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Recent Upgrades and Plans for the NOAA/NCEP Short Range Ensemble Forecast (SREF) System Jeff McQueen, Jun Du, Binbin Zhou, Geoff Manikin, Brad Ferrier and Geoff DiMego Wednesday, August 20, 2014. SREF Team. System Integration/Operations : Jun Du Physics Diversity Configuration: B. Ferrier - PowerPoint PPT Presentation
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Recent Upgrades and Plans for the NOAA/NCEP Short Range Ensemble
Forecast (SREF) System
Jeff McQueen, Jun Du, Binbin Zhou, Geoff Manikin, Brad Ferrier and Geoff DiMego
Saturday, April 22, 2023
SREF Team• System Integration/Operations: Jun Du
• Physics Diversity Configuration: B. Ferrier
• Product Generation/Visualization:• Standard Suite: Binbin Zhou, Jun Du• Aviation, Energy: Binbin Zhou• Severe Weather: G. Manikin, D. Bright
• Verification:– Model to Observations (Det/Prob): H. Chuang– Model to analysis (Det/Prob): B. Zhou– Case Studies: G. Manikin, R. Grumm
• Calibration:– Bias Correction: J. Du, B. Coi– Bayesian Model Averaging: Mark Raulston
• High Res Ensembles (WRF): G. DiMego, D. Jovic, E. Rogers, H. Chuang
• Ensemble Transforms (Future): M. Wei, Z. Toth
• Training: B. Bua
Outline
• Improved SR-Ensemble Prediction Systems– NCEP Short Range Ensemble Forecasts (SREF)– High Resolution Window Weather Reseach and Forecast
System (WRF) Ensemble
• Improved Deterministic and Probabilistic Products– Higher Fidelity Capture smaller scale features– Improved Accuracy– Improved probabilistic information to help quantify forecast
uncertainties– Bias Correction and Bayesian Model Averaging– Visualization– Verification
Ensemble Modeling System Goals
• Improved probabilistic products for NWS mission forecasts (Severe storms, Aviation, Hydromet, ocean, tropical, Energy, Dispersion)
• Quantify Uncertainty for Each Forecast Run– High Confidence= good agreement between forecasts?
• Improved Spread-Skill relationship Information – System variance ~ System Mean Squared Error– Less clustering among ensemble members(more spread)
• Improved or similar skill as determined from ensemble mean and probabilistic skill scores for 1-3 day forecasts (Skill scores, Sharpness of probabilistic forecast) :– Temperatures, winds, moisture– Precipitation– Upper-level winds, heights
Recent SREF Improvements• Increased Resolution
• 48 km to 32 km horizontal resolution
• Increased to 60 levels in Eta model Members
• Enhance SREF Physics Diversity
• Various Cloud Physics and Convective Parameterization Schemes
• Scaled Breeding System
• Control Unrealistically Large Initial Condition (IC) Perturbations in cold season
• Increase IC perturbations in warm season
• Upgrade 10 Eta members to latest operational version (Impr. Land sfc model, cloud-rad effects)
• Upgrade 5 Regional Spectral Model (RSM) Members with GFS Physics and Computational Schemes
Radar and RASS antennas
10-m meteorological tower
SREF Current SystemPhysics Members
Model Res (km) Levels Members Cloud Physics ConvectionRSM SAS 40 28 Ctl,n,p GFS physics Simple Arak-SchubertRSM RAS 40 28 n,p GFS physics Relaxed Arak-Schubert
Eta-BMJ 32 60 Ctl,n,p Op Ferrier Betts-Miller-JanjicEta-SAT 32 60 n,p Op Ferrier BMJ-moist prof
Eta-KF 32 60 Ctl,n,p Op Ferrier Kain-FritschEta-KFD 32 60 n,p Op Ferrier Kain-Fritsch
with enhanced detrainment
Adjust conv. Params to account for known biases:e.g: Biases in Convective initiation timing
Implemented into NCEP Operations on August 17, 2004
Corrections to Improve Initial System Performance
• Run reduced physics-diversity system & evaluate Modified SREF system:
• Develop and test scaled IC breeding code– breeding perturbation using WRF scaled perturbation
system. Used average 850 mb T standard deviation (0.5 C) to scale IC perturbations.
