Abstract
The exchange of water masses across the Antarctic continental shelf break regulates the export of dense shelf waters to depth as well as the transport of warm, mid-depth waters towards ice shelves and glacial grounding lines1. The penetration of the warmer mid-depth waters past the shelf break has been implicated in the pronounced loss of ice shelf mass over much of west Antarctica2,3,4. In high-resolution, regional circulation models, the Antarctic shelf break hosts an energetic mesoscale eddy field5,6, but observations that capture this mesoscale variability have been limited. Here we show, using hydrographic data collected from ocean gliders, that eddy-induced transport is a primary contributor to mass and property fluxes across the slope. Measurements along ten cross-shelf hydrographic sections show a complex velocity structure and a stratification consistent with an onshore eddy mass flux. We show that the eddy transport and the surface wind-driven transport make comparable contributions to the total overturning circulation. Eddy-induced transport is concentrated in the warm, intermediate layers away from frictional boundaries. We conclude that understanding mesoscale dynamics will be critical for constraining circumpolar heat fluxes and future rates of retreat of Antarctic ice shelves.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 12 print issues and online access
$259.00 per year
only $21.58 per issue
Buy this article
- Purchase on SpringerLink
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Gill, A. E. Circulation and bottom water production in the Weddell Sea. Deep Sea Res. 20, 11–140 (1973).
Shepherd, A., Wingham, D. & Rignot, E. Warm ocean is eroding West Antarctic ice sheet. Geophys. Res. Lett. 31, L23402 (2004).
Pritchard, H. D. et al. Antarctic ice-sheet loss driven by basal melting of ice shelves. Nature 484, 502–505 (2012).
Rignot, E., Jacobs, S., Mouginot, J. & Scheuchl, B. Ice-shelf melting around Antarctica. Science 341, 266–270 (2013).
Thoma, M., Jenkins, A., Holland, D. & Jacobs, S. Modelling circumpolar deep water intrusions on the Amundsen Sea continental shelf, Antarctica. Geophys. Res. Lett. 35, L18602 (2008).
Schodlok, M. P., Menemenlis, D., Rignot, E. & Studinger, M. Sensitivity of the ice-shelf/ocean system to the sub-ice-shelf cavity shape measured by NASA Icebridge in Pine Island Glacier, West Antarctica. Ann. Glaciol. 53, 156–162 (2012).
Marshall, J. & Speer, K. Closure of the meridional overturning circulation through Southern Ocean upwelling. Nature Geosci. 5, 171–180 (2012).
Dinniman, M. S., Klinck, J. M. & Smith, W. O. Jr A model study of circumpolar deep water on the West Antarctic Peninsula and Ross Sea continental shelves. Deep Sea Res. II 58, 1508–1523 (2011).
Nøst, O. A. et al. Eddy overturning of the Antarctic slope front controls glacial melting in the eastern Weddell Sea. J. Geophys. Res. 116, C11014 (2011).
Stewart, A. L. & Thompson, A. F. Connecting Antarctic cross-slope exchange with Southern Ocean overturning. J. Phys. Oceanogr. 43, 1453–1471 (2013).
Gordon, A. L., Huber, B., McKee, D. & Visbeck, M. A seasonal cycle in the export of bottom water from the Weddell Sea. Nature Geosci. 3, 551–556 (2010).
Spall, M. A. Dense water formation around islands. J. Geophys. Res. 118, 2507–2519 (2013).
Orsi, A. H., Johnson, G. C. & Bullister, J. L. Circulation, mixing, and production of Antarctic Bottom Water. Prog. Oceanogr. 43, 55–109 (1999).
Korb, R. E. & Whitehouse, M. Contrasting primary production regimes around South Georgia, Southern Ocean: Large blooms versus high nutrient, low chlorophyll waters. Deep Sea Res. I 51, 721–738 (2004).
Tagliabue, A., Bopp, L. & Aumont, O. Evaluating the importance of atmospheric and sedimentary iron sources to Southern Ocean biogeochemistry. Geophys. Res. Lett. 36, L13601 (2009).
Baines, P. G. & Condie, S. Ocean, Ice and Atmosphere: Interactions at the Antarctic Continental Margins, Antarctic Research Series Vol. 75, 29–49 (1998).
