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