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Title: Quantifying residual, eddy, and mean flow effects on mixing in an idealized circumpolar current

Abstract

Meridional diffusivity is assessed in this paper for a baroclinically unstable jet in a high-latitudeIdealized Circumpolar Current (ICC) using the Model for Prediction Across Scales-Ocean (MPAS-O) and the online Lagrangian In-situ Global High-performance particle Tracking (LIGHT) diagnostic via space-time dispersion of particle clusters over 120 monthly realizations of O(10 6) particles on 11 potential density surfaces. Diffusivity in the jet reaches values of O(6000 m 2 s -1) and is largest near the critical layer supporting mixing suppression and critical layer theory. Values in the vicinity of the shelf break are suppressed to O(100 m 2 s -1) due to the presence of westward slope front currents. Diffusivity attenuates less rapidly with depth in the jet than both eddy velocity and kinetic energy scalings would suggest. Removal of the mean flow via high-pass filtering shifts the nonlinear parameter (ratio of the eddy velocity to eddy phase speed) into the linear wave regime by increasing the eddy phase speed via the depth-mean flow. Low-pass filtering, in contrast, quantifies the effect of mean shear. Diffusivity is decomposed into mean flow shear, linear waves, and the residual nonhomogeneous turbulence components, where turbulence dominates and eddy-produced filamentation strained by background mean shear enhances mixing,more » accounting for ≥ 80% of the total diffusivity relative to mean shear [O(100 m 2 s -1)], linear waves [O(1000 m 2 s -1)], and undecomposed full diffusivity [O(6000 m 2 s -1)]. Finally, diffusivity parameterizations accounting for both the nonhomogeneous turbulence residual and depth variability are needed.« less

Authors:
 [1];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1369499
Alternate Identifier(s):
OSTI ID: 1360702
Report Number(s):
LA-UR-16-22765
Journal ID: ISSN 0022-3670
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Published Article
Journal Name:
Journal of Physical Oceanography
Additional Journal Information:
Journal Volume: 2017; Journal Issue: 8; Journal ID: ISSN 0022-3670
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Earth Sciences

Citation Formats

Wolfram, Phillip J., and Ringler, Todd D. Quantifying residual, eddy, and mean flow effects on mixing in an idealized circumpolar current. United States: N. p., 2017. Web. doi:10.1175/JPO-D-16-0101.1.
Wolfram, Phillip J., & Ringler, Todd D. Quantifying residual, eddy, and mean flow effects on mixing in an idealized circumpolar current. United States. doi:10.1175/JPO-D-16-0101.1.
Wolfram, Phillip J., and Ringler, Todd D. Thu . "Quantifying residual, eddy, and mean flow effects on mixing in an idealized circumpolar current". United States. doi:10.1175/JPO-D-16-0101.1.
@article{osti_1369499,
title = {Quantifying residual, eddy, and mean flow effects on mixing in an idealized circumpolar current},
author = {Wolfram, Phillip J. and Ringler, Todd D.},
abstractNote = {Meridional diffusivity is assessed in this paper for a baroclinically unstable jet in a high-latitudeIdealized Circumpolar Current (ICC) using the Model for Prediction Across Scales-Ocean (MPAS-O) and the online Lagrangian In-situ Global High-performance particle Tracking (LIGHT) diagnostic via space-time dispersion of particle clusters over 120 monthly realizations of O(106) particles on 11 potential density surfaces. Diffusivity in the jet reaches values of O(6000 m2 s-1) and is largest near the critical layer supporting mixing suppression and critical layer theory. Values in the vicinity of the shelf break are suppressed to O(100 m2 s-1) due to the presence of westward slope front currents. Diffusivity attenuates less rapidly with depth in the jet than both eddy velocity and kinetic energy scalings would suggest. Removal of the mean flow via high-pass filtering shifts the nonlinear parameter (ratio of the eddy velocity to eddy phase speed) into the linear wave regime by increasing the eddy phase speed via the depth-mean flow. Low-pass filtering, in contrast, quantifies the effect of mean shear. Diffusivity is decomposed into mean flow shear, linear waves, and the residual nonhomogeneous turbulence components, where turbulence dominates and eddy-produced filamentation strained by background mean shear enhances mixing, accounting for ≥ 80% of the total diffusivity relative to mean shear [O(100 m2 s-1)], linear waves [O(1000 m2 s-1)], and undecomposed full diffusivity [O(6000 m2 s-1)]. Finally, diffusivity parameterizations accounting for both the nonhomogeneous turbulence residual and depth variability are needed.},
doi = {10.1175/JPO-D-16-0101.1},
journal = {Journal of Physical Oceanography},
number = 8,
volume = 2017,
place = {United States},
year = {Thu Jul 13 00:00:00 EDT 2017},
month = {Thu Jul 13 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1175/JPO-D-16-0101.1

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