relatively high N2 fixation rates

Published
2022
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11. 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, Benito, Léa, Cycles biogéochimiques marins : processus et perturbations (CYBIOM), 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)-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)), 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), Processus et interactions de fine échelle océanique (PROTEO), and LEFE-INSU programme KER-Trend

Subjects
[SDE.MCG]Environmental Sciences/Global Changes
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.

Published
2022

17. The impact of the South-East Madagascar bloom on the oceanic CO2 sink

Author

Metzl, Nicolas, Lo Monaco, Claire, Leseurre, Coraline, Ridame, Céline, Fin, Jonathan, Mignon, Claude, Gehlen, Marion, Chau, Thi Tuyet Trang, Metzl, Nicolas, Lo Monaco, Claire, Leseurre, Coraline, Ridame, Céline, Fin, Jonathan, Mignon, Claude, Gehlen, Marion, and Chau, Thi Tuyet Trang

Abstract

We described new sea surface CO2 observations in the southwestern Indian Ocean obtained in January 2020 when a strong bloom event occurred south-east of Madagascar and extended eastward in the oligotrophic Indian Ocean subtropical domain. Compared to previous years (1991–2019) we observed very low fCO2 and dissolved inorganic carbon concentrations (CT) in austral summer 2020, indicative of a biologically driven process. In the bloom the anomaly of fCO2 and CT reached respectively −33 µatm and −42 µmol.kg-1 whereas no change is observed for alkalinity (AT). In January 2020 we estimated a local maximum of air-sea CO2 flux at 27° S of −6.9 mmol.m-2.d-1 (ocean sink) and −4.3 mmol.m-2.d-1 when averaging the flux in the band 26–30° S. In the domain 25–30° S/50–60° E we estimated that the bloom led to a regional carbon uptake of about −1 TgC.month-1 in January 2020 whereas this region was previously recognized as an ocean CO2 source or near equilibrium during this season. Using a neural network approach that reconstructs the monthly fCO2 fields we estimated that when the bloom was at peak in December 2019 the CO2 sink reached −3.1 (±1.0) mmol.m-2.d-1 in the band 25–30° S, i.e. the model captured the impact of the bloom. Integrated in the domain restricted to 25–30° S/50–60° E the region was a CO2 sink in December 2019 of −0.8 TgC.month-1 compared to a CO2 source of +0.12 (± 0.10) TgC.month-1 in December when averaged over the period 1996–2018. Consequently in 2019 this region was a stronger CO2 annual sink of −8.8 TgC.yr-1 compared to −7.0 (±0.5) TgC.yr-1 averaged over 1996–2018. In austral summer 2019/2020, the bloom was likely controlled by relatively deep mixed-layer depth during preceding winter (July–September 2019) that would supply macro and/or micro-nutrients as iron to the surface layer to promote the bloom that started in November 2019 in two large rings in the Madagascar Basin. Based on measurements in January 2020, we observed relatively high N2 fixation rates

Published
2021
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20. Variability and stability of anthropogenic CO2 in Antarctic Bottom Water observed in the Indian sector of the Southern Ocean, 1978–2018

Author

Mahieu, Léo, Monaco, Claire, Metzl, Nicolas, Fin, Jonathan, Mignon, Claude, School of Environmental Sciences [Liverpool], University of Liverpool, Cycles biogéochimiques marins : processus et perturbations (CYBIOM), 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)-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)), 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), European Project: GOCE-511176-1, European Project: 264879,EC:FP7:ENV,FP7-ENV-2010,CARBOCHANGE(2011), 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)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), 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)-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)

Subjects
lcsh:GE1-350, TheoryofComputation_MATHEMATICALLOGICANDFORMALLANGUAGES, lcsh:G, [SDE.MCG]Environmental Sciences/Global Changes, lcsh:Geography. Anthropology. Recreation, lcsh:Environmental sciences
Abstract

