Ventilation of the abyss in the Atlantic sector of the Southern Ocean

Akhoudas, Camille Hayatte; Sall�e, Jean Baptiste; Haumann, F. Alexander; Meredith, Michael P.; Garabato, Alberto Naveira; Reverdin, Gilles; Jullion, Lo�c; Aloisi, Giovanni; Benetti, Marion; Leng, Melanie J.; Arrowsmith, Carol

Abstract

The Atlantic sector of the Southern Ocean is the world’s main production site of Antarctic Bottom Water, a water-mass that is ventilated at the ocean surface before sinking and entraining older water-masses—ultimately replenishing the abyssal global ocean. In recent decades, numerous attempts at estimating the rates of ventilation and overturning of Antarctic Bottom Water in this region have led to a strikingly broad range of results, with water transport-based calculations (8.4–9.7 Sv) yielding larger rates than tracer-based estimates (3.7–4.9 Sv). Here, we reconcile these conflicting views by integrating transport- and tracer-based estimates within a common analytical framework, in which bottom water formation processes are explicitly quantified. We show that the layer of Antarctic Bottom Water denser than 28.36 kg m−3 γn is exported northward at a rate of 8.4 ± 0.7 Sv, composed of 4.5 ± 0.3 Sv of well-ventilated Dense Shelf Water, and 3.9 ± 0.5 Sv of old Circumpolar Deep Water entrained into cascading plumes. The majority, but not all, of the Dense Shelf Water (3.4 ± 0.6 Sv) is generated on the continental shelves of the Weddell Sea. Only 55% of AABW exported from the region is well ventilated and thus draws down heat and carbon into the deep ocean. Our findings unify traditionally contrasting views of Antarctic Bottom Water production in the Atlantic sector, and define a baseline, process-discerning target for its realistic representation in climate models.

Citation

Akhoudas, C. H., Sallée, J. B., Haumann, F. A., Meredith, M. P., Garabato, A. N., Reverdin, G., …Arrowsmith, C. (2021). Ventilation of the abyss in the Atlantic sector of the Southern Ocean. Scientific Reports, 11(1), Article 6760. https://doi.org/10.1038/s41598-021-86043-2

• Journal Article Type: Article
• Acceptance Date: Mar 9, 2021
• Online Publication Date: Mar 24, 2021
• Publication Date: Dec 1, 2021
• Deposit Date: Mar 25, 2021
• Publicly Available Date: Mar 25, 2021
• Journal: Scientific Reports
• Electronic ISSN: 2045-2322
• Publisher: Nature Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 11
• Issue: 1
• Article Number: 6760
• DOI: https://doi.org/10.1038/s41598-021-86043-2
• Keywords: Multidisciplinary
• Public URL: https://nottingham-repository.worktribe.com/output/5415200
• Publisher URL: https://www.nature.com/articles/s41598-021-86043-2
• Additional Information: Received: 26 May 2020; Accepted: 9 March 2021; First Online: 24 March 2021; : The authors declare no competing interests.