Editorial Type:
Article
Article Type:
Research Article

A Closure for Updraft–Downdraft Representation of Subgrid-Scale Fluxes in Cloud-Resolving Models

Chin-Hoh Moeng National Center for Atmospheric Research,* Boulder, Colorado

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Print Publication:
01 Feb 2014
DOI:
https://doi.org/10.1175/MWR-D-13-00166.1
Page(s):
703–715
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Abstract

A closure relationship between subgrid-scale (SGS) updraft–downdraft differences and resolvable-scale (RS) variables is proposed and tested for cloud-resolving models (CRMs), based on a data analysis of a large-eddy simulation (LES) of deep convection. The LES flow field is partitioned into CRM-RS and CRM-SGS using a cutoff scale that corresponds to a typical CRM grid resolution. This study first demonstrates the capability of an updraft–downdraft model framework in representing the SGS fluxes of heat, moisture, and momentum over the entire deep convection layer. It then formulates a closure scheme to relate SGS updraft–downdraft differences to horizontal gradients of RS variables. The closure is based on the idea that largest SGS and smallest RS motions are spectrally linked and hence their horizontal fluctuations must be strongly communicated. This relation leads to an SGS scheme that expresses vertical SGS fluxes in terms of horizontal gradients of RS variables, which differs from conventional downgradient eddy diffusivity models. The new scheme is shown to better represent the forward and backscatter energy transfer between CRM-RS and CRM-SGS components than conventional eddy-viscosity models.

The National Center for Atmospheric Research is sponsored by the National Science Foundation.

Corresponding author address: Chin-Hoh Moeng, MMM Division, NCAR, Boulder, CO 80307-3000. E-mail: moeng@ucar.edu

Abstract

A closure relationship between subgrid-scale (SGS) updraft–downdraft differences and resolvable-scale (RS) variables is proposed and tested for cloud-resolving models (CRMs), based on a data analysis of a large-eddy simulation (LES) of deep convection. The LES flow field is partitioned into CRM-RS and CRM-SGS using a cutoff scale that corresponds to a typical CRM grid resolution. This study first demonstrates the capability of an updraft–downdraft model framework in representing the SGS fluxes of heat, moisture, and momentum over the entire deep convection layer. It then formulates a closure scheme to relate SGS updraft–downdraft differences to horizontal gradients of RS variables. The closure is based on the idea that largest SGS and smallest RS motions are spectrally linked and hence their horizontal fluctuations must be strongly communicated. This relation leads to an SGS scheme that expresses vertical SGS fluxes in terms of horizontal gradients of RS variables, which differs from conventional downgradient eddy diffusivity models. The new scheme is shown to better represent the forward and backscatter energy transfer between CRM-RS and CRM-SGS components than conventional eddy-viscosity models.

The National Center for Atmospheric Research is sponsored by the National Science Foundation.

Corresponding author address: Chin-Hoh Moeng, MMM Division, NCAR, Boulder, CO 80307-3000. E-mail: moeng@ucar.edu
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  • Arakawa, A., and W. H. Schubert, 1974: Interaction of a cumulus cloud ensemble with the large-scale environment, Part I. J. Atmos. Sci., 31, 674–701.

    • Search Google Scholar
    • Export Citation

  • Bardina, J., J. H. Ferziger, and W. C. Reynolds, 1980: Improved subgrid-scale models for large-eddy simulation. American Institute for Aeronautics and Astronautics Paper 80-1357, 10 pp.

  • Bogenschutz, P. A., S. K. Krueger, and M. Khairoutdinov, 2010: Assumed probability density functions for shallow and deep convection. J. Adv. Model. Earth Syst.,2, doi:10.3894/JAMES.2010.2.10, 24 pp.

  • Chow, F. K., R. L. Street, M. Xue, and J. H. Ferziger, 2005: Explicit filtering and reconstruction turbulence modeling for large-eddy simulation of neutral boundary layer flow. J. Atmos. Sci., 62, 2058–2077.

    • Search Google Scholar
    • Export Citation

  • Germano, M., 1986: A proposal for a redefinition of the turbulent stresses in the filtered Navier-Stokes equations. Phys. Fluids, 29, 2323–2324.