Antarctic Bottom Water (AABW) is known as a long-term sink for anthropogenic CO2 (Cant), but the sink is hardly quantified because of the scarcity of observations, specifically at an interannual scale. We present in this paper an original dataset combining 40 years of carbonate system observations in the Indian sector of the Southern Ocean (Enderby Basin) to evaluate and interpret the interannual variability of Cant in the AABW. This investigation is based on regular observations collected at the same location (63∘ E–56.5∘ S) in the framework of the French observatory OISO from 1998 to 2018 extended by GEOSECS and INDIGO observations (1978, 1985 and 1987). At this location the main sources of AABW sampled is the low-salinity Cape Darnley Bottom Water (CDBW) and the Weddell Sea Deep Water (WSDW). Our calculations reveal that Cant concentrations increased significantly in the AABW, from an average concentration of 7 µmol kg−1 calculated for the period 1978–1987 to an average concentration of 13 µmol kg−1 for the period 2010–2018. This is comparable to previous estimates in other Southern Ocean (SO) basins, with the exception of bottom water close to formation sites where Cant concentrations are about twice as large. Our analysis shows that total carbon (CT) and Cant increasing rates in the AABW are about the same over the period 1978–2018, and we conclude that the long-term change in CT is mainly due to the uptake of Cant in the different formation regions. This is, however, modulated by significant interannual to multi-annual variability associated with variations in hydrographic (potential temperature, Θ; salinity, S) and biogeochemical (CT; total alkalinity, AT; dissolved oxygen, O2) properties. A surprising result is the apparent stability of Cant concentrations in recent years despite the increase in CT and the gradual acceleration of atmospheric CO2. The interannual variability at play in AABW needs to be carefully considered in the extrapolated estimation of Cant sequestration based on sparse observations over several years.

Published
2020

21. 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, Monaco, Claire Lo, Reverdin, Gilles, Metzl, Nicolas, Fin, Jonathan, Mignon, Claude, and Benito, Léa

Subjects
ATMOSPHERIC carbon dioxide, WATERFRONTS, CARBONATE minerals, CARBON dioxide, OPEN-ended questions, OCEAN
Abstract

10 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 15 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 20 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 25 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 30 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. [ABSTRACT FROM AUTHOR]

Published
2022
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23. The impact of the South-East Madagascar bloom on the oceanic CO2 sink.

Author

Metzl, Nicolas, Lo Monaco, Claire, Leseurre, Coraline, Ridame, Céline, Fin, Jonathan, Mignon, Claude, Gehlen, Marion, and Thi Tuyet Trang Chau

Subjects
ATMOSPHERIC carbon dioxide, ANTS, CARBON dioxide in water, SEAWATER salinity, CARBON dioxide in seawater, ALGAL blooms, CALIBRATION gases
Abstract

We described new sea surface CO2 observations in the southwestern Indian Ocean obtained in January 2020 when a strong bloom event occurred south-east of Madagascar and extended eastward in the oligotrophic Indian Ocean subtropical domain. Compared to previous years (1991-2019) we observed very low fCO2 and dissolved inorganic carbon concentrations (CT) in austral summer 2020, indicative of a biologically driven process. In the bloom the anomaly of fCO2 and C[sub T] reached respectively -33 µatm and -42 µmol.kg-1 whereas no change is observed for alkalinity (AT). In January 2020 we estimated a local maximum of air-sea CO2 flux at 27°S of -6.9 mmol.m-2.d-1 (ocean sink) and -4.3 mmol.m[sup -2].d[sup -1] when averaging the flux in the band 26-30°S. In the domain 25-30°S/50-60°E we estimated that the bloom led to a regional carbon uptake of about -1 TgC.month-1 in January 2020 whereas this region was previously recognized as an ocean CO2 source or near equilibrium during this season. Using a neural network approach that reconstructs the monthly fCO2 fields we estimated that when the bloom was at peak in December 2019 the CO2 sink reached -3.1 (±1.0) mmol.m[sup -2].d[sup -1] in the band 25-30°S, i.e. the model captured the impact of the bloom. Integrated in the domain restricted to 25-30°S/50-60°E the region was a CO2 sink in December 2019 of -0.8 TgC.month[sup -1] compared to a CO2 source of +0.12 (± 0.10) TgC.month-1 in December when averaged over the period 1996-2018. Consequently in 2019 this region was a stronger CO2 annual sink of -8.8 TgC.yr-1 compared to -7.0 (±0.5) TgC.yr-1 averaged over 1996-2018. In austral summer 2019/2020, the bloom was likely controlled by relatively deep mixed-layer depth during preceding winter (July-September 2019) that would supply macro and/or micro-nutrients as iron to the surface layer to promote the bloom that started in November 2019 in two large rings in the Madagascar Basin. Based on measurements in January 2020, we observed relatively high N2 fixation rates (up to 18 nmol N.L-1.d-1) suggesting that diazotrophs could play a role on the bloom in the nutrient depleted waters. The bloom event in austral summer 2020, along with the new carbonate system observations, represents a benchmark case for complex biogeochemical model sensitivity studies (including N[sub 2]-fixation process and iron supplies) for a better understanding on the origin and termination of this still "mysterious" sporadic bloom and its impact on ocean carbon uptake in the future. [ABSTRACT FROM AUTHOR]

