Editorial Type:
Article
Article Type:
Research Article

Implementation of Prognostic Cloud Scheme for a Regional Spectral Model

Song-You Hong Environmental Modeling Center, National Centers for Environmental Prediction, Washington, D.C.

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Hann-Ming Henry Juang Environmental Modeling Center, National Centers for Environmental Prediction, Washington, D.C.

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Qingyun Zhao Environmental Modeling Center, National Centers for Environmental Prediction, Washington, D.C.

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Print Publication:
01 Oct 1998
DOI:
https://doi.org/10.1175/1520-0493(1998)126<2621:IOPCSF>2.0.CO;2
Page(s):
2621–2639
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Abstract

The purpose of this study is to develop a precipitation physics package for the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM) designed to improve the skill of precipitation forecasts. The package incorporates a prognostic grid-resolvable precipitation scheme and a subgrid-scale precipitation parameterization scheme with a convective trigger that explicitly couples boundary layer and convective precipitation processes. In this paper, the implementation of a prognostic cloud scheme for the NCEP RSM is described. A subgrid-scale precipitation parameterization scheme was described in a companion paper.

Dynamical processes such as advection and diffusion processes for liquid species are included. Eleven experiments are conducted with a grid spacing of approximately 25 km for a heavy rain case over the United States during 15–17 May 1995. Special attention is given to the setup of the prognostic grid-resolvable precipitation scheme on a spectral grid as well as the importance of dynamical processes on a mesoscale grid together with radiation feedback. Different prognostic cloud schemes, classified according to the number of predicted liquid species, are also compared.

* Current affiliation: General Sciences Corporation, Laurel, Maryland.

Corresponding author address: Dr. Song-You Hong, GSC/SAIC at NCEP/EMC, Room 207, 5200 Auth Rd., Camp Springs, MD 20746.

Abstract

The purpose of this study is to develop a precipitation physics package for the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM) designed to improve the skill of precipitation forecasts. The package incorporates a prognostic grid-resolvable precipitation scheme and a subgrid-scale precipitation parameterization scheme with a convective trigger that explicitly couples boundary layer and convective precipitation processes. In this paper, the implementation of a prognostic cloud scheme for the NCEP RSM is described. A subgrid-scale precipitation parameterization scheme was described in a companion paper.

Dynamical processes such as advection and diffusion processes for liquid species are included. Eleven experiments are conducted with a grid spacing of approximately 25 km for a heavy rain case over the United States during 15–17 May 1995. Special attention is given to the setup of the prognostic grid-resolvable precipitation scheme on a spectral grid as well as the importance of dynamical processes on a mesoscale grid together with radiation feedback. Different prognostic cloud schemes, classified according to the number of predicted liquid species, are also compared.

* Current affiliation: General Sciences Corporation, Laurel, Maryland.

Corresponding author address: Dr. Song-You Hong, GSC/SAIC at NCEP/EMC, Room 207, 5200 Auth Rd., Camp Springs, MD 20746.

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