Implementation of prognostic cloud scheme for a Regional Spectral Model

• Published in: Monthly weather review 1998-10, Vol.126 (10), p.2621-2639
• Main Authors: HONG, S.-Y, JUANG, H.-M. H, QINGYUN ZHAO
• Format: Article
• Language: English
• Subjects: Earth, ocean, space; Exact sciences and technology; External geophysics; Meteorology; Weather analysis and prediction
• ISSN: 0027-0644; 1520-0493
• DOI: 10.1175/1520-0493(1998)126<2621:iopcsf>2.0.co;2

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.