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Title: A Thickness-Weighted Average Perspective of Force Balance in an Idealized Circumpolar Current

Abstract

The exact, three-dimensional thickness-weighted averaged (TWA) Boussinesq equations are used to diagnose eddy-mean flow interaction in an idealized circumpolar current (ICC). The force exerted by mesoscale eddies on the TWA velocity is expressed as the divergence of the Eliassen-Palm flux tensor. Consistent with previous findings, the analysis indicates that the dynamically relevant definition of the ocean surface layer is comprised of the set of buoyancy coordinates that ever reside at the ocean surface at a given horizontal position. The surface layer is found to be a physically distinct object with a diabatic- and force-balance that is largely isolated from the underlying adiabatic region in the interior. Within the ICC surface layer, the TWA meridional velocity is southward/northward in the top/bottom half, and has a value near zero at the bottom. In the top half of the surface layer, the zonal forces due to wind stress and meridional advection of potential vorticity act to accelerate the TWA zonal velocity; equilibrium is obtained by eddies decelerating the zonal flow via a downward flux of eastward momentum that increases with depth. In the bottom half of the surface layer, the accelerating force of the wind stress is balanced by the eddy force andmore » meridional advection of potential vorticity. The bottom of the surface layer coincides with the location where the zonal eddy force, meridional advection of potential vorticity and zonal wind stress force are all zero. The net meridional transport, Sf, within the surface layer is a small residual of its southward and northward TWA meridional flows. Furthermore, the mean meridional gradient of surface-layer buoyancy is advected by Sf to balance the surface buoyancy fluxs.« less

Authors:
 [1];  [1];  [1];  [1]
  1. Fluid Dynamics and Solid Mechanics, Los Alamos National Laboratory, Los Alamos, New Mexico
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)
OSTI Identifier:
1341332
Alternate Identifier(s):
OSTI ID: 1335630
Report Number(s):
LA-UR-16-22514
Journal ID: ISSN 0022-3670
Grant/Contract Number:  
AC52-06NA25396
Resource Type:
Published Article
Journal Name:
Journal of Physical Oceanography
Additional Journal Information:
Journal Name: Journal of Physical Oceanography Journal Volume: 47 Journal Issue: 2; Journal ID: ISSN 0022-3670
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Earth Sciences

Citation Formats

Ringler, Todd, Saenz, Juan A., Wolfram, Phillip J., and Van Roekel, Luke. A Thickness-Weighted Average Perspective of Force Balance in an Idealized Circumpolar Current. United States: N. p., 2017. Web. doi:10.1175/JPO-D-16-0096.1.
Ringler, Todd, Saenz, Juan A., Wolfram, Phillip J., & Van Roekel, Luke. A Thickness-Weighted Average Perspective of Force Balance in an Idealized Circumpolar Current. United States. https://doi.org/10.1175/JPO-D-16-0096.1
Ringler, Todd, Saenz, Juan A., Wolfram, Phillip J., and Van Roekel, Luke. Thu . "A Thickness-Weighted Average Perspective of Force Balance in an Idealized Circumpolar Current". United States. https://doi.org/10.1175/JPO-D-16-0096.1.
@article{osti_1341332,
title = {A Thickness-Weighted Average Perspective of Force Balance in an Idealized Circumpolar Current},
author = {Ringler, Todd and Saenz, Juan A. and Wolfram, Phillip J. and Van Roekel, Luke},
abstractNote = {The exact, three-dimensional thickness-weighted averaged (TWA) Boussinesq equations are used to diagnose eddy-mean flow interaction in an idealized circumpolar current (ICC). The force exerted by mesoscale eddies on the TWA velocity is expressed as the divergence of the Eliassen-Palm flux tensor. Consistent with previous findings, the analysis indicates that the dynamically relevant definition of the ocean surface layer is comprised of the set of buoyancy coordinates that ever reside at the ocean surface at a given horizontal position. The surface layer is found to be a physically distinct object with a diabatic- and force-balance that is largely isolated from the underlying adiabatic region in the interior. Within the ICC surface layer, the TWA meridional velocity is southward/northward in the top/bottom half, and has a value near zero at the bottom. In the top half of the surface layer, the zonal forces due to wind stress and meridional advection of potential vorticity act to accelerate the TWA zonal velocity; equilibrium is obtained by eddies decelerating the zonal flow via a downward flux of eastward momentum that increases with depth. In the bottom half of the surface layer, the accelerating force of the wind stress is balanced by the eddy force and meridional advection of potential vorticity. The bottom of the surface layer coincides with the location where the zonal eddy force, meridional advection of potential vorticity and zonal wind stress force are all zero. The net meridional transport, Sf, within the surface layer is a small residual of its southward and northward TWA meridional flows. Furthermore, the mean meridional gradient of surface-layer buoyancy is advected by Sf to balance the surface buoyancy fluxs.},
doi = {10.1175/JPO-D-16-0096.1},
journal = {Journal of Physical Oceanography},
number = 2,
volume = 47,
place = {United States},
year = {Thu Jan 26 00:00:00 EST 2017},
month = {Thu Jan 26 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
https://doi.org/10.1175/JPO-D-16-0096.1

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