review of emc regional ensembles: sref, narre-tl, hrrre-tl/href

Review of EMC regional ensembles: SREF, NARRE-TL, HRRRE-TL/HREF

Jun Du, Geoff DiMego, Binbin Zhou, Dusan Jovic, Bo Yang, Matt Pyle, Geoff Manikin, Brad Ferrier, Stan Benjamin (GSD) and Brian Etherton (DET)

Acknowledgements: Ensemble Team: Yuejian Zhu, Yan Luo and Bo CuiMesoscale Branch: Eric Rogers, Perry Shafran and Ying LinDTC/NCAR: Jamie WolffAWC: David BrightHPC: Dave NovakIBM: James Abeles

Content

•2011 implementations•Coming implementations•Plans

2011 implementations •Added North American domain (221 grid) SREF data on NOMADS •Added CONUS domain (212 grid) bias corrected SREF data on NOMADS•Added 4km HREF ensemble products (combining 32km SREF with 4km Hires Window runs, Du 2004)

Examples of HREF

Mean Spread Probability

01h-, 03h-, 06h-, 12h-, 24h-apcp

x x x(>0.01”,0.05”,0.1”,0.25”,0.5”,1.0”,1.5”,2”,4”,6”)

2m-T x x x(<0C, >25.5C)

10m-U x x

10m-V x x

10m-Wind x x x(>25kt, 34kt, 50kt)

2m-RH x x

CAPE x x x(>500, 1000, 2000, 3000, 4000)

CIN x x x(<-50, -100, -200, -300, -400)

SLP x x

HREF ensemble products (7 surface and 7 upper air variables)

Mean Spread Probability

850T x x x(<0C)

850RH x x

850U x x

850V x x

850Wind x x

500T x x

500H x x

250T x x

250U x x

250V x x

250Wind x x

Coming implementations

• ~January 2012: NARRE-TL (North America Rapid Refresh Ensemble – Time Lagged)

• ~April 2012: SREF (Short Range Ensemble Forecast)

NARRE-TL (formerly VSREF)

-Together with the implementation of Rapid Refresh (RR) to replace RUC (Stan Benjamin’s review).

-Background: NCEP and GSD agreement: to implement a “3 WRF-ARW and 3 WRF-NMMB members, hourly-updated N.A. RR Ensemble (6 member NARRE)”

-Before having enough computing resource to operationally run the “6-

member NARRE”, build a Time-lagged NARRE system (NARRE-TL) based on single runs from RR and NAM as a first step to

(1) Fully utilize existing hourly output RR data; (2) Provide probabilistic guidance to aviation weather (similar to the idea of

SPC’s “Probability of Opportunity”); (3) use only very low compute resource (post processing); and (4) Provide a baseline to future real NARRE/HRRRE development and

evaluation.

RR model domain

NARRE-TL (grid#130)

NARRE-TL Alaska, ( grid#242 )

NARRE-TL Configuration 10 weighted time-lagged members collected from: 6 RR members and 4 NAM members (next slide) Two output grids: CONUS (grid#130) Alaska (grid#242)

Forecast hours: 12 hours

Model resolution 12km

Member Weighting = 1 - forecast age (hr)/30:

1.0 for the most current forecast and 0.0 for 30hr-old fcst

(NAM always older than RR gives more weight to RR members)

RR’s first 6 hr forecasts are used.

Example for 06Z cycle’s NARRE-TL members:

06 09 1200 0318 211206

NAM RR

15 18 21 00

6hr TL 12hr FCST

Field Ensemble product

1 Icing Occurrence prob on 8 FL

2 Turbulence (CAT) 3 severity occurrence Prob on 9 FL

3 Ceiling height (cloud base) Mean/spread/prob of 4 ranges

4 Visibility Mean/spread/prob of 4 ranges

5 Low level Wind shear Mean/spread/occurrence prob

6 Jet stream Prob on 3 levels

7 Fog (light/dense) Mean/spread/prob

8 Convection Prob of occ. (Steve W. of GSD)

9 Reflectivity Prob of 4 thresholds

10 Freezing height Mean/spread

11 Precipitation type Prob of rain and snow types

12 Accumulate Precip Prob of 3 and 6hr acc. precip

13 Lightning Prob of occurrence (D. Bright of SPC/AWC)

14 Severe thunderstorm Prob of occurrence (D. Bright of SPC/AWC)

Example products from NARRE-TL (may need a spatial filtering/GSD)

Icing Turbulence

LLWS Visibility

Importance to user community • Subject: VSREF missing• From: [email protected]• Date: Tue, 06 Dec 2011 10:29:59 -0700• To: [email protected]

Jun,

Are you guys having troubles with the VSREF data? We have not received anything since 12/05 at 09Z.

Thanks.

