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Southern Ocean frontal structure and sea-ice formation rates revealed by elephant seals

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Charrassin, JB and Hindell, MA and Rintoul, SR and Roquet, F and Sokolov, S and Biuw, M and Costa, D and Boehme, L and Lovell, P and Coleman, R and Timmermann, R and Meijers, AJ and Meredith, M and Park, YH and Bailleul, F and Goebel, M and Tremblay, Y and Bost, CA and McMahon, CR and Field, IC and Fedak, MA and Guinet, C (2008) Southern Ocean frontal structure and sea-ice formation rates revealed by elephant seals. Proceedings of the National Academy of Sciences of the United States PNAS, 105 (33). pp. 11634-11639. ISSN 0027-8424

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Abstract

Polar regions are particularly sensitive to climate change, with the potential for significant feedbacks between ocean circulation, sea ice, and the ocean carbon cycle. However, the difficulty in obtaining in situ data means that our ability to detect and interpret change is very limited, especially in the Southern Ocean, where the ocean beneath the sea ice remains almost entirely unobserved and the rate of sea-ice formation is poorly known. Here, we show that southern elephant seals (Mirounga leonina) equipped with oceanographic sensors can measure ocean structure and water mass changes in regions and seasons rarely observed with traditional oceanographic platforms. In particular, seals provided a 30-fold increase in hydrographic profiles from the sea-ice zone, allowing the major fronts to be mapped south of 60°S and sea-ice formation rates to be inferred from changes in upper ocean salinity. Sea-ice production rates peaked in early winter (April–May) during the rapid northward expansion of the pack ice and declined by a factor of 2 to 3 between May and August, in agreement with a threedimensional coupled ocean–sea-ice model. By measuring the highlatitude ocean during winter, elephant seals fill a ‘‘blind spot’’ in our sampling coverage, enabling the establishment of a truly global ocean-observing system.

Item Type: Article
Keywords: Antarctic Circumpolar Current instrumentation marine predators
Journal or Publication Title: Proceedings of the National Academy of Sciences of the United States PNAS
Page Range: pp. 11634-11639
ISSN: 0027-8424
Identification Number - DOI: 10.1073/pnas.0800790105
Date Deposited: 04 Mar 2009 03:17
Last Modified: 18 Nov 2014 03:56
URI: http://eprints.utas.edu.au/id/eprint/8400
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