Contrasted turbulence intensities in the Indonesian Throughflow: a challenge for parameterizing energy dissipation rate

Type Article
Date 2018-07
Language English
Author(s) Bouruet-Aubertot Pascale1, Cuypers Yannis1, Ferron Bruno4, Dausse Denis1, Menage Olivier2, Atmadipoera Agus3, Jaya Indra3
Affiliation(s) 1 : UPMC Univ Paris 06, Sorbonne Univ, LOCEAN, Paris 06, France.
2 : LOPS Ifremer, Plouzane, France.
3 : IPB, Bogor, Indonesia.
Source Ocean Dynamics (1616-7341) (Springer Heidelberg), 2018-07 , Vol. 68 , N. 7 , P. 779-800
DOI 10.1007/s10236-018-1159-3
WOS© Times Cited 8
Keyword(s) Turbulence, Internal tides, Vertical mixing, Parameterization, Indonesian seas, Microstructure measurements
Abstract

Microstructure measurements were performed along two sections through the Halmahera Sea and the Ombai Strait and at a station in the deep Banda Sea. Contrasting dissipation rates (𝜖) and vertical eddy diffusivities (K z ) were obtained with depth-averaged ranges of ∼[9×10−10−10−5] W kg− 1 and of ∼[1×10−5−2×10−3] m2 s− 1, respectively. Similarly, turbulence intensity, I=ϵ/(νN2) with ν the kinematic viscosity and N the buoyancy frequency, was found to vary seven orders of magnitude with values up to 107. These large ranges of variations were correlated with the internal tide energy level, which highlights the contrast between regions close and far from internal tide generations. Finescale parameterizations of 𝜖 induced by the breaking of weakly nonlinear internal waves were only relevant in regions located far from any generation area (“far field”), at the deep Banda Sea station. Closer to generation areas, at the “intermediate field” station of the Halmahera Sea, a modified formulation of MacKinnon and Gregg (2005) was validated for moderately turbulent regimes with 100 < I < 1000. Near generation areas marked by strong turbulent regimes such as “near field” stations within strait and passages, 𝜖 is most adequately inferred from horizontal velocities provided that part of the inertial subrange is resolved, according to Kolmogorov scaling.

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Bouruet-Aubertot Pascale, Cuypers Yannis, Ferron Bruno, Dausse Denis, Menage Olivier, Atmadipoera Agus, Jaya Indra (2018). Contrasted turbulence intensities in the Indonesian Throughflow: a challenge for parameterizing energy dissipation rate. Ocean Dynamics, 68(7), 779-800. Publisher's official version : https://doi.org/10.1007/s10236-018-1159-3 , Open Access version : https://archimer.ifremer.fr/doc/00441/55240/