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Deep cycle turbulence in Atlantic and Pacific cold tongues
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  • Jim Moum,
  • Kenneth G. Hughes,
  • Emily L Shroyer,
  • William Smyth,
  • Deepak Cherian,
  • Sally Jane Warner,
  • Bernard Bourlès,
  • Peter Brandt,
  • Marcus Dengler
Jim Moum
Oregon State University

Corresponding Author:[email protected]

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Kenneth G. Hughes
Oregon State University
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Emily L Shroyer
Office of Naval Research
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William Smyth
OSU
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Deepak Cherian
NCAR
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Sally Jane Warner
Brandeis University
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Bernard Bourlès
IRD/LEGOS
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Peter Brandt
GEOMAR Helmholtz Centre for Ocean Research Kiel
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Marcus Dengler
GEOMAR Helmholtz Centre for Ocean Research Kiel
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Abstract

Multiyear turbulence measurements from oceanographic moorings in the equatorial Atlantic and Pacific cold tongues reveal similarities in deep cycle turbulence (DCT) beneath the ML and above the core of the Equatorial Undercurrent (EUC). Diurnal composites of turbulence kinetic energy dissipation rate, $\epsilon$, clearly show the diurnal cycles of turbulence beneath the ML in both cold tongues. Despite differences in surface forcing, EUC strength and core depth, DCT persists at all three sites, and is consistent between the sites. Time-mean values of $\epsilon$ at 30 m depth are nearly identical at all three sites. Variations of averaged values of $\epsilon$ in the deep cycle layer below 30 m range to a factor of 10 between sites. A proposed scaling in depth that isolates the deep cycle layers and of $\epsilon$ by the product of wind stress and current shear collapses vertical profiles at all sites to within a factor of 2.
28 Apr 2022Published in Geophysical Research Letters volume 49 issue 8. 10.1029/2021GL097345