Article Type:
Research Article

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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Print Publication:
01 Mar 2008
DOI:
https://doi.org/10.1175/2007MWR2283.1
Page(s):
1224–1234
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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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