Enhanced upward heat transport at deep submesoscale ocean fronts

Type Article
Date 2020-01
Language English
Author(s) Siegelman Lia1, 2, 3, Klein Patrice1, 2, 4, Rivière Pascal3, Thompson Andrew F.1, Torres Hector S.2, Flexas Mar1, Menemenlis Dimitris2
Affiliation(s) 1 : Environmental Science and Engineering, California Institute of Technology, Pasadena, CA, USA
2 : Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
3 : Université de Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané, France
4 : Université de Brest, CNRS, IRD, Ifremer, LOPS, Plouzané, France
Source Nature Geoscience (1752-0894) (Springer Science and Business Media LLC), 2020-01 , Vol. 13 , N. 1 , P. 50-55
DOI 10.1038/s41561-019-0489-1
WOS© Times Cited 23
Note Extended Data Fig. 1 Weakly turbulent and southern eddy edge areas. Extended Data Fig. 2 Lateral gradient of buoyancy and Richardson number in the strongly turbulent area. Extended Data Fig. 3 Map of finite size Lyapunov exponents. Extended Data Fig. 4 Finite size Lyapunov exponents and horizontal gradient of buoyancy, vertical velocities and vertical heat transport at 300 m. Extended Data Fig. 5 Daily averaged vertical velocities and vertical heat transport from the high-resolution numerical simulation. Extended Data Fig. 6 Averaged vertical heat transport from the high-resolution numerical simulation. Extended Data Fig. 7 Domain averaged vertical heat transport from the high-resolution numerical simulation. Extended Data Fig. 8 Distance between two dives and angle between the seal’s trajectory and the fronts.
Abstract

The ocean is the largest solar energy collector on Earth. The amount of heat it can store is modulated by its complex circulation, which spans a broad range of spatial scales, from metres to thousands of kilometres. In the classical paradigm, fine oceanic scales, less than 20 km in size, are thought to drive a significant downward heat transport from the surface to the ocean interior, which increases oceanic heat uptake. Here we use a combination of satellite and in situ observations in the Antarctic Circumpolar Current to diagnose oceanic vertical heat transport. The results explicitly demonstrate how deep-reaching submesoscale fronts, with a size smaller than 20 km, are generated by mesoscale eddies of size 50–300 km. In contrast to the classical paradigm, these submesoscale fronts are shown to drive an anomalous upward heat transport from the ocean interior back to the surface that is larger than other contributions to vertical heat transport and of comparable magnitude to air–sea fluxes. This effect can remarkably alter the oceanic heat uptake and will be strongest in eddy-rich regions, such as the Antarctic Circumpolar Current, the Kuroshio Extension and the Gulf Stream, all of which are key players in the climate system.

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