Connecting Mixing to Upwelling along the Ocean's Sloping Boundary
Deep-ocean upwelling, driven by small-scale turbulence, plays a key role in climate by regulating the ocean’s capacity to sequester heat and carbon. Recent theoretical studies have hypothesized that such upwelling may primarily occur within a bottom boundary layer (BBL) along the sloping seafloor. A recent dye experiment in a continental-slope canyon as part of the BLT-Recipes program revealed very rapid BBL-focussed upwelling, endorsing this notion. Here, we elucidate the mixing processes governing the upwelling. We show that along-canyon upwelling stems from episodic turbulent mixing cells up to 250 m high, generated by tides sweeping up- and down-canyon. The tidal currents support a vertical shear that advects dense waters over slower-flowing lighter waters, reducing BBL stratification. This triggers instabilities that mix the dense waters with neighboring lighter waters, resulting in a net along-boundary upwelling flow. Our findings substantiate the view that deep-ocean upwelling can predominantly occur along the ocean’s sloping boundaries.
Authors
- Alberto C. Naveira Garabato (ORCID: https://orcid.org/0000-0001-6071-605X)
- Yuchen Ma (ORCID: https://orcid.org/0000-0002-9990-5023)
- Herlé Mercier (ORCID: https://orcid.org/0000-0002-1940-617X)
- Bethan Wynne‐Cattanach (ORCID: https://orcid.org/0000-0003-4960-2419)
- Marie‐José Messias (ORCID: https://orcid.org/0000-0002-3852-2854)
- Matthew H. Alford (ORCID: https://orcid.org/0000-0002-6318-0737)
- Gunnar Voet (ORCID: https://orcid.org/0000-0003-1975-186X)
- Alexander Forryan
- Raffaele Ferrari (ORCID: https://orcid.org/0000-0003-1895-4294)
- Nicole Couto (ORCID: https://orcid.org/0000-0002-5330-9592)
- Carl Spingys (ORCID: https://orcid.org/0000-0001-6220-3047)
- Bieito Fernández Castro (ORCID: https://orcid.org/0000-0001-7797-854X)
- Kurt L. Polzin (ORCID: https://orcid.org/0000-0002-9991-1941)
- Zhiyuan Gao (ORCID: https://orcid.org/0000-0003-2726-7664)
- Xiaozhou Ruan (ORCID: https://orcid.org/0000-0003-1240-1584)
- Henri F. Drake (ORCID: https://orcid.org/0000-0003-0135-0814)
Institutions
- Centre National de la Recherche Scientifique (FR)
- Scripps Institution of Oceanography (US)
- National Oceanography Centre (GB)
- University of California, Irvine (US)
- University of Exeter (GB)
- University of Cambridge (GB)
- University of California San Diego (US)
- National Council for Scientific Research (LB)
- Scripps (United States) (US)
- University of Southampton (GB)
- Ocean University of China (CN)
- Massachusetts Institute of Technology (US)
- Woods Hole Oceanographic Institution (US)
Publication Details
- Published
- 2025-09-12
- DOI
- https://doi.org/10.22541/essoar.175767179.90159335/v1
- Primary Topic
- Oceanographic and Atmospheric Processes
- Type
- article
- Field-Weighted Citation Impact
- 0.00