Observational evidence of diapycnal upwelling within a sloping submarine canyon
Type | Article | ||||||||
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Acceptance Date | 2023-10-20 IN PRESS | ||||||||
Language | English | ||||||||
Author(s) | Wynne-Cattanach Bethan1, Alford Matthew1, Couto Nicole1, Drake Henri2, Ferrari Raffaele3, Le Boyer Arnaud1, Mercier Herle4, Messias Marie-Jose5, Naveira Garabato Alberto6, Polzin Kurt7, Ruan Xiaozhou8, Spingys Carl9, Van haren Hans10, Voet Gunnar1 | ||||||||
Affiliation(s) | 1 : Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92037, USA 2 : Princeton University / Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08540, USA 3 : Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA 4 : Laboratoire d’Océanographie Physique et Spatiale, CNRS, Ifremer Centre de Bretagne, Plouzané, France 5 : Deparment of Geography, University of Exeter, Exeter, EX4 4QE, UK 6 : Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton, SO14 3ZH, UK 7 : Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA 8 : Department of Earth and Environment, Boston University, Boston, MA 02215, USA 9 : National Oceanography Centre, Southampton, SO14 3ZH, UK 10 : Royal Netherlands Institute for Sea Research (NIOZ), P.O. Box 59, 1790 AB Den Burg, 30 the Netherlands. |
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Source | Under Review at Nature Portfolio (Research Square Platform LLC) In Press | ||||||||
DOI | 10.21203/rs.3.rs-3459062/v1 | ||||||||
Note | This is a preprint ; it has not been peer reviewed by a journal | ||||||||
Abstract | Small-scale turbulent mixing drives the upwelling of deep water masses in the abyssal ocean as part of the global overturning circulation (Wunsch & Ferrari 2004). However, the processes leading to mixing and the pathways through which this upwelling occurs remain insufficiently understood. Recent observational and theoretical work suggests that deep water upwelling may be focused in bottom boundary layers on the ocean’s sloping seafloor; however, direct evidence of this is lacking (Ledwell et al. 2000, St. Laurent et al. 2001, Ferrari et al. 2016, de Lavergne et al. 2016). Here, we present observations from a near-bottom dye release within a canyon on the North Atlantic continental slope showing upwelling across density surfaces at a rate of 250 +/- 75 m/day over three days, ∼10,000 times higher than the global average value required to account for ∼30 Sv of upwelling globally (Munk 1966). The vigourous upwelling is coupled with adiabatic exchange of near-boundary and interior fluid. These results provide direct evidence of strong, bottom-focused diapycnal upwelling in the deep ocean, supporting previous suggestions that mixing at topographic features, such as canyons, leads to upwelling. |
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