– IC perturbation scale = 0.5/ – Where =Fneg-Fpos of the 12 hour domain avg 850 mb T
forecast
Ensemble ProductsProb. THI>75 F
Mean/Spread 2m Temperature
Mean/Spread Surface Pressure
Prob. Clr Skies
SREF Deterministic Results Surface CONUS Errors by Forecast hr (Summer 2004)
2 m TemperatureError
2 m TemperatureBias
2 m TemperatureError
SREF Deterministic Results Upper-Level 48 h RMSE (June 12-July 11, 2004)
U.L.TemperatureU.L.Wind
U.L.RH Heights
SLP 500H
850T 850U
SREF Probabilistic Results Spread Plots (June 12-July 11, 2004)
SREF Probabilistic Results 12h Precipitation- 0.1” threshold (June 12-July 11, 2004)
12 h qpfRPSS
12 h qpfSpread
RPSS=Relative Probabilistic Skill Score
Operational Experimental
SREF Probabilistic Results Ranked Histograms 63 h forecasts (June 12-July 11, 2004)
SREF Aviation ProjectLow Level Wind Shear Uncertainty
SREF Warm Season Case StudyJuly 22, 2004 09 Z Forecast (51h Forecast)
Increased spread in Enhanced physics-Diversity system
Operational
Experimental
Precipitation Spread (inches)
SREF Warm Season Case StudyJuly 22, 2004 09 Z Forecast (51h Forecast)
Prob. Precip>1” in 48 h
Operational
Experimental
Observed 48h Precip
SREF Warm Season Case StudyJuly 25, 2004 09 Z Run (12 h forecast)
SREF-48 km SREF-32 w/ Physics Diversity
20C 2m Temp 20C 2m Temp
SREF Cold Season Case StudyFebruary 26, 2004 21 Z Run (12 h forecast)
SREF 45 hr Forecast
Verification
Eta-12 km 48 hr
SREF Cold Season Case Study
ETA-BMJ ETA-KF RSM-SAS
CTL CTL CTL
P1 P1 P1
Improved System Postprocessing
Bias Correction• Simple running average correction based on
previous week error• Regime Dependent Correction:
– Weight corrections for each day based on current forecast’s correlation w/ previous forecast errors
Bayesian Model Averaging• Calibrate system PDF (variance) by training and
weighting ind. Member PDF• Train member PDF against observations for past
month
Static Bias Correction: day to day rmse reduction (45h fcst)
SLP 500H
850T 850U
250U 850RH
(model: RSM)
Oct. 3 – 10, 2004: 16 cycles
Original Error (Temperature, 63hr fcst) Estimated flow-dependent bias
Error after correction Error changes
Summary• Deterministic results generally positive:
– Significant reduction of low level errors Increased physics diversity & resolution and scaled breeding improves system spread
– Improved Diversity• Strongest impact on sensible wx and in Warm Season
– Additional scenarios captured – Initial Condition perturbations capture synoptic
scale uncertainties well
• Scaled breeding controls unrealistic system spread
Weather Research and Forecasting
• End-to-end Common Modeling Infrastructure– Observations and analysis
– Prediction model
– Post-processing, product generation and display
– Verification and archive
• For the community to perform research
• For operations to generate NWP guidance
• USWRP sponsorship - many partners: NCAR, NCEP, FSL, OU/CAPS, AFWA, FAA, NSF and Navy
• Initial NCEP implementation in NCEP HiResWindow (HRW) on Sept. 21, 2004
• Ensemble approach to be taken instead of single-run deterministic approach (6 member system in fy05)
HiResWindow Fixed-Domain Nested Runs
• Users want routine runs they can count on at the same time every day
• 00Z : Alaska-10 & Hawaii-8 km
• 06Z : Western-8 & Puerto Rico-8
• 12Z : Central-8 & Hawaii-8
• 18Z : Eastern-8 & Puerto Rico-8
• This gives everyone a daily high resolution run when fewer than 2 hurricane runs needed
http://www.emc.ncep.noaa.gov/mmb/mmbpll/nestpage/
WRF 24 hour 4.5 km forecast of 1 hour accumulated precipitation valid at00Z April 21, 2004 (better than 12 hour forecasts by operational models).
