Accueil > Actualités > Séminaires > Séminaire de Lia Siegelman


Titre : Energetic submesoscale dynamics in the ocean interior
Nom du conférencier : Lia Siegelman
Son affiliation : Scripps Institution of Oceanography, UCSD
Laboratoire organisateur : LMD
Date et heure : 07-12-2020 17h00
Lieu : En ligne
Résumé :

This talk investigates submesoscale fronts (< 50 km size) and their link to oceanic vertical heat transport. To date, submesoscale motions are thought to be mainly trapped within the ocean surface mixed layer, and to be weak in the ocean interior. This is because, in the classical paradigm, motions below the mixed layer are broadly assumed to be in quasi-geostrophic balance, preventing the formation of strong buoyancy gradients at depth. This talk introduces a paradigm shift; based on a combination of high-resolution in situ CTD data collected by instrumented elephant seals, satellite observations of sea surface height, and high-resolution model outputs in the Antarctic Circumpolar Current, we show that energetic submesoscale motions (i) are generated by the background mesoscale eddy field via frontogenesis processes, and (ii) are not solely confined to the ocean surface mixed layer but, rather, can extend in the ocean interior down to depths of 1 000 m. Deep-reaching submesoscale fronts are shown to drive an anomalous upward heat transport from the ocean interior back to the surface that is of comparable magnitude to air-sea fluxes. This effect can potentially alter 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. As such, submesoscale fronts provide an important, yet unexplored, pathway for the transport of heat, chemical and biological tracers, between the ocean interior and the surface, with potential major implications for the biogeochemical and climate systems.

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