Highly variable deep-sea currents over tidal and seasonal timescales

Bailey, Lewis P.; Clare, Michael A. ORCID: https://orcid.org/0000-0003-1448-3878; Hunt, James E.; Kane, Ian A.; Miramontes, Elda; Fonnesu, Marco; Argiolas, Ricardo; Malgesini, Giuseppe; Wallerand, Regis. 2024 Highly variable deep-sea currents over tidal and seasonal timescales. Nature Geoscience, 17 (8). 787-794. https://doi.org/10.1038/s41561-024-01494-2

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Abstract/Summary

Deep-sea transport of sediment and associated matter, such as organic carbon, nutrients and pollutants, is controlled by near-bed currents. On the continental slope, these currents include episodic down-slope gravity-driven turbidity currents and more sustained thermohaline-driven along-slope contour currents. Recent advancements in deep-sea monitoring have catalysed a step change in our understanding of turbidity currents and contour currents individually. However, these processes rarely operate in isolation and the near-bed current regime is still to be quantified in a mixed system. Such measurements are crucial for understanding deep-sea particulate transport, calibrating numerical models and reconstructing palaeoflow. Here we use 4 years of observations from 34 instrument moorings in a mixed system offshore of Mozambique to show that near-bed currents are highly dynamic. We observe spatial variability in velocity over tidal and seasonal timescales, including reversals in current direction, and a strong steering and funnelling influence by local seabed morphology. The observed near-bed currents are capable of mobilizing and distributing sediments across the seabed, therefore complicating deep-sea particulate transport and reconstruction of palaeoceanographic conditions.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1038/s41561-024-01494-2
ISSN:	1752-0894
Date made live:	14 Aug 2024 12:34 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/537857

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