Published
2021
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26. CO2 monitoring in the South-West Indian Ocean over the last three decades

Author

Metzl, Nicolas, Lo Monaco, Claire, Mignon, Claude, Équipe CO2 (E-CO2), 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), 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
2017

27. Variability and stability of anthropogenic CO2 in Antarctic Bottom Waters observed in the Indian sector of the Southern Ocean, 1978-2018.

Author

Mahieu, Léo, Monaco, Claire Lo, Metzl, Nicolas, Fin, Jonathan, and Mignon, Claude

Subjects
OCEAN, CHEMICAL processes, SEAWATER, WATER, SEQUESTRATION (Chemistry), DISPERSION (Atmospheric chemistry)
Abstract

Antarctic bottom waters (AABWs) are known as a long term sink for anthropogenic CO2 (Cant) but is hardly quantified because of the scarcity of the observations, specifically at an interannual scale. We present in this manuscript an original dataset combining 40 years of carbonate system observations in the Indian sector of the Southern Ocean (Enderby Basin) to evaluate and interpret the interannual variability of Cant in the AABW. This investigation is based on regular observations collected at the same location (63° E/56.5° S) in the frame of the French observatory OISO from 1998 to 2018 extended by GEOSECS and INDIGO observations (1978, 1985 and 1987). At this location the main sources of AABW sampled is the fresh and younger Cape Darnley bottom water (CDBW) and the Weddell Sea deep water (WSDW). Our calculations reveal that Cant concentrations increased significantly in AABW, from about + 7 µmol kg-1 in 1978-1987 to + 13 µmol kg-1 in 2010-2018. This is comparable to previous estimates in other SO basins, with the exception of bottom waters close to their formation sites where Cant concentrations are about twice as large. Our analysis shows that the CT and Cant increasing rates in AABW are about the same over the period 1978-2018, and we conclude that the long-term change in CT is mainly due to the uptake of anthropogenic CO2 in the different formation regions. This is however modulated by significant interannual to pluriannual variability associated with variations in hydrological (…, S) and biogeochemical (CT, AT, O2) properties. A surprising result is the apparent stability of Cant concentrations in recent years despite the increase in CT and the gradual acceleration of atmospheric CO2. The Cant sequestration by AABWs is more variable than expected and depends on a complex combination of physical, chemical and biological processes at the formation sites and during the transit of the different AABWs. The interannual variability at play in AABW needs to be carefully considered on the extrapolated estimation of Cant sequestration based on sparse observations over several years. [ABSTRACT FROM AUTHOR]

Published
2020
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28. Long-term CO2 monitoring in the Southern Indian Ocean. 'Sustained ocean observing for the next decade', GAIC2015, Go-Ship/Argo/IOCCP

Author

Lo Monaco, Claire, Metzl, Nicolas, Gomez, R., Mignon, Claude, Pierre, Catherine, Racapé, Virginie, Équipe CO2 (E-CO2), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), 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), 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)), 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), Biogéochimie-Traceurs-Paléoclimat (BTP), 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), 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)-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))

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

International audience

Published
2015

30. The first direct probing of porosity on supported mesoporous silica thin films through hyperpolarised 129Xe NMR

Author

Nossov, Andrei, Haddad, Elias, Guenneau, Flavien, Mignon, Claude, Gédéon, Antoine, Grosso, David, Babonneau, Florence, Bonhomme, Christian, and Sanchez, Clément

Abstract

The continuous flow hyperpolarised (HP) 129Xe NMR technique has been used for the first time on mesoporous silica thin films. This study demonstrates the possibility of recording information about the porosity of a very small quantity of materials and the high sensitivity of the NMR response to pore size and pore functionality.

Published
2002

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