Coming SREF upgrade (Spring 2012) • Model Change 1. Model adjustment (eliminate Eta and RSM two models and add new NEMS-based NMMB model) 2. Model upgrade (two existing WRF cores from v2.2 to version 3.3) 3. Resolution increase (from 32km/35km to 16km/17km)

• IC diversity improvement 1. More control ICs (NDAS for NMMB, GFS for NMM, and RR blended with GFS for ARW) 2. More IC perturbation diversity (regional bleeding, downscaled ETR and blended between the two) 3. Diversity in land surface initial states (NDAS, GFS, and RR)

• Physics diversity improvement 1. More diversity of physics schemes (NAM, GFS, HWRF, NCAR and RR) • New capabilities of post-processing 1. precipitation bias correction (individual members and ensemble mean) 2. clustering and associated mean/prob/spread within a cluster 3. member performance ranking (different weights for different members) 4. downscaling to 5km using RTMA (same as NAEFS, evaluated by DET for SREF)

• New ensemble products 1. max/min, mode, 10-25-50-75-90% forecasts (similar to NAEFS) 2. probs of severe thunderstorm, lightning, dry lightning and fire weather (SPC) 3. addition of hourly ensemble product output from 1-39hr

Evaluation of SLP (opl SREF vs. par SREF, Oct. 23 – Nov. 26, 2011)

Ens mean fcst: RMSE Ens spread: Rank Histogram

Prob fcst: RPSS (12km NAM as ref) Prob fcst: reliability diagram

Evaluation of 250U (opl SREF vs. par SREF, Oct. 23 – Nov. 26, 2011)



Evaluation of 500H (opl SREF vs. par SREF, Oct. 23 – Nov. 26, 2011)

Outlier of opl SREF = 21.1% (to miss truth)Outlier of par SREF = 13.4% (to miss truth)



Evaluation of 2mT (opl SREF vs. par SREF, Oct. 23 – Nov. 26, 2011)



Prob fcst: RPSS (12km NAM as ref)

Prob fcst: reliability diagram

Evaluation of 2mTd (opl SREF vs. par SREF, Oct. 23 – Nov. 26, 2011)



Prob fcst: RPSS (12km NAM as ref)

Prob fcst: reliability diagram

Evaluation of 10m-U (opl SREF vs. par SREF, Oct. 23 – Nov. 26, 2011)




Ensemble mean precipitation forecast: ETS of 24hr-accumulation (against CCPA, Oct. 23 – Nov. 26, 2011)

Ens spread: Rank Histogram of 24hr-accumulated precipitation at F87hr (Oct. 23 – Nov. 26, 2011)

Too much light precipitation at dry-end but less chance to miss heavier precipitation events at high-value end

SREF mean forecasts of 24h-accumulated precipitation at F87 (21z, Nov. 18, 2011)

32km SREF mean (opl) 16km SREF mean (par)

Bias correction can effectively remove over-predicted light precipitation area!

(frequency-matching method similar to that used in GEFS)

16km SREF mean (raw) 16km SREF mean (bias corrected)

24

Precipitation bias correction verification (against CCPA, using 12km NAM as reference for RPSS, Nov. 10-26, 2011)

Ens mean fcst: areal bias (>=0.01”) Ens mean fcst: ETS (>=0.01”)

Prob fcst: RPSS

Clustering: 500H and SLP

Clustering: 2mT and precipitation

32km SREF downscaled to 5km NDFD grid using RTMA

Against RTMA Against observation

How to disseminate extra SREF data and products to forecasters and users?

• Prob of thunderstorm, lightning, dry lightning , fire weather (maybe hold off because SPC needs to update a calibration table), bias corrected ensemble mean precipitation, and cluster means at official NCO web

• Clusters and member ranking information such as weights at ftp site • Max, min, mode, 10-25-50-75-90% forecasts at ftp site (more suitable for point forecasts)• Hourly ensemble products (mean, spread and prob) remain at NCEP CCS since it’s mainly for

AWC who can access CCS (maybe need to convert it to Gempak)• Bias corrected precipitation forecast as a new variable at NOMADS• If downscaled 2.5/5km data will be available (pending at DET), it will be at ftp site for the time

being• Collecting new required variables from field forecasters for planning future AWIPS/AWIPS2

Plans for SREF SREF system: •(1) Improve IC perturbation (3D mask, EMC/DET)•(2) Explore EnKF perturbations from hybrid EnKF/GSI DA system•(3) Improve physics perturbation (stochastic parameterization physics/EMC and stochastic kinetic energy backscatter scheme/DET)Post-processing:•(4) Test BMA method for post processing/DET•(5) Calibrate ensemble spread•(6) Expand bias correction to North America domain (e.g., grid#221)Products:•(7) Produce SREF mean bufr sounding•(8) Build SREF model climate•(9) Explore NAEFS_LAM (combining with Canadian regional ensemble)Data:•(10) Add an ~12km output domain over NA•(11) Add new fields to AWIPS/AWIPS2Verification:•(12) Verify ensemble mean cyclone track (Guangping Lou)

Plans for HRRRE-TL Similarly to NARRE-TL, to develop a new suite of ensemble products called “HRRRE-TL (Hi-Res Rapid Refresh Ensemble – Time Lagged)” based on existing high-resolution single model runs - • 4km NAM-nest• 4km HRW-ARW• 4km HRW-NMM• 4km Matt Pyle run (for SPC)• 3km HRRR (GSD runs)

review of emc regional ensembles: sref, narre-tl, hrrre-tl/href

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