1. Subgrid-scale Microphysics in UCLA-LaRC SCM with IP-HOC Anning Cheng 1 and Kuan-Man Xu 2 1.AS&M, Inc. 2.Science Directorate, NASA Langley Research Center

2. 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

3. 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

8. 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?

10. Rain Water Collection Rate and Skewness of W

12. 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

13. Thank You!