Spiraling pathways of global deep waters to the surface of the Southern Ocean

• Published in: Nature Communications
• Main Authors: Tamsitt, Veronica, Drake, Henri F., Morrison, Adele, Talley, Lynne D., Dufour, Carolina O, Gray, Alison R., Griffies, S.M., Mazloff, Matthew, Sarmiento, Jorge L, Wang, Jinbo, Weijer, Wilbert
• Format: Article in Journal/Newspaper
• Language: English
• Published: Macmillan Publishers Ltd
• Subjects: Antarctic; Southern Ocean; The Antarctic; Antarc*; Ice Shelves
• Online Access: http://hdl.handle.net/1885/248250; https://doi.org/10.1038/s41467-017-00197-0; https://openresearch-repository.anu.edu.au/bitstream/1885/248250/3/01_Tamsitt_Spiraling_pathways_of_global_2017.pdf.jpg

Upwelling of global deep waters to the sea surface in the Southern Ocean closes the global overturning circulation and is fundamentally important for oceanic uptake of carbon and heat, nutrient resupply for sustaining oceanic biological production, and the melt rate of ice shelves. However, the exact pathways and role of topography in Southern Ocean upwelling remain largely unknown. Here we show detailed upwelling pathways in three dimensions, using hydrographic observations and particle tracking in high-resolution models. The analysis reveals that the northern-sourced deep waters enter the Antarctic Circumpolar Current via southward flow along the boundaries of the three ocean basins, before spiraling southeastward and upward through the Antarctic Circumpolar Current. Upwelling is greatly enhanced at five major topographic features, associated with vigorous mesoscale eddy activity. Deep water reaches the upper ocean predominantly south of the Antarctic Circumpolar Current, with a spatially nonuniform distribution. The timescale for half of the deep water to upwell from 30° S to the mixed layer is ~60–90 years. V.T., L.D.T., and M.R.M. were supported by NSF OCE-1357072. A.K.M., H.F.D., and W.W. were supported by the RGCM program of the US Department of Energy under Contract DE-SC0012457. J.L.S. acknowledges NSF’s Southern Ocean Carbon and Climate Observations and Modeling project under NSF PLR-1425989, which partially supported L.D.T. and M.R.M. as well. C.O.D was supported by the National Aeronautics and Space Administration (NASA) under Award NNX14AL40G and by the Princeton Environmental Institute Grand Challenge initiative. A.R.G. was supported by a Climate and Global Change Postdoctoral Fellowship from the National Oceanic and Atmospheric Administration (NOAA). S.M.G. acknowledges the ongoing support of NOAA/GFDL for high-end ocean and climate-modeling activities. J.W. acknowledges support from NSF OCE-1234473 and declare that this work was done as a private venture and not in the author’s capacity as an ...