Enhanced upward heat transport at deep submesoscale ocean fronts

• Published in: Nature Geoscience
• Main Authors: Siegelman, Lia, Klein, Patrice, Rivière, Pascal, Thompson, Andrew F., Torres, Hector S., Flexas, Mar, Menemenlis, Dimitris
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Nature Publishing Group 2020
• Subjects: Physical oceanography; Antarctic; The Antarctic; Antarc*; Elephant Seal; Elephant Seals
• Online Access: https://doi.org/10.1038/s41561-019-0489-1

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. © 2019 Springer Nature Limited. Received 18 June 2019; Accepted 16 October 2019; Published 02 December 2019. We thank K. Richards for his insightful comments, F. d'Ovidio for providing the code to compute FSLE. The elephant seal work was supported as part of the SNO-MEMO and by the CNES-TOSCA project Elephant seals as Oceanographic Samplers of submesoscale features led by C. Guinet with support of the French Polar Institute (programmes 109 and 1201). This research was carried out, in part, at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). High-end computing resources for the numerical simulation were provided by the NASA Advanced Supercomputing Division at the Ames Research ...