• Andrews, D. G., and M. E. McIntyre, 1976: Planetary waves in horizontal and vertical shear: The generalized Eliassen–Palm relation and the mean zonal acceleration. J. Atmos. Sci.,33, 2031–2048.

  • ——, J. R. Holton, and C. B. Leovy, 1987: Middle Atmosphere Dynamics. Academic Press, 489 pp.

  • Bryan, K., S. Manabe, and R. C. Pacanowski, 1975: A global ocean–atmosphere climate model. Part II: The oceanic circulation. J. Phys. Oceanogr.,5, 30–46.

  • Cox, M. D., 1987: Isopycnal diffusion in a z-coordinate ocean model. Ocean Modelling (unpublished manuscript), 74, 1–3.

  • Danabasoglu, G., and J. C. McWilliams, 1995: Sensitivity of the global ocean circulation to parameterizations of mesoscale tracer transports. J. Climate,8, 2967–2987.

  • ——, ——, and P. R. Gent, 1994: The role of mesoscale tracer transports in the global ocean circulation. Science,264, 1123–1126.

  • Davis, R. E., 1994: Diapycnal mixing in the ocean: the Osborn-Cox model. J. Phys. Oceanogr.,24, 2560–2576.

  • Döös, K., and D. J. Webb, 1994: The Deacon Cell and the other meridional cells of the southern ocean. J. Phys. Oceanogr.,24, 429–442.

  • Eady, E. T., 1949: Long waves and cyclone waves. Tellus,1 (3), 33–52.

  • FRAM Group, 1991: An eddy-resolving model of the southern ocean. Eos, Trans. Amer. Geophys. Union,72, 169–175.

  • Garner, S. T., N. Nakamura, and I. M. Held, 1992: Nonlinear equilibration of two-dimensional Eady waves: A new perspective. J. Atmos. Sci.,49, 1984–1996.

  • Gent, P. R., and J. C. McWilliams, 1990: Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr.,20, 150–155.

  • ——, and ——, 1996: Eliassen–Palm fluxes and the momentum equation in non-eddy-resolving ocean circulation models. J. Phys. Oceanogr.,26, 2540–2546.

  • ——, J. Willebrand, T. J. McDougall, and J. C. McWilliams, 1995: Parameterizing eddy-induced tracer transports in ocean circulation models. J. Phys. Oceanogr.,25, 463–474.

  • Gill, A. E., 1982: Atmosphere–Ocean Dynamics. Academic Press, 662 pp.

  • Green, J. S. A., 1970: Transfer properties of the large-scale eddies and the general circulation of the atmosphere. Quart. J. Roy. Meteor. Soc.,96, 157–185.

  • Griffies, S. M., 1998: The Gent–McWilliams skew flux. J. Phys. Oceanogr.,28, 831–841.

  • Killworth, P. D., 1997: On the parameterization of eddy transfer. Part I: Theory. J. Mar. Res.,55, 1171–1197.

  • Lee, M. M., D. P. Marshall, and R. G. Williams, 1997: On the eddy transfer of tracers: Advective of diffusive? J. Mar. Res.,55, 1–24.

  • McDougall, T. J., and P. C. McIntosh, 1996: The temporal-residual-mean velocity. Part I: Derivation and the scalar conservation equations. J. Phys. Oceanogr.,26, 2653–2665.

  • McWilliams, J. C., and P. R. Gent, 1994: The wind-driven ocean circulation with an isopycnal thickness parameterization. J. Phys. Oceanogr.,24, 46–65.

  • ——, G. Danabasoglu, and P. R. Gent, 1996: Tracer budgets in the warm water sphere. Tellus,48A, 179–192.

  • Osborn, T. R., and C. S. Cox, 1972: Oceanic fine structure. Geophys. Fluid Dyn.,3, 321–345.

  • Pacanowski, R. C., 1995: MOM 2 documentation user’s guide and reference manual. GFDL Ocean Tech. Rep. 3, GFDL/NOAA, Princeton, NJ, 232 pp. [Available from GFDL/NOAA, P.O. Box 308, Princeton, NJ 08542-0308.].

  • Pedlosky, J., 1987: Geophysical Fluid Dynamics. 2d ed. Springer-Verlag, 710 pp.

  • Plumb, R. A., and J. D. Mahlman, 1987: The zonally averaged transport characteristics of the GFDL general circulation/transport model. J. Atmos. Sci.,44, 298–327.

  • Rix, N. H., and J. Willebrand, 1996: Parameterization of mesoscale eddies as inferred from a high-resolution circulation model. J. Phys. Oceanogr.,26, 2281–2285.

  • Samelson, R., 1993: Linear instability of a mixed-layer front. J. Geophys. Res.,98, 10 195–10 204.

