1. A “New” One-moment 4ICE Scheme for the GCE Stephen Lang, SSAI W.-K. Tao, NASA GSFC Jiundar Chern, Morgan State U. Xiaowen Li, Morgan State U. Di Wu, SSAI Xiping Zeng, Morgan State U. Toshi Matsui, ESSIC September 11, 2012 Mesoscale Atmospheric Processes Branch Laboratory Meeting

2. Lang et al. (2007) -- no dry growth, reduced snow collection efficiencies Less overall graupel, improved CFADs

3. Lang et al. (2011) -- lots of changes, added snow/graupel size mapping Lowered excessive penetration of 40 dBZ echoes, improved CFADs

4. Lang et al. (2011) applied to KWAJEX MCS Lowered excessive penetration of 40 dBZ echoes, improved CFADs

5. THE NOTCH and THE TAIL

6. Actually not really “new”….. Added hail processes from the Lin et al. (1983) 3ICE hail scheme to the improved (Lang et al. 2007, 2011) Rutledge and Hobbs (1983, 1984) 3ICE graupel scheme. Applied some lessons learned to the hail processes… Unchanged Hail riming Hail collection of ice and snow during wet growth*** Hail accretion of rain Hail deposition/sublimation Hail melting and shedding New/modified Rain freezes to hail not graupel Ice or Snow collecting rain becomes hail not graupel Hail collection of graupel during wet growth Hallett-Mossop rime splintering of hail via riming Hail transferred to graupel via deposition Omitted Hail collection of ice or snow as dry growth

7. Other modifications….. Added a snow density mapping (smaller=higher density, Heymsfield et al.) Modified the Lang et. al. 2011 graupel/snow size mapping (reduced sizes in tail) Modified the saturation adjustment: cloud ice can persist in sub-saturated air down to RHI=70% allows for a 5% background super-saturation w.r.t. ice cloud evaporation only when W > -0.1 m/s (limit spurious evaporation, Reisner) Added “physical” rain evaporation correction based on bin (Li et al. 2010) but with limits Added two-tier graupel density scheme (0.3 0.5) including fall speeds

8. Snow size/density mapping  snow = 0.1 g/m 3  snow = 0.05 g/m 3

9. Graupel size mapping  graupel = 0.4 g/m 3  graupel = 0.3 g/m 3  graupel = 0.5 g/m 3

10. Maximum Reflectivity

11. Reflectivity CFADs

12. Hydrometeor Profiles

15. Summary and Future Plans The 4ICE scheme improves the GCE’s radar signature in two ways: 1) it eliminates the occurrence of elevated reflectivity maxima (most likely via higher hail fall speeds) and could perhaps even help in less intense cases, and 2) with its ability to produce high reflectivity values, it eliminates the need for graupel and snow to produce those values, allowing for more “stable” snow/graupel size mappings and mappings better suited to produce reflectivity values with the highest occurrence. Test and refine the rain evaporation correction, transfer of hail/graupel to snow, and changes to the saturation adjustment. Test the 4ICE scheme in WRF and the MMF to make sure it works well in a variety of environments. Validate with radar CFADs and hydrometeor classifications for a variety of cases. Use CloudSat or other similar instrument(s) to get a better picture of cloud top performance with PDFs. Validate/modify snow/graupel size/density maps using in situ and/or bin data.