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RECENT RESEARCH ON A MULTI-MOMENT MICROPHYSICS SCHEME FOR NUMERICAL PREDICTION OF EXTREME WEATHER . (Peter) M.K. Yau 1 Collaborators : Frederic Chosson 1 Paul Vaillancourt 2 Jason Milbrandt 2 1 McGill University, Montreal, Canada 2 Environment


  1. RECENT RESEARCH ON A MULTI-MOMENT MICROPHYSICS SCHEME FOR NUMERICAL PREDICTION OF EXTREME WEATHER . (Peter) M.K. Yau 1 Collaborators : Frederic Chosson 1 Paul Vaillancourt 2 Jason Milbrandt 2 1 McGill University, Montreal, Canada 2 Environment Canada, Meteorological Research Division (MRD), Dorval, Canada

  2. Environment Canada's NWP Model GEM (Global Environmental Multiscale) Various grid configurations: Global Variable Global Uniform • non-hydrostatic • fully compressible • semi-implicit • semi-Lagrangian • one-way self-nesting Yin-Yang Limited Area (LAM) • staggered vertical grid (Charney-Phillips) Côté et al. (1998) Mon. Wea. Rev.

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  6. Grid Sub-Monthly Numerical Prediction Systems by the End of 2013-2015 Spacing (km) Increase resolution for GDPS, REPS, RDPS +4D-Var GEPS 66 km Global National grid HRDPS EnKF 50 25 km GDPS Global REPS 15 km 4D-Var North Amer. no assim RDPS 10 km 10 North Amer. 4D-Var 2.5km HRDPS Canada 1 No assim Forecast 1 2 10 *Courtesy of Martin Charron Page 6 Length (days)

  7. Grid Sub-Monthly Numerical Prediction Systems in 2015-17 Spacing (km) High-resolution surface systems will appear 50 members GPS 30-40 km Global 10-15 km EnKF/En-Var RPS 10 km North Amer. control 10 REnKF/En-Var HRDPS 2.5km Canada En-Var 1 GEM-Surf 250 m Canada CaLDAS Forecast 1 2 10 *Courtesy of Martin Charron Page 7 Length (days)

  8. Current Microphysics in Environment Canada's forecast model GEM ( G lobal E nvironmental M ultiscale) Grid configurations: Local Regional Global Double moment Milbrandt-Yau Sundqvist Cloud Scheme Scheme

  9. The Sundqvist cloud scheme • Cloud-cover fraction diagnosed (function of RH) • Condensation occurs when RH > 80% near surface • Total condensate (cloud water/ice) predicted • Partition of cloud water and ice diagnosed • Precipitation diagnosed and falls instantly to the ground

  10. The Milbrandt-Yau microphysics scheme Six hydrometeor categories: VAPOR NU vc , VD vc NU vi , 2 liquid: cloud , rain VD vr VD vs VD vi 4 frozen: ice , snow , graupel , hail CL ci , ML ic , FZ ci CLOUD ICE CL cs CN ig CN is , CN cr , CL is Multi-moment scheme CL cr self- self- VD vh collection collection VD vg ML sr , CL sr Milbrandt and Yau (JAS 2005 a,b) RAIN SNOW CL sr CL rs Milbrandt and Yau (JAS, 2006 a,b) CL cg CL ir CL ri Gultepe and Milbrandt CL rh , CL ih ML gr ML hr, SH hr (Pure App. Geoph.,2007) CL sh CL ch Milbrandt et al. (MWR, 2008) CN sg Milbrandt et al. (MWR, 2010) CL sr -h CL sr-g GRAUPEL HAIL CL ir-g CL ir-g Dawson et al. (MWR, 2010) CN gh Morrison and Milbrandt (MWR, 2011) SEDIMENTATION Milbrandt and Morrison (JAS, 2013) SEDIMENTATION For high resolution, Scheme implemented in grid point saturation GEM-Local (Canada) gives clouds, no ARPS (U Oklahoma, US) WRF 3.2 (US) cloud fraction COAMPS (US)

  11. Future HRDPS

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  13. OBJECTIVE Develop a unified double moment, multiclass microphysical scheme that can be used on the largest possible scale range in NWP models 15km 100km LES CRM GM 30km 2.5km 100m 500m 1km 4km 10km NWP WHY? • Consistency amongst models: deterministic and probabilistic prediction systems • Decrease spin-up and more consistent background field for data assimilation • Better microphysics for coarser resolution models HOW ? multi-moment, multi-class microphysical schemes has been developed for small scales • Extend to larger spatial scales: implement subgrid cloud/precip fractions

  14. Subgrid Cloud Fraction ∞ DEFINITIONS : � = a PDF dq t 1. The cloud fraction is the fraction of the grid that is supersaturated q s 2. The cloud fraction eventually contains the cloudy species : cloud droplets, small ice particles, and snow particles (hydrometeors experiencing water vapour deposition)

  15. Subgrid Precipitation Fraction Details in Chosson et al. (2013) cloud fraction p p p = + a a a k k k clr cld Maximum- • random overlap • Precip. comes from overlying clouds

  16. Overlap assumptions p a cloud-precip. interaction microphysical processes a ∂ q OVERLAP OF PRECIPITATION ( ) c = F q q AND CLOUD FRACTIONS c r , ∂ t proc p . a cld � � ∂ q q q � � p c c = r F a � � cld , . p ∂ t a a � � proc .

  17. Intercomparison using GEM-REGIONAL Sundqvist et al. Milbrandt and Yau Milbrandt and Yau (1989) (2005) original (2005) + SCF f(T) single moment double moment + Subgrid Cloud/Precip. Fraction scheme single class six hydrometeor classes Operational 20 Dec. 2008 regional GEM Simulation 36h ∆x=15km comparison on ∆t=450 sec the last 24h

  18. Observations from CloudSat/Calipso Calipso + CloudSat = LiDAR + RaDAR + Modis (IR) = DARDAR CLOUD products (J. Delanoe, R. Hogan, 2008, 2010) vertical profiles of cloud masks, IWC, effective radius, extinction, optical thickness, ... with horizontal resolution of 1.1km vertical resolution of 60m

  19. 8 6 Intercomparison 9 3 7 5 2 4 2 3 4 6 7 8 5 9 Each DARDAR profile of each overpass is compared to the closest profile in space and time from the GEM simulations.

  20. DARDAR Sundqvist 2 3 4 6 7 8 5 9 M&Y+SCF M&Y

  21. DARDAR Sundqvist M&Y+SCF M&Y 0.0 0.125 0.25 0.375 0.5 0.625 0.75 0.875 1.0 IWC (g/m3)

  22. 8 6 IWC 9 3 7 5 2 (g/m3) 4 All Clouds Intercomparison in-cloud IWC CF (g/m3)

  23. 4. Future research a) Consolidation of ice crystal and snow categories (graupel and hail already consolidated) . a) Microphysical sub-time stepping c) Better treatment of sub-grid scale vertical motion and sedimentation d) Improve microphysics in convective parameterization scheme and proper interface between convection, microphysics, and radiation

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