    • Search Google Scholar
    • Export Citation

  • Khairoutdinov, M. F., S. K. Krueger, C.-H. Moeng, P. A. Bogenschutz, and D. A. Randall, 2009: Large-eddy simulation of maritime deep tropical convection. J. Adv. Model. Earth Syst.,1, doi:10.3894/JAMES.2009.1.15, 13 pp.

  • LeMone, M. A., and E. J. Zipser, 1980: Cumulonimbus vertical velocity events in GATE. Part I: Diameter, intensity, and mass flux. J. Atmos. Sci., 37, 2444–2457.

    • Search Google Scholar
    • Export Citation

  • Leonard, A., 1974: Energy cascade in large eddy simulations of turbulent fluid flows. Advances in Geophysics, Vol. 18, Academic Press, 237–248.

    • Search Google Scholar
    • Export Citation

  • Lu, H., and F. Porte-Agel, 2010: A modulated gradient model for large-eddy simulation: Application to a neutral atmospheric boundary layer. Phys. Fluids, 22, 015109, doi:10.1063/1.3291073.

    • Search Google Scholar
    • Export Citation

  • Meneveau, C., and J. Katz, 2000: Scale-invariance and turbulence models for large-eddy simulation. Annu. Rev. Fluid Mech., 32, 1–32.

  • Moeng, C.-H., and A. Arakawa, 2012: Representation of boundary-layer moisture transport in cloud-resolving models. Mon. Wea. Rev., 140, 3682–3698.

    • Search Google Scholar
    • Export Citation

  • Moeng, C.-H., M. A. LeMone, M. F. Khairoutdinov, S. K. Krueger, P. A. Bogenschutz, and D. A. Randall, 2009: The tropical marine boundary layer under a deep convection system: A large-eddy simulation study. J. Adv. Model. Earth Syst.,1, doi:10.3894/JAMES.2009.1.16, 13 pp.

  • Moeng, C.-H., P. P. Sullivan, M. F. Khairoutdinov, and D. A. Randall, 2010: A mixed scheme for subgrid-scale fluxes in cloud-resolving models. J. Atmos. Sci., 67, 3692–3705.

    • Search Google Scholar
    • Export Citation

  • Piomelli, U., P. Moin, and J. H. Ferziger, 1988: Model consistency in large eddy simulation of turbulent channel flows. Phys. Fluids, 31, 1884–1891.

    • Search Google Scholar
    • Export Citation

  • Piomelli, U., W. H. Cabot, P. Moin, and S. Lee, 1991: Subgrid-scale backscatter in turbulent and transitional flows. Phys. Fluids,3A, 1766–1771.

  • Siebesma, A. P., and J. W. M. Cuijpers, 1995: Evaluation of parametric assumptions for shallow cumulus convection. J. Atmos. Sci., 52, 650–666.

    • Search Google Scholar
    • Export Citation

  • Sullivan, P. P., T. W. Horst, D. H. Lenschow, C.-H. Moeng, and J. C. Weil, 2003: Structure of subfilter-scale fluxes in the atmospheric surface layer with application to large-eddy simulation modelling. J. Fluid Mech., 482, 101–139.

    • Search Google Scholar
    • Export Citation

  • Wyngaard, J. C., 2010: Turbulence in the Atmosphere. Cambridge University Press, 393 pp.

  • Zang, Y., R. L. Street, and J. R. Koseff, 1993: A dynamic mixed subgrid-scale model and its application to turbulent recirculating flows. Phys. Fluids, 5A, 3186–3196.

    • Search Google Scholar
    • Export Citation

  • Zhou, Y., J. G. Brasseur, and A. Juneja, 2001: A resolvable subfilter-scale model specific to large-eddy simulation of under-resolved turbulence. Phys. Fluids, 13, 2602–2609.

    • Search Google Scholar
    • Export Citation

  • Zipser, E. J., 1977: Mesoscale and convective-scale downdrafts as distinct components of squall-line structure. Mon. Wea. Rev., 105, 1568–1589.

    • Search Google Scholar
    • Export Citation

  • Zipser, E. J., and M. A. LeMone, 1980: Cumulus vertical velocity events in GATE. Part II: Synthesis and model core structure. J. Atmos. Sci., 37, 2458–2469.

    • Search Google Scholar
    • Export Citation
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