Toward the Mitigation of Spurious Cloud-Edge Supersaturation in Cloud Models

Wojciech W. Grabowski National Center for Atmospheric Research,* Boulder, Colorado

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Hugh Morrison National Center for Atmospheric Research,* Boulder, Colorado

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Abstract

This paper presents a straightforward approach to mitigate the problem of spurious cloud-edge supersaturation in high-spatial-resolution cloud models (e.g., moist large-eddy simulation models). The central idea, following a 1989 J. Atmos. Sci. paper by Grabowski, is that supersaturation predicted by the supersaturation equation should be used to adjust the temperature and moisture solutions, rather than the other way around as in the standard approach in cloud modeling, where the temperature and moisture solutions are used to diagnose the supersaturation. Details of the adjustment scheme are discussed and illustrated through simple one-dimensional tests applying a two-moment warm-rain microphysics scheme that predicts the in-cloud supersaturation. Extension of this approach to bin microphysics models is also outlined.

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

Corresponding author address: Wojciech W. Grabowski, NCAR/MMM, P.O. Box 3000, Boulder, CO 80307-3000. Email: grabow@ncar.ucar.edu

Abstract

This paper presents a straightforward approach to mitigate the problem of spurious cloud-edge supersaturation in high-spatial-resolution cloud models (e.g., moist large-eddy simulation models). The central idea, following a 1989 J. Atmos. Sci. paper by Grabowski, is that supersaturation predicted by the supersaturation equation should be used to adjust the temperature and moisture solutions, rather than the other way around as in the standard approach in cloud modeling, where the temperature and moisture solutions are used to diagnose the supersaturation. Details of the adjustment scheme are discussed and illustrated through simple one-dimensional tests applying a two-moment warm-rain microphysics scheme that predicts the in-cloud supersaturation. Extension of this approach to bin microphysics models is also outlined.

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

Corresponding author address: Wojciech W. Grabowski, NCAR/MMM, P.O. Box 3000, Boulder, CO 80307-3000. Email: grabow@ncar.ucar.edu

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  • Clark, T. L., 1973: Numerical modeling of the dynamics and microphysics of warm cumulus convection. J. Atmos. Sci., 30 , 857878.

  • Grabowski, W. W., 1989: Numerical experiments on the dynamics of the cloud-environment interface: Small cumulus in a shear-free environment. J. Atmos. Sci., 46 , 35133541.

    • Search Google Scholar
    • Export Citation
  • Grabowski, W. W., 2007: Representation of turbulent mixing and buoyancy reversal in bulk cloud models. J. Atmos. Sci., 64 , 36663680.

  • Grabowski, W. W., and P. K. Smolarkiewicz, 1990: Monotone finite difference approximations to the advection-condensation problem. Mon. Wea. Rev., 118 , 20822097.

    • Search Google Scholar
    • Export Citation
  • Hall, W. D., 1980: A detailed microphysical model within a two-dimensional framework: Model description and preliminary results. J. Atmos. Sci., 37 , 24862507.

    • Search Google Scholar
    • Export Citation
  • Klaassen, G. P., and T. L. Clark, 1985: Dynamics of the cloud-environment interface and entrainment in small cumuli: Two-dimensional simulations in the absence of ambient shear. J. Atmos. Sci., 42 , 26212642.

    • Search Google Scholar
    • Export Citation
  • Kogan, Y. L., M. P. Khairoutdinov, D. K. Lilly, Z. N. Kogan, and Q. Liu, 1995: Modeling of stratocumulus cloud layers in a large eddy simulation model with explicit microphysics. J. Atmos. Sci., 52 , 29232940.

    • Search Google Scholar
    • Export Citation
  • Margolin, L., J. M. Reisner, and P. K. Smolarkiewicz, 1997: Application of the volume-of-fluid method to the advection-condensation problem. Mon. Wea. Rev., 125 , 22652273.

    • Search Google Scholar
    • Export Citation
  • Morrison, H., and W. W. Grabowski, 2007: Comparison of bulk and bin warm-rain microphysics models using a kinematic framework. J. Atmos. Sci., 64 , 28392861.

    • Search Google Scholar
    • Export Citation
  • Morrison, H., and W. W. Grabowski, 2008: Modeling supersaturation and subgrid-scale mixing in a large-eddy model with two-moment bulk warm microphysics. J. Atmos. Sci., 65 , 792812.

    • Search Google Scholar
    • Export Citation
  • Smolarkiewicz, P. K., 1984: A fully multidimensional positive definite advection transport algorithm with small implicit diffusion. J. Comput. Phys., 54 , 325362.

    • Search Google Scholar
    • Export Citation
  • Smolarkiewicz, P. K., and T. L. Clark, 1986: The multidimensional positive definite advection transport algorithm: Further development and applications. J. Comput. Phys., 67 , 396438.

    • Search Google Scholar
    • Export Citation
  • Smolarkiewicz, P. K., and W. W. Grabowski, 1990: The multidimensional positive definite advection transport algorithm: Nonoscillatory option. J. Comput. Phys., 86 , 355375.

    • Search Google Scholar
    • Export Citation
  • Smolarkiewicz, P. K., and L. G. Margolin, 1998: MPDATA: A finite-difference solver for geophysical flows. J. Comput. Phys., 140 , 459480.

    • Search Google Scholar
    • Export Citation
  • Stevens, B., R. L. Walko, and W. R. Cotton, 1996: The spurious production of cloud-edge supersaturation by Eulerian models. Mon. Wea. Rev., 124 , 10341041.

    • Search Google Scholar
    • Export Citation
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