Impact of ocean-atmosphere current feedback on the ocean mesoscale activity: regional variations, and sensitivity to model resolution

Type Article
Date 2020-04
Language English
Author(s) Jullien SwenORCID1, Masson Sébastien2, Oerder Véra3, Samson Guillaume4, Colas François2, Renault Lionel5, 6
Affiliation(s) 1 : Ifremer, Univ. Brest, CNRS, IRD, Laboratoire d’Oceanographie Physique et Spatiale (LOPS), IUEM, Brest, France
2 : LOCEAN-IPSL, Sorbonne Universite-CNRS-IRD-MNHN, 4 place Jussieu, F-75005 Paris, France
3 : Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso, Chile
4 : Mercator Ocean, Ramonville-Saint-Agne, France
5 : University of Toulouse, IRD, CNRS, CNES, UPS, LEGOS, Toulouse, France
6 : Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA, USA
Source Journal Of Climate (0894-8755) (American Meteorological Society), 2020-04 , Vol. 33 , N. 7 , P. 2585-2602
DOI 10.1175/JCLI-D-19-0484.1
WOS© Times Cited 17
Note This article is included in the Climate Implications of Frontal Scale Air–Sea Interaction Special Collection.
Keyword(s) Currents, Feedback, Mesoscale processes, Air-sea interaction, Coupled models, Mesoscale models

Ocean mesoscale eddies are characterized by rotating-like and meandering currents that imprint the low-level atmosphere. Such a current feedback (CFB) has been shown to induce a sink of energy from the ocean to the atmosphere, and consequently to damp the eddy kinetic energy (EKE), with an apparent regional disparity. In a context of increasing model resolution, the importance of this feedback, and its dependence on oceanic and atmospheric models resolution arise. Using a hierarchy of quasi-global coupled models with spatial resolutions varying from ¼° to 1/12°, the present study shows that the CFB induces a negative wind work at scales ranging from 100 to 1000 km, and a subsequent damping of the mesoscale activity by ∼30% on average, independently of the model resolution. Regional variations of this damping range from ∼20% in very rich-eddying regions to ∼40% in poor-eddying regions. This regional modulation is associated to a different balance between the sink of energy by eddy wind work, and the source of EKE by ocean intrinsic instabilities. The efficiency of the CFB is also shown to be a function of the surface wind magnitude: the larger the wind, the larger the sink of energy. The CFB impact is thus related to both wind and EKE. Its correct representation requires both an ocean model that resolves the mesoscale field adequately, and an atmospheric model resolution that matches the ocean effective resolution and allows a realistic representation of wind patterns. These results are crucial for including adequately mesoscale ocean-atmosphere interactions in coupled general circulation models, and have strong implications in climate research.

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Jullien Swen, Masson Sébastien, Oerder Véra, Samson Guillaume, Colas François, Renault Lionel (2020). Impact of ocean-atmosphere current feedback on the ocean mesoscale activity: regional variations, and sensitivity to model resolution. Journal Of Climate, 33(7), 2585-2602. Publisher's official version : , Open Access version :