  • Semtner, A. J., 1986: Finite-difference formulation of a world ocean model. Proceedings of the NATO Advanced Physical Oceanographic Numerical Modelling. J. J. O’Brien, Ed., D. Riedel, 187–202.

  • ——, and R. M. Chervin, 1992: Ocean general circulation from a global eddy-resolving model. J. Geophys. Res.,97, 5493–5550.

  • Stone, P. H., 1972: A simplified radiative-dynamical model for the static stability of rotating atmospheres. J. Atmos. Sci.,29, 405–418.

  • Tandon, A., and C. Garrett, 1996: On a recent parameterization of mesoscale eddies. J. Phys. Oceanogr.,26, 406–411.

  • Treguier, A. M., I. M. Held, and V. D. Larichev, 1997: Parameterization of quasigeostrophic eddies in primitive equation models. J. Phys. Oceanogr.,27, 567–580.

  • Visbeck, M., J. Marshall, T. Haine, and M. Spall, 1997: On the specification of eddy transfer coefficients in coarse resolution ocean circulation models. J. Phys. Oceanogr.,27, 381–402.

  • Williams, G. P., 1971: Baroclinic annulus waves. J. Fluid Mech.,49, 417–449.

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The Influence of Mesoscale Eddies on Coarsely Resolved Density: An Examination of Subgrid-Scale Parameterization

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  • 1 Physical Oceanography Research Division, Scripps Institution of Oceanography, La Jolla, California
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Abstract

Coarse-resolution numerical models of ocean circulation rely on parameterizations of unresolved mesoscale eddy effects. In order to investigate the role of eddy-flux divergences in the density equation, the GFDL Modular Ocean Model (MOM) has been configured as a simple flat-bottomed channel model with sufficient resolution to represent mesoscale eddies. Eady-type baroclinic instability and a wind-forced channel have been considered. As an analog to the large-scale components addressed by low-resolution models, the influence of eddy fluxes on the zonal-mean density field was evaluated. Results show that eddy-flux divergences are larger than mean-flux divergences. The effect of mesoscale eddies on the mean density field is often hypothesized to take an advective form that conserves mean density so that eddy effects are adiabatic in the zonal mean. However, in both of the examples studied a significant component of the mesoscale eddy effect on the zonal mean is diabatic and makes mean density nonconservative. The associated diapycnal fluxes result from zonally averaging terms representing processes that are locally adiabatic.

Subgrid-scale parameterizations (such as eddy diffusion) represent the unresolved eddy-flux divergence as a function of the resolved density field. The authors computed optimal coefficients for a variety of parameterizations and evaluated their skill. When the model output is time-averaged, quasi-adiabatic parameterizations, such as the one proposed by Gent and McWilliams, are able to explain as much as 43% of the mean-squared eddy-flux divergence. However, for shorter averaging periods or instantaneous snapshots, even for the spatially averaged model fields, parameterization skill drops.

Corresponding author address: Dr. Sarah Gille, Department of Earth System Science, University of California, Irvine, Irvine, CA 92697-3100.

Email: sgille@uci.edu

Abstract

Coarse-resolution numerical models of ocean circulation rely on parameterizations of unresolved mesoscale eddy effects. In order to investigate the role of eddy-flux divergences in the density equation, the GFDL Modular Ocean Model (MOM) has been configured as a simple flat-bottomed channel model with sufficient resolution to represent mesoscale eddies. Eady-type baroclinic instability and a wind-forced channel have been considered. As an analog to the large-scale components addressed by low-resolution models, the influence of eddy fluxes on the zonal-mean density field was evaluated. Results show that eddy-flux divergences are larger than mean-flux divergences. The effect of mesoscale eddies on the mean density field is often hypothesized to take an advective form that conserves mean density so that eddy effects are adiabatic in the zonal mean. However, in both of the examples studied a significant component of the mesoscale eddy effect on the zonal mean is diabatic and makes mean density nonconservative. The associated diapycnal fluxes result from zonally averaging terms representing processes that are locally adiabatic.

Subgrid-scale parameterizations (such as eddy diffusion) represent the unresolved eddy-flux divergence as a function of the resolved density field. The authors computed optimal coefficients for a variety of parameterizations and evaluated their skill. When the model output is time-averaged, quasi-adiabatic parameterizations, such as the one proposed by Gent and McWilliams, are able to explain as much as 43% of the mean-squared eddy-flux divergence. However, for shorter averaging periods or instantaneous snapshots, even for the spatially averaged model fields, parameterization skill drops.

Corresponding author address: Dr. Sarah Gille, Department of Earth System Science, University of California, Irvine, Irvine, CA 92697-3100.

Email: sgille@uci.edu

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