Near-Inertial Energy Propagation inside a Mediterranean Anticyclonic Eddy

Type Article
Date 2020-08
Language English
Author(s) Lelong M.-Pascale1, Cuypers Yannis2, Bouruet-Aubertot Pascale3
Affiliation(s) 1 : NorthWest Research Associates, Redmond, Washington, USA
2 : Sorbonne Universite (UPMC, Univ Paris 06)-CNRS-IRD-MNHN, LOCEAN, Paris, France
3 : Sorbonne Universite (UPMC, Univ Paris 06)-CNRS-IRD-MNHN, LOCEAN, Paris, France
Source Journal Of Physical Oceanography (0022-3670) (American Meteorological Society), 2020-08 , Vol. 50 , N. 8 , P. 2271-2288
DOI 10.1175/JPO-D-19-0211.1
WOS© Times Cited 3
Abstract

Motivated by observations of a strong near-inertial wave signal at the base of the semi-permanent anticyclonic Cyprus eddy during the 2010 BOUM experiment, a numerical study is performed to investigate the role of near-inertial/eddy interactions in energy transfer out of the mixed layer. A hybrid temporal-spatial decomposition is used to split all variables into three independent components: slow (eddy) and fast (inertial oscillations + waves), which proves useful in understanding the flow dynamics. Through a detailed energy budget analysis, we find that the anticyclonic eddy acts as a catalyst in transferring wind-driven inertial energy to propagating waves. While the eddy sets the spatial scales of the waves, it does not participate in any energy exchange. Near-inertial propagation through the eddy core results in the formation of multiple critical levels with the largest accumulation of wave energy at the base of the eddy. A complementary ray-tracing analysis reveals critical level formation when the surface-confined inertial rays originate within the negative vorticity region. In contrast, rays originating outside of this region focus at the base of the eddy and can propagate at depth.

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