subgrid-scale microphysics in ucla-larc scm with ip-hoc
DESCRIPTION
Subgrid-scale Microphysics in UCLA-LaRC SCM with IP-HOC. Anning Cheng 1 and Kuan-Man Xu 2 AS&M, Inc. Science Directorate, NASA Langley Research Center. Outline. Intermediately prognostic (IP) higher-order closure (HOC) model - PowerPoint PPT PresentationTRANSCRIPT
Subgrid-scale Microphysics in UCLA-LaRC SCM with IP-
HOC
Anning Cheng1 and Kuan-Man Xu 2
1. AS&M, Inc.
2. Science Directorate, NASA Langley Research Center
Outline
• Intermediately prognostic (IP) higher-order closure (HOC) model
• Results form UCLA-LaRC SCM, 3D-SAM LES and 2D-SAM LES with IP-HOC
• Subgrid-scale (SGS) microphysics scheme in UCLA-LaRC SCM
• Effects of the SGS microphysics scheme
2D-SAM LES (with IP-HOC) Configuration
• Domain size is 250 km• Horizontal grid size is 200 m• The 2D LES is aligned in either x
direction (Exp. U) or y direction (Exp. V)
• The rest of configuration is the same as in the 3D LES
Subgrid-scale Autoconversion
• The original Kessler’s autoconversion rate is simply proportional to the grid-mean cloud water mixing ratio, subject to a threshold value
• An integration of the Kessler’s formula multiplied by the subgrid-scale Double-Gaussian pdf found that subgrid-scale autoconversion is a function of mean, variance, and skewness of liquid water potential temperature and total water mixing ratio
What is the effect of including the new subgrid-scale autoconversion formulation?
Rain Water Collection Rate and Skewness of W
Summary and Discussion
• UCLA-LaRC SCM produces reasonable results for the RICO case although improvement is still needed
• Subgrid-scale microphysics is essential for the IP-HOC model to produce precipitation
• The cloud amount and cloud top height decreased drastically when subgrid-scale autoconversion rate was used
• Compared to 3D LES, the autoconversion rate is too high, but the collection rate is reasonable in the SCM simulation athough their formula are very simple
Thank You!