Speer, K., Rintoul, S. R. & Sloyan, B. The diabatic Deacon cell. J. Phys. Oceanogr. 30, 3212–3222 (2000).
Jullion, L. et al. Decadal freshening of the Antarctic bottom water exported from the Weddell Sea. J. Clim. 26, 8111–8125 (2013).
Jacobs, S. S. On the nature and significance of the Antarctic slope front. Mar. Chem. 35, 9–24 (1991).
Plumb, R. A. Three-dimensional propagation of transient quasi-geostrophic eddies and its relationship with the eddy forcing of the time-mean flow. J. Atmos. Sci. 43, 1657–1678 (1986).
Spall, M. A., Pickart, R. S., Fratantoni, P. S. & Plueddemann, A. J. Western Arctic shelfbreak eddies: Formation and transport. J. Phys. Oceanogr. 38, 1644–1668 (2008).
Visbeck, M., Marshall, M., Haine, T. & Spall, M. Specification of eddy transfer coefficients in coarse-resolution ocean circulation models. J. Phys. Oceanogr. 27, 381–402 (1997).
Wåhlin, A. K., Yuan, X., Björk, G. & Nohr, C. Inflow of warm Circumpolar Deep Water in the central Amundsen shelf. J. Phys. Oceanogr. 40, 1427–1434 (2010).
St Laurent, P., Klinck, J. M. & Dinniman, M. S. On the role of coastal troughs in the circulation of warm circumpolar deep water on Antarctic shelves. J. Phys. Oceanogr. 43, 51–64 (2013).
Gent, P. R. & McWilliams, J. C. Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr. 20, 150–155 (1990).
Isachsen, P. E. Baroclinic instability and eddy tracer transport across sloping bottom topography: How well does a modified Eady model do in primitive equation simulations? Ocean Model. 39, 183–199 (2011).
Ou, H-W. Watermass properties of the Antarctic slope front: A simple model. J. Phys. Oceanogr. 37, 50–59 (2007).
Purkey, S. G. & Johnson, G. C. Global contraction of Antarctic bottom water between the 1980s and 2000s. J. Clim. 25, 5830–5844 (2012).
Joughin, I., Smith, B. E. & Medley, B. Marine ice sheet collapse potentially under way of the Thwaites glacier basin, West Antarctica. Science 344, 735–738 (2014).
Thompson, A. F. & Youngs, M. K. Surface exchange between the Weddell and Scotia Seas. Geophys. Res. Lett. 40, 5920–5925 (2013).
Acknowledgements
The authors thank the officers and crew of the RRS James Clark Ross for help in deploying and recovering the gliders. A.F.T. was financially supported by NSF award OPP-1246460. S.S. and K.J.H. were financially supported by the NERC Antarctic Funding Initiative research grant GENTOO NE/H01439X/1. A.L.S. was supported by the President’s and Director’s Fund program at Caltech.
Author information
Authors and Affiliations
Contributions
K.J.H. and A.F.T. conceived and designed the field program; A.F.T., K.J.H. and S.S. collected the data; S.S. processed the data; A.F.T. and S.S. analysed the data; A.F.T., K.J.H., S.S. and A.L.S. co-wrote the paper.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing financial interests.
Supplementary information
Supplementary Information
Supplementary Information (PDF 854 kb)
Rights and permissions
About this article
Cite this article
Thompson, A., Heywood, K., Schmidtko, S. et al. Eddy transport as a key component of the Antarctic overturning circulation. Nature Geosci 7, 879–884 (2014). https://doi.org/10.1038/ngeo2289
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/ngeo2289
This article is cited by
-
Persistent warm-eddy transport to Antarctic ice shelves driven by enhanced summer westerlies
Nature Communications (2024)
-
Submesoscale inverse energy cascade enhances Southern Ocean eddy heat transport
Nature Communications (2023)
-
Statistical characteristics and thermohaline properties of mesoscale eddies in the Bay of Bengal
Acta Oceanologica Sinica (2021)
-
Monitoring ocean biogeochemistry with autonomous platforms
Nature Reviews Earth & Environment (2020)
-
Identification and census statistics of multicore eddies based on sea surface height data in global oceans
Acta Oceanologica Sinica (2020)