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

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Charrassin, JB, Hindell, MA, Rintoul, SR, Roquet, F, Sokolov, S, Biuw, M, Costa, D, Boehme, L, Lovell, P, Coleman, R, Timmermann, R, Meijers, AJ, Meredith, M, Park, YH, Bailleul, F, Goebel, M, Tremblay, Y, Bost, CA, McMahon, CR, Field, IC, Fedak, MA, Guinet, C
• Format: Article in Journal/Newspaper
• Language: English
• Published: National Academy of Sciences 2008
• Subjects: Earth Sciences; Oceanography; Physical Oceanography; Southern Ocean; Elephant Seals; Mirounga leonina; Sea ice
• Online Access: http://www.pnas.org; https://doi.org/10.1073/pnas.0800790105; http://www.ncbi.nlm.nih.gov/pubmed/18695241; http://ecite.utas.edu.au/54600

Polar regions are particularly sensitive to climate change, with thepotential for significant feedbacks between ocean circulation, seaice, and the ocean carbon cycle. However, the difficulty in obtainingin situ data means that our ability to detect and interpretchange is very limited, especially in the Southern Ocean, where theocean beneath the sea ice remains almost entirely unobserved andthe rate of sea-ice formation is poorly known. Here, we show thatsouthern elephant seals (Mirounga leonina) equipped with oceanographicsensors can measure ocean structure and water masschanges in regions and seasons rarely observed with traditionaloceanographic platforms. In particular, seals provided a 30-foldincrease in hydrographic profiles from the sea-ice zone, allowingthe major fronts to be mapped south of 60S and sea-ice formationrates to be inferred from changes in upper ocean salinity. Sea-iceproduction rates peaked in early winter (AprilMay) during therapid northward expansion of the pack ice and declined by a factorof 2 to 3 between May and August, in agreement with a threedimensionalcoupled oceansea-ice model. By measuring the highlatitudeocean during winter, elephant seals fill a blind spot inour sampling coverage, enabling the establishment of a trulyglobal ocean-observing system.