Observing Antarctic Bottom Water in the Southern Ocean

• Published in: Frontiers in Marine Science
• Main Authors: Silvano, Alessandro, Purkey, Sarah, Gordon, Arnold, Castagno, Pasquale, Stewart, Andrew, Rintoul, Stephen, Foppert, Annie, Gunn, Kathryn, Herraiz-Borreguero, Laura, Aoki, Shigeru, Nakayama, Yoshihiro, Naveira Garabato, Alberto, Spingys, Carl, Akhoudas, Camille Hayatte, Sallée, Jean-Baptiste, de Lavergne, Casimir, Abrahamsen, E. Povl, Meijers, Andrew, Meredith, Michael, Zhou, Shenjie, Tamura, Takeshi, Yamazaki, Kaihe, Ohshima, Kay, Falco, Pierpaolo, Budillon, Giorgio, Hattermann, Tore, Janout, Markus, Llanillo, Pedro, Bowen, Melissa, Darelius, Elin, Østerhus, Svein, Nicholls, Keith, Stevens, Craig, Fernandez, Denise, Cimoli, Laura, Jacobs, Stanley, Morrison, Adele, Hogg, Andrew Mcc., Haumann, F. Alexander, Mashayek, Ali, Wang, Zhaomin, Kerr, Rodrigo, Williams, Guy, Lee, Won Sang
• Other Authors: National Oceanography Centre (NOC), Scripps Institution of Oceanography (SIO - UC San Diego), University of California San Diego (UC San Diego), University of California (UC)-University of California (UC), Lamont-Doherty Earth Observatory (LDEO), Columbia University New York, Università degli Studi di Messina = University of Messina (UniMe), Department of Atmospheric and Oceanic Sciences Montréal, McGill University = Université McGill Montréal, Canada, CSIRO Agriculture Flagship, Commonwealth Scientific and Industrial Research Organisation Canberra (CSIRO), Institute for Marine and Antarctic Studies Hobart (IMAS), University of Tasmania Hobart, Australia (UTAS), Institute of Low Temperature Science Sapporo, Hokkaido University Sapporo, Japan, Department of Geological Sciences Stockholm, Stockholm University, Processus et interactions de fine échelle océanique (PROTEO), 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), Nucleus for European Modeling of the Ocean (NEMO R&D )
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: [SDU]Sciences of the Universe [physics]; Antarc*; Antarctic; Ice Sheet; Ice Shelves; Sea ice; Southern Ocean
• Online Access: https://hal.science/hal-04454886; https://hal.science/hal-04454886/document; https://hal.science/hal-04454886/file/fmars-10-1221701.pdf; https://doi.org/10.3389/fmars.2023.1221701

International audience Dense, cold waters formed on Antarctic continental shelves descend along the Antarctic continental margin, where they mix with other Southern Ocean waters to form Antarctic Bottom Water (AABW). AABW then spreads into the deepest parts of all major ocean basins, isolating heat and carbon from the atmosphere for centuries. Despite AABW’s key role in regulating Earth’s climate on long time scales and in recording Southern Ocean conditions, AABW remains poorly observed. This lack of observational data is mostly due to two factors. First, AABW originates on the Antarctic continental shelf and slope where in situ measurements are limited and ocean observations by satellites are hampered by persistent sea ice cover and long periods of darkness in winter. Second, north of the Antarctic continental slope, AABW is found below approximately 2 km depth, where in situ observations are also scarce and satellites cannot provide direct measurements. Here, we review progress made during the past decades in observing AABW. We describe 1) long-term monitoring obtained by moorings, by ship-based surveys, and beneath ice shelves through bore holes; 2) the recent development of autonomous observing tools in coastal Antarctic and deep ocean systems; and 3) alternative approaches including data assimilation models and satellite-derived proxies. The variety of approaches is beginning to transform our understanding of AABW, including its formation processes, temporal variability, and contribution to the lower limb of the global ocean meridional overturning circulation. In particular, these observations highlight the key role played by winds, sea ice, and the Antarctic Ice Sheet in AABW-related processes. We conclude by discussing future avenues for observing and understanding AABW, impressing the need for a sustained and coordinated observing system.