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Title: Nonlocal Transport and Implied Viscosity and Diffusivity throughout the Boundary Layer in LES of the Southern Ocean with Surface Waves

Abstract

Abstract Observations from the Southern Ocean Flux Station provide a wide range of wind, buoyancy, and wave (Stokes) forcing for large-eddy simulation (LES) of deep Southern Ocean boundary layers. Almost everywhere there is a nonzero angle Ω between the shear and the stress vectors. Also, with unstable forcing there is usually a depth where there is stable stratification, but zero buoyancy flux and often a number of depths above where there is positive flux, but neutral stratification. These features allow nonlocal transports of buoyancy and of momentum to be diagnosed, using either the Eulerian or Lagrangian shear. The resulting profiles of nonlocal diffusivity and viscosity are quite similar when scaled according to Monin–Obukhov similarity theory in the surface layer, provided the Eulerian shear is used. Therefore, a composite shape function is constructed that may be generally applicable. In contrast, the deeper boundary layer appears to be too decoupled from the Stokes component of the Lagrangian shear. The nonlocal transports can be dominant. The diagnosed across-shear momentum flux is entirely nonlocal and is highly negatively correlated with the across-shear component of the wind stress, just as nonlocal and surface buoyancy fluxes are related. Furthermore, in the convective limit the scaling coefficientsmore » become essentially identical, with some consistency with atmospheric experience. The nonlocal contribution to the along-shear momentum flux is proportional to (1 − cosΩ) and is always countergradient, but is unrelated to the aligned wind stress component.« less

Authors:
 [1];  [1];  [1]
  1. National Center for Atmospheric Research, Boulder, Colorado
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1569093
Alternate Identifier(s):
OSTI ID: 1577833
Grant/Contract Number:  
SC-00126005; AC02-05CH11231
Resource Type:
Published Article
Journal Name:
Journal of Physical Oceanography
Additional Journal Information:
Journal Name: Journal of Physical Oceanography Journal Volume: 49 Journal Issue: 10; Journal ID: ISSN 0022-3670
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Oceanography

Citation Formats

Large, William G., Patton, Edward G., and Sullivan, Peter P. Nonlocal Transport and Implied Viscosity and Diffusivity throughout the Boundary Layer in LES of the Southern Ocean with Surface Waves. United States: N. p., 2019. Web. doi:10.1175/JPO-D-18-0202.1.
Large, William G., Patton, Edward G., & Sullivan, Peter P. Nonlocal Transport and Implied Viscosity and Diffusivity throughout the Boundary Layer in LES of the Southern Ocean with Surface Waves. United States. doi:10.1175/JPO-D-18-0202.1.
Large, William G., Patton, Edward G., and Sullivan, Peter P. Thu . "Nonlocal Transport and Implied Viscosity and Diffusivity throughout the Boundary Layer in LES of the Southern Ocean with Surface Waves". United States. doi:10.1175/JPO-D-18-0202.1.
@article{osti_1569093,
title = {Nonlocal Transport and Implied Viscosity and Diffusivity throughout the Boundary Layer in LES of the Southern Ocean with Surface Waves},
author = {Large, William G. and Patton, Edward G. and Sullivan, Peter P.},
abstractNote = {Abstract Observations from the Southern Ocean Flux Station provide a wide range of wind, buoyancy, and wave (Stokes) forcing for large-eddy simulation (LES) of deep Southern Ocean boundary layers. Almost everywhere there is a nonzero angle Ω between the shear and the stress vectors. Also, with unstable forcing there is usually a depth where there is stable stratification, but zero buoyancy flux and often a number of depths above where there is positive flux, but neutral stratification. These features allow nonlocal transports of buoyancy and of momentum to be diagnosed, using either the Eulerian or Lagrangian shear. The resulting profiles of nonlocal diffusivity and viscosity are quite similar when scaled according to Monin–Obukhov similarity theory in the surface layer, provided the Eulerian shear is used. Therefore, a composite shape function is constructed that may be generally applicable. In contrast, the deeper boundary layer appears to be too decoupled from the Stokes component of the Lagrangian shear. The nonlocal transports can be dominant. The diagnosed across-shear momentum flux is entirely nonlocal and is highly negatively correlated with the across-shear component of the wind stress, just as nonlocal and surface buoyancy fluxes are related. Furthermore, in the convective limit the scaling coefficients become essentially identical, with some consistency with atmospheric experience. The nonlocal contribution to the along-shear momentum flux is proportional to (1 − cosΩ) and is always countergradient, but is unrelated to the aligned wind stress component.},
doi = {10.1175/JPO-D-18-0202.1},
journal = {Journal of Physical Oceanography},
number = 10,
volume = 49,
place = {United States},
year = {2019},
month = {10}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1175/JPO-D-18-0202.1

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