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  1. Recent Upgrades and Plans for the NOAA/NCEP Short Range Ensemble Forecast (SREF) SystemJeff McQueen, Jun Du, Binbin Zhou, Geoff Manikin, Brad Ferrier and Geoff DiMego Wednesday, August 20, 2014

  2. 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

  3. 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

  4. 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

  5. Radar and RASS antennas 10-m meteorological tower 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

  6. SREF Current System Physics Members Model Res (km) Levels Members Cloud Physics Convection RSM SAS 40 28 Ctl,n,p GFS physics Simple Arak-Schubert RSM RAS 40 28 n,p GFS physics Relaxed Arak-Schubert Eta-BMJ 32 60 Ctl,n,p Op Ferrier Betts-Miller-Janjic Eta-SAT 32 60 n,p Op Ferrier BMJ-moist prof Eta-KF 32 60 Ctl,n,p Op Ferrier Kain-Fritsch Eta-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

  7. 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

  8. Ensemble Products Prob. THI>75 F Mean/Spread Surface Pressure Prob. Clr Skies Mean/Spread 2m Temperature

  9. SREF Deterministic Results Surface CONUS Errors by Forecast hr (Summer 2004) 2 m Temperature Error 2 m Temperature Bias 2 m Temperature Error

  10. SREF Deterministic Results Upper-Level 48 h RMSE (June 12-July 11, 2004) U.L.Temperature U.L.Wind U.L.RH Heights

  11. SREF Probabilistic Results Spread Plots (June 12-July 11, 2004) SLP 500H 850T 850U

  12. SREF Probabilistic Results 12hPrecipitation- 0.1” threshold (June 12-July 11, 2004) 12 h qpf RPSS 12 h qpf Spread RPSS=Relative Probabilistic Skill Score

  13. SREF Probabilistic Results Ranked Histograms 63 h forecasts (June 12-July 11, 2004) Operational Experimental

  14. SREF Aviation ProjectLow Level Wind Shear Uncertainty

  15. SREF Warm Season Case StudyJuly 22, 2004 09 Z Forecast (51h Forecast) Operational Experimental Increased spread in Enhanced physics- Diversity system Precipitation Spread (inches)

  16. SREF Warm Season Case StudyJuly 22, 2004 09 Z Forecast (51h Forecast) Prob. Precip>1” in 48 h Operational Observed 48h Precip Experimental

  17. 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

  18. SREF Cold Season Case StudyFebruary 26, 2004 21 Z Run (12 h forecast) SREF 45 hr Forecast Eta-12 km 48 hr Verification

  19. SREF Cold Season Case Study ETA-BMJ ETA-KF RSM-SAS CTL CTL CTL P1 P1 P1

  20. 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

  21. Static Bias Correction: day to day rmse reduction (45h fcst) (model: RSM) SLP 500H 850T 850U 850RH 250U Oct. 3 – 10, 2004: 16 cycles

  22. Original Error (Temperature, 63hr fcst) Estimated flow-dependent bias Error after correction Error changes

  23. Summary • Deterministic results generally positive: • Significant reduction of low level errors Increased physics diversity & resolution and scaled breedingimproves 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

  24. 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)

  25. 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/

  26. WRF 24 hour 4.5 km forecast of 1 hour accumulated precipitation valid at 00Z April 21, 2004 (better than 12 hour forecasts by operational models). Verifying 2 km radar reflectivity. Courtesy Jack Kain.

  27. Eta NMM WRF: Improved cloud forecasts downwind of mountains

  28. HiResWindow Plans

  29. SREF Challenges • 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-modelEPS • (5) Improved Post processing such as bias correction, • spread and PDF calibration

  30. 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)

  31. 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)

  32. Torino OlympicsA breeding ground for Multi-center SR-EPS Evaluation 8 member multi-model,physics,bred ICs • 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

  33. BACKUPS

  34. 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)

  35. WRF/Nonhydrostatic Mesoscale ModelFeature Comparison With Meso Eta