Observations of diapycnal upwelling within a sloping submarine canyon.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38926613.
- Also identified by DOI 10.1038/s41586-024-07411-2 and PMC identifier 11208136.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Small-scale turbulent mixing drives the upwelling of deep water masses in the abyssal ocean as part of the global overturning circulation<sup>1</sup>. However, the processes leading to mixing and the pathways through which this upwelling occurs remain insufficiently understood. Recent observational and theoretical work<sup>2-5</sup> has suggested that deep-water upwelling may occur along the ocean's sloping seafloor; however, evidence has, so far, been indirect. Here we show vigorous near-bottom upwelling across isopycnals at a rate of the order of 100 metres per day, coupled with adiabatic exchange of near-boundary and interior fluid. These observations were made using a dye released close to the seafloor within a sloping submarine canyon, and they provide direct evidence of strong, bottom-focused diapycnal upwelling in the deep ocean. This supports previous suggestions that mixing at topographic features, such as canyons, leads to globally significant upwelling<sup>3,6-8</sup>. The upwelling rates observed were approximately 10,000 times higher than the global average value required for approximately 30 × 10<sup>6</sup> m<sup>3</sup> s<sup>-1</sup> of net upwelling globally<sup>9</sup>.