Overview of Microphysics in NCEP Models Brad Ferrier 1,2 (Thanks to Eric Aligo 1,2 ) 1 NOAA/NWS/NCEP/EMC 2 I.M. Systems Group, Inc (IMSG) “Quick Hits” Session NCEP Production Suite Review (NPSR) NCWCP, College Park, MD 7 – 9 December 2015

Microphysics Schemes in EMC Models Model System Microphysics Scheme(s) Advected Variables Within Physics GFS, GEFSZhou/Moorthi et al. Qv, Qcld (Ice/water)Qc, Qi NAM: Parent Nests Ferrier-Aligo (F-A) Qv, Qt (Frain, Fice, RF) Qv, Qc, Qr, Qice, Qice*RF Qv, Qc, Qr, Qci, Qs+g, RF HWRF (all doms)F-AQv, Qt (Frain, Fice, RF)Qv, Qc, Qr, Qci, Qs+g, RF HiResWinF-A* in NMMB WSM6* in ARW Qv, Qt (Frain, Fice, RF) Qv, Qc, Qr, Qci, Qs, Qg Qv, Qc, Qr, Qci, Qs+g, RF Qv, Qc, Qr, Qci, Qs, Qg RAP, HRRRThompsonQv, Qc, Qr, Qci, Qs, Qg, Ni, Nr SREF (details)details Mix of F-A & WSM6 in NMMB members Mix of Thompson, WSM6, & Ferr in ARW members Dec 2015NPSR2 Qcld = Qc + Qci, Qice = Qci + Qs+g, Qt = Qc + Qr + Qice Frain, Fice are 3D storage arrays used to separate Qc, Qr, Qice from Qt WSM6* - reduced Qg production improved composite dBZ & dBZtop FA* - early version of F-A microphysics, more similar to Ferr

Rime Factor (RF)  Variable Ice Density Dec 2015NPSR3 RF=1 (Unrimed Snow) Liquid accretion (rime) RF>20 (Sleet, hail) RF ~ 2 to 5 (Rimed Snow) RF ~ 10 (Graupel)

22-h Valid at 22Z on 20 May Moore, OK Tornado A B A B A B Use of Vertical Cross Sections in Model Diagnostics Dec 2015NPSR4 “Old” NAM Microphysics F-A Microphysics Observed Reflectivity < 50 dBZ >= 55 dBZ A B A B A B

Cross Section from 1.33-km Fire WX Nest Feb 2015NCAR-FAA In-Flight Icing5 >0°C <0°C Composite Reflectivity Rimed snow (2<RF<5) Graupel (5<RF<20) Sleet (RF>20) 0°C

“ PHYSICS WHEEL OF PAIN ” Radiation Cu Scheme Sfc & PBL Grid Scale Microphysics 1.Phase & optical properties (r eff ), overlap assumptions, horizontal fractions 2.Precipitation (+ phase) and clouds 3.Subgrid transports, detrainment 4.Energy exchanges with land & ocean surfaces 5.Convection (deep & shallow), PBL evolution Dec 2015NPSR6

Additional Challenges with Ice Microphysics We don’t have full, quantitative knowledge of: – Ice nucleation & multiplication – Particle size spectra of various habits in all conditions (esp. <-40C) – Collection/breakup between colliding ice particles – Properties of rimed & mixed-habit ice; e.g. m(D), V(D) All these conditions occur within deep convection Assessing costs/benefits of more advanced schemes is challenging and it should be based on evidence rather than on “conventional wisdom” Dec 2015NPSR7

Improving Cloud Microphysics (1 of 2) Gradual build up of effective analysis tools Evaluate against remote-sensing obs – Ground-based radars + polarization – Passive & active satellite obs e.g., JCSDA-ECMWF Clouds & Precip Workshop – Large variations between advanced schemes Collaborative projects with DTC, ESRL Make use of more cloud info in U/RTMA Dec 2015NPSR8

Improving Cloud Microphysics (2 of 2) Participate in revolving Monday meetings with: – Storm Prediction Center (SPC) – severe local convective storms (mode, evolution) – Weather Prediction Center (WPC) – precipitation, winter storms, flash floods – Aviation Weather Center (AWC) – ceiling & visibility near airports, radar echo tops in transit Participate in NCEP experimental testbeds MEG briefings have also been helpful Dec 2015NPSR9

Solving The Moisture Puzzle We need to go from here… to here! Dec 2015NPSR10 “Improved processes” are not of interest to forecasters if it does not lead to improved forecasts. Additional constraints we face: Limits in available computing (improving) & bandwidth Most complex production suite in the world