Anomalous summertime CO2 sink in the subpolar Southern Ocean promoted by early 2021 sea ice retreat
Résumé
The physical and biogeochemical processes governing the air–sea CO2 flux in the Southern Ocean are still widely debated. The Southern Ocean Carbon and Heat Impact on Climate cruise in summer 2022 aimed at studying these processes in the Weddell Sea and in its vicinity. A CARbon Interface OCean Atmosphere (CARIOCA) drifting buoy was deployed in January 2022 in the subpolar Southern Ocean, providing hourly surface ocean observations of fCO2 (fugacity of CO2), dissolved oxygen, salinity, temperature, and chlorophyll a fluorescence for 17 months. An underwater glider was piloted with the buoy for the first 6 weeks of the deployment to provide vertical ocean profiles of hydrography and biogeochemistry. These datasets reveal an anomalously strong ocean carbon sink for over 2 months, occurring in the region of Bouvet Island and associated with large plumes of chlorophyll a (Chl a). Based on Lagrangian backward trajectories reconstructed using various surface currents fields, we identified that the water mass reaching the Bouvet Island region originated from the southwest, from the vicinity of the sea ice edge in spring 2021. A strong phytoplankton bloom developed there in November 2021. We propose that it was promoted by early sea ice retreat in 2021 in the Weddell Sea. These waters, depleted in carbon, then traveled to the position of the CARIOCA buoy. The very low values of ocean fCO2, measured by the buoy (down to 310 µatm), are consistent with net community production previously observed during blooms occurring near the sea ice edge, partly compensated by air–sea CO2 flux along the water mass trajectory. Early sea ice retreat might therefore have caused a large CO2 sink farther north than usual in summer 2022, in the Atlantic sector of the subpolar Southern Ocean. Such events might become more frequent in the future as a result of climate change.
Domaines
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Cite 10.17882/100800 Jeu de données Naëck, K., Boutin, J., Beaumont, L., Lourenco, A., & Sallée, J.-B. (2024). CARIOCA observations - SO-CHIC Cruise 2022 [Dataset]. SEANOE. https://doi.org/10.17882/100800
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Cite 10.5281/zenodo.11059426 Jeu de données Swart, S., du Plessis, M., Giddy, I., Edholm, J., Spira, T., Biddle, L., & Rosenthal, H. S. (2024). Dataset from autonomous assets collected during the SO-CHIC field campaign in the Southern Ocean (Version 1) [Dataset]. Zenodo. https://doi.org/10.5281/ZENODO.11059426
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Cite 10.17882/100905 Jeu de données Ward, B., Naëck, K., Boutin, J., Sallée, J.-B., Jacobs, L., & Steiger, N. (2024). TSG observations - SO-CHIC Cruise 2022 [Dataset]. SEANOE. https://doi.org/10.17882/100905
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Cite 10.17882/95314 Jeu de données Steiger, N., Sallée, J., Ward, B., Azevedo, A., Binase, Z., Ten Doeschat, A., Els, H., Hamnca, S., Jacobs, L., Katsoulis, M., Lavanchy, S., Lavis, C., Lourenco, A., Du Plessis, M., Rosenthal, H., Soares, B., & Spira, T. (2022). CTD observation - SO-CHIC Cruise 2022 [Data set]. SEANOE. https://doi.org/10.17882/95314
The S. A. Agulhas II SO-CHIC 2022 cruise CTD data
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Cite 10.24381/cds.adbb2d47 Jeu de données C3S. (2018). ERA5 hourly data on single levels from 1940 to present [Data set]. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). https://doi.org/10.24381/CDS.ADBB2D47
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Cite 10.24381/cds.adbb2d47 Jeu de données C3S. (2018). ERA5 hourly data on single levels from 1940 to present [Data set]. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). https://doi.org/10.24381/CDS.ADBB2D47
A5 atmospheric pressure and wind speed hourly data on single levels from 1940 to present are available on the Copernicus Climate Change Service Climate Data Store
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Cite 10.48670/moi-00021 Jeu de données European Union-Copernicus Marine Service. (2018). Global Ocean Physics Reanalysis [Dataset]. Mercator Ocean International. https://doi.org/10.48670/MOI-00021
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Cite 10.24381/cds.adbb2d47 Jeu de données C3S. (2018). ERA5 hourly data on single levels from 1940 to present [Data set]. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). https://doi.org/10.24381/CDS.ADBB2D47