Verifying 2 km radar reflectivity. Courtesy Jack Kain.
Eta NMM
WRF: Improved cloud forecasts downwind of mountains
HiResWindow Plans
Hi Res Window Fire Weather IMET Support
Homeland SecurityRun
Computer Phase
8 km WRF 6 member ensemble
8 km nested WRF-NMM
4 km NMM May 2005
7 km WRF8 member ensemble
6.5 km nested WRFwith improved physics
4 km WRF Phase IIFall 2005
6 km WRF10 member ensemble
5.5 km nested in NAM-WRF run
3.5 km WRF w/ improved physics
Phase III2006
5 km WRF12 member ensemble
4.5 km nested in NAM-WRF run
3 Km WRF w/ improved physics
Phase IV2008
SREF Challenges
(1) SREF Configuration:• Impact of IC perturbations vs. model physics diversity• Physics diversity (Application dependent ?)
• Role of Land Sfc, PBL, Precip processes• Membership vs horizontal resolution
(2) Improved IC perturbations• ET, Singular Vectors, Multi-analyses
(3) Impact of lateral boundary conditions
(4) Single model EPS vs. multi-model EPS
(5) Improved Post processing such as bias correction, spread and PDF calibration
SREF Planned Upgrades 2005
System
• Run SREF 4 times per day (03, 09, 15 and 21 UTC) at ~25 km• Add 6 WRF members (some w/ GFS initial conditions)• Use Higher resolution GFS w/ MREF anomolies for SREF Lateral
Boundary Conditions
Products• Improved and new products (Convective, Aviation, Tropical, Energy) • Output SREF forecasts for Alaska and Hawaii• Add SREF mean hrly sounding BUFR files• Implement Common WRF post-processor for all members
Post Processing• Implement Grid Based Bias Correction• Develop Confidence Factors for forecasts
Verification• Improve Probabilistic NCEP Forecast Verification System (FVS)
Capabilities (event based stats)
SREF Beyond 2005• Test Global Ensemble Transform Techniques• Increase membership and diversity:
– Add Land surface, PBL perturbations– Multi-analysis IC (eg: EDAS, GSI)– 50 members, 10 km (2008)
• Regime dependent bias correction• Implement Bayesian Model Averaging• Improved Products/Applications:
– Dispersion, Air Quality– Energy, transportation
• All WRF based membership (multi-core, multi-IC, multi-physics suites)
• Relocatable High Res ensemble• VSREF: Very Short Range Ens. Forecasts for Aviation: 3
hrly updates: (6-24 h forecasts)
Torino OlympicsA breeding ground for Multi-center SR-EPS
Evaluation
• C1: WRF-NMM/Ncep Phys : Ctl, p1, n1,p2,n2
• C2: WRF-MASS/Ncar Phys: Ctl, p3,n3,p4,n4• CTL: 4 km, 1000x1000 km
• Perts: 8 km, 2000x2000 km
• Du, 2004 hybrid technique
– Add spread from perturbed members to high res ctls
• ? How much diversity given by physics diffs
• ? How much diversity given from core diffs
• ? Alternative: Multi-analysis members:– C1X, C2X initalized w/ GFS IC’s
8 member multi-model,physics,bred ICs
BACKUPS
Dissemination
• Mean, spread, probability files on NCEP FTP site
• NCEP/EMC web graphics – Mean, spread, probs, Individual members, profiles,
• NCEP/SPC Convective probabilistic products
• Mean, spread plots are being added to NCEP Operational web page
• WFO AWIPS: Scheduled for Build 7 (April 2005)
WRF/Nonhydrostatic Mesoscale ModelFeature Comparison With Meso Eta
Feature Meso Eta Model
WRF/NMM Model
Dynamics
Hydrostatic Hydrostatic plus complete nonhydrostatic corrections
Horizontal grid spacing
12 km E-grid 8 or 4 km Arakowa E-grid
Vertical coordinate
60 step-mountain eta levels
60 hybrid sigma-pressure levels
Terrain Unsmoothed silhouette with lateral boundary set to sea-level
Unsmoothed grid-cell mean everywhere