Tide-mediated warming of Arctic halocline by Atlantic heat fluxes over rough topography
Tide-mediated warming of Arctic halocline by Atlantic heat fluxes over rough topography
The largest oceanic heat input to the Arctic Ocean results from inflowing Atlantic water. This inflowing water is warmer than it has been in the past 2,000 years1, 2. Yet the fate of this heat remains uncertain3, partly because the water is relatively saline, and thus dense: it therefore enters the Arctic Ocean at intermediate depths and is separated from surface waters by stratification. Vertical mixing is generally weak within the Arctic Ocean basins, with very modest heat fluxes (0.05–0.3 W m?2) arising largely from double diffusion4, 5, 6, 7, 8. However, geographically limited observations have indicated substantially enhanced turbulent mixing rates over rough topography9, 10, 11, 12, 13, 14. Here we present pan-Arctic microstructure measurements of turbulent kinetic energy dissipation. Our measurements further demonstrate that the enhanced continental slope dissipation rate, and by implication vertical mixing, varies significantly with both topographic steepness and longitude. Furthermore, our observations show that dissipation is insensitive to sea-ice conditions. We identify tides as the main energy source that supports the enhanced dissipation, which generates vertical heat fluxes of more than 50 W m?2. We suggest that the increased transfer of momentum from the atmosphere to the ocean as Arctic sea ice declines is likely to lead to an expansion of mixing hotspots in the future Arctic Ocean.
191-194
Rippeth, Tom P.
249bf4a1-2416-4d49-b7a2-e1e2e1196219
Lincoln, Ben J.
7082f87c-9f2a-415e-9714-df9bb91d871d
Lenn, Yueng-Djern
083a4d58-6bfc-4465-bb58-c2493e873d0a
Green, J.A. Mattias
8996542a-c358-4c2a-bf57-77892943f491
Sundfjord, Arild
ad46cb44-6718-41fd-bbb3-061ec61ee737
Bacon, Sheldon
1e7aa6e3-4fb4-4230-8ba7-90837304a9a7
16 February 2015
Rippeth, Tom P.
249bf4a1-2416-4d49-b7a2-e1e2e1196219
Lincoln, Ben J.
7082f87c-9f2a-415e-9714-df9bb91d871d
Lenn, Yueng-Djern
083a4d58-6bfc-4465-bb58-c2493e873d0a
Green, J.A. Mattias
8996542a-c358-4c2a-bf57-77892943f491
Sundfjord, Arild
ad46cb44-6718-41fd-bbb3-061ec61ee737
Bacon, Sheldon
1e7aa6e3-4fb4-4230-8ba7-90837304a9a7
Rippeth, Tom P., Lincoln, Ben J., Lenn, Yueng-Djern, Green, J.A. Mattias, Sundfjord, Arild and Bacon, Sheldon
(2015)
Tide-mediated warming of Arctic halocline by Atlantic heat fluxes over rough topography.
Nature Geoscience, 8, .
(doi:10.1038/ngeo2350).
Abstract
The largest oceanic heat input to the Arctic Ocean results from inflowing Atlantic water. This inflowing water is warmer than it has been in the past 2,000 years1, 2. Yet the fate of this heat remains uncertain3, partly because the water is relatively saline, and thus dense: it therefore enters the Arctic Ocean at intermediate depths and is separated from surface waters by stratification. Vertical mixing is generally weak within the Arctic Ocean basins, with very modest heat fluxes (0.05–0.3 W m?2) arising largely from double diffusion4, 5, 6, 7, 8. However, geographically limited observations have indicated substantially enhanced turbulent mixing rates over rough topography9, 10, 11, 12, 13, 14. Here we present pan-Arctic microstructure measurements of turbulent kinetic energy dissipation. Our measurements further demonstrate that the enhanced continental slope dissipation rate, and by implication vertical mixing, varies significantly with both topographic steepness and longitude. Furthermore, our observations show that dissipation is insensitive to sea-ice conditions. We identify tides as the main energy source that supports the enhanced dissipation, which generates vertical heat fluxes of more than 50 W m?2. We suggest that the increased transfer of momentum from the atmosphere to the ocean as Arctic sea ice declines is likely to lead to an expansion of mixing hotspots in the future Arctic Ocean.
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Accepted/In Press date: 16 February 2015
Published date: 16 February 2015
Organisations:
Marine Physics and Ocean Climate
Identifiers
Local EPrints ID: 374528
URI: http://eprints.soton.ac.uk/id/eprint/374528
ISSN: 1752-0894
PURE UUID: 36fd1803-9d2f-4088-931d-54fab155b602
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Date deposited: 19 Feb 2015 11:24
Last modified: 14 Mar 2024 19:08
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Author:
Tom P. Rippeth
Author:
Ben J. Lincoln
Author:
Yueng-Djern Lenn
Author:
J.A. Mattias Green
Author:
Arild Sundfjord
Author:
Sheldon Bacon
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