Freshwater fluxes in the Weddell Gyre: results from δ18O

Brown, Peter J.; Meredith, Michael P. ORCID: https://orcid.org/0000-0002-7342-7756; Jullion, Loic; Naveira Garabato, Alberto; Torres-Valdes, Sinhue; Holland, Paul ORCID: https://orcid.org/0000-0001-8370-289X; Leng, Melanie J. ORCID: https://orcid.org/0000-0003-1115-5166; Venables, Hugh ORCID: https://orcid.org/0000-0002-6445-8462. 2014 Freshwater fluxes in the Weddell Gyre: results from δ18O. Philosophical Transactions of the Royal Society of London, A, 372 (2019), 20130298. https://doi.org/10.1098/rsta.2013.0298

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Text (An edited version of this paper was published in Philosophical Transactions of the Royal Society A. Copyright held by the Royal Society) o18manuscript_PTRSv4_finalfigs.docx - Accepted Version Download (1MB)

Abstract/Summary

Full-depth measurements of δ18O from 2008 to 2010 enclosing the Weddell Gyre in the Southern Ocean are used to investigate the regional freshwater budget. Using complementary salinity, nutrients and oxygen data, a four-component mass balance was applied to quantify the relative contributions of meteoric water (precipitation/glacial input), sea-ice melt and saline (oceanic) sources. Combination of freshwater fractions with velocity fields derived from a box inverse analysis enabled the estimation of gyre-scale budgets of both freshwater types, with deep water exports found to dominate the budget. Surface net sea-ice melt and meteoric contributions reach 1.8% and 3.2%, respectively, influenced by the summer sampling period, and −1.7% and +1.7% at depth, indicative of a dominance of sea-ice production over melt and a sizable contribution of shelf waters to deep water mass formation. A net meteoric water export of approximately 37 mSv is determined, commensurate with local estimates of ice sheet outflow and precipitation, and the Weddell Gyre is estimated to be a region of net sea-ice production. These results constitute the first synoptic benchmarking of sea-ice and meteoric exports from the Weddell Gyre, against which future change associated with an accelerating hydrological cycle, ocean climate change and evolving Antarctic glacial mass balance can be determined.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1098/rsta.2013.0298
Programmes:	BAS Programmes > Polar Science for Planet Earth (2009 - ) > Polar Oceans NOC Programmes > Ocean Biogeochemistry and Ecosystems
ISSN:	1364-503X
Additional Keywords:	Antarctic Bottom Water, freshwater cycle, oxygen isotope, dense water export
Date made live:	09 Jun 2014 10:12 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/503239

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