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Title: Similarity Theory in the Surface Layer of Large-Eddy Simulations of the Wind-, Wave-, and Buoyancy-Forced Southern Ocean

Journal Article · · Journal of Physical Oceanography
 [1];  [1];  [1];  [1];  [2]
  1. National Center for Atmospheric Research, Boulder, Colorado
  2. University of California, Santa Barbara, Santa Barbara, California
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In this work, Monin–Obukhov similarity theory is applied to the surface layer of large-eddy simulations (LES) of deep Southern Ocean boundary layers. Observations from the Southern Ocean Flux Station provide a wide range of wind, buoyancy, and wave (Stokes drift) forcing. Two No-Stokes LES are used to determine the extent of the ocean surface layer and to adapt the nondimensional momentum and buoyancy gradients, as functions of the stability parameter. Stokes-forced LES are used to modify this parameter for wave effects, then to formulate dependencies of Stokes similarity functions on a Stokes parameter $$ξ$$. To account for wind-wave misalignment, the dimensional analysis is extended with two independent variables, namely, the production of turbulent kinetic energy in the surface layer due to Stokes shear and the total production, so that their ratio gives $$ξ$$. Stokes forcing is shown to reduce vertical shear more than stratification, and to enhance viscosity and diffusivity by factors up to 5.8 and 4.0, respectively, such that the Prandtl number can exceed unity. A practical parameterization is developed for $$ξ$$ in terms of the meteorological forcing plus a Stokes drift profile, so that the Stokes and stability similarity functions can be combined to give turbulent velocity scales. These scales for both viscosity and diffusivity are evaluated against the LES, and the correlations are nearly 0.97. The benefit of calculating Stokes drift profiles from directional wave spectra is demonstrated by similarly evaluating three alternatives.

Research Organization:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Organization:
National Science Foundation (NSF); US Department of the Navy, Office of Naval Research (ONR); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division
Grant/Contract Number:
AC02-05CH11231; FOA-0001036; SC-00126005; N00014-16-1-2936
OSTI ID:
1556819
Alternate ID(s):
OSTI ID: 1577706
Journal Information:
Journal of Physical Oceanography, Journal Name: Journal of Physical Oceanography Vol. 49 Journal Issue: 8; ISSN 0022-3670
Publisher:
American Meteorological SocietyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 12 works
Citation information provided by
Web of Science

Cited By (2)

Argo float data and metadata from Global Data Assembly Centre (Argo GDAC) dataset January 2018
Comparing Ocean Surface Boundary Vertical Mixing Schemes Including Langmuir Turbulence journal November 2019

Figures / Tables (15)

TABLE 1(p. 5)table TABLE 1
FIG. 1(p. 6)figure FIG. 1
TABLE 2(p. 7)table TABLE 2
FIG. 2(p. 8)figure FIG. 2
FIG. 3(p. 9)figure FIG. 3
FIG. 4(p. 10)figure FIG. 4
FIG. 5(p. 12)figure FIG. 5
FIG. 6(p. 13)figure FIG. 6
FIG. 7(p. 14)figure FIG. 7
FIG. 8(p. 15)figure FIG. 8
FIG. 9(p. 15)figure FIG. 9
FIG. 10.(p. 17)figure FIG. 10.
TABLE 3(p. 18)table TABLE 3
FIG. 11(p. 19)figure FIG. 11
FIG. 12(p. 20)figure FIG. 12

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58 GEOSCIENCES
Oceanography
Ocean
Southern Ocean
Boundary layer
Langmuir circulation
Surface layer