1.9 UPDATE ON WRF-ARW END-TO-END MULTI-SCALE FDDA SYSTEM

UPDATE ON WRF-ARW END-TO-END MULTI-SCALE FDDA SYSTEM

Aijun Deng, David Stauffer, Brian GaudetPenn State University

Jimy Dudhia, Joshua Hacker, Cindy Bruyere, Wanli Wu, Francois Vandenberghe, Yubao Liu and Al Bourgeois NCAR

10th Annual WRF Users’ Workshop

June 23-26, 2009, Boulder, CO

2

Objectives

• Current status of the nudging FDDA capabilities in WRF-ARW, and status of the end-to-end FDDA system.

• Test results of WRF nudging FDDA in a multiscale FDDA framework, using a model configuration with typical vertical resolution.

• Test results of the end-to-end FDDA system, using a model configuration with very high vertical resolution.

• Future Plans

3

Two Approaches to Nudging (Newtonian Relaxation)

• Nudge to gridded analyses of observations• Nudge to individual observations(multi-scale FDDA, Stauffer and Seaman 1990, 1994)

( ) ...obGt

t t

0 0

( ) computed in grid space analysis nudging( ) computed in obs space obs nudging

( ) ( ) ( )t

1 folding-time

ob

ob

Gtob o ob obdt G dt t e

eG

O(1 )h

4

wxy

w

wt

Observation Nudging Weighting Functions

5

• CAPTEX-83 Case

48-h model simulation, 36-km/12-km/4-km domains, 32 vertical layers with the first half layer at ~30 m

Starting: 1200 UTC, 18 Sept. 1983Ending: 1200 UTC, 20 Sept. 1983(IC/LBC/FDDA inputs based on MM5 RAWINS)Physics: MYJ PBL, KF CPS on 36- and 12-km grids,

Dudhia SW and RRTM LW, etc

6

MM5/WRF Domains: 108, 36, 12 and 4 km

7

Experimental Design for Multi-scale FDDA

CAPTEX-83 (36/12/4-km grids)

YESNOYESYESYESYESMFDDA

NONONOYESNOYESGFDDA

YESNOYESNOYESNOOFDDA

NONONONONONONOFDDA

OBS Nudging

3D Analysis Nudging

OBS Nudging

3D Analysis Nudging

OBS Nudging

3D Analysis Nudging

4-km12-km36-kmExp. name

8

222N/AN/AN/ATWINDO (hr)

2060180N/AN/AN/Adt (sec)

1042N/AN/AN/AIONF

100100150N/AN/AN/ARINXY (km)

Nudging above PBL

Nudging above PBL

Nudging above PBLN/ANudging

above PBLNudging above PBLMass field

Nudging all layers

Nudging all layers

Nudging all layersN/ANudging all

layersNudging all layersWind field

4*10-44*10-44*10-4N/A1*10-43*10-4G (1/sec)

4-km12-km36-km4-km12-km36-km

OBS Nudging3D Analysis Nudging

FDDA Experimental Design and ParametersCAPTEX-83 (36/12/4-km grids)

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CAPTEX-83: MAE of WRF-Simulated Fields Averaged Over 48-h Time Period and All Model Layers

MAE of Vector Wind Difference

0

0.5

1

1.5

2

2.5

3

3.5

4

36-km 12-km 4-km

m/s

NOFDDAOFDDAGFDDAMFDDA

MAE of Wind Direction

0

5

10

15

20

25

36-km 12-km 4-km

Degr

ee


MAE of Temperature

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

36-km 12-km 4-km

K


MAE of Water Vapor Mixing Ratio

0

0.2

0.4

0.6

0.8

1

1.2

36-km 12-km 4-km

g/kg


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CAPTEX-83: MAE of WRF-Simulated Surface Layer Fields Averaged Over 48-h Time Period

MAE of Surface-layer Vector Wind Difference

0

0.5

1

1.5

2

2.5

3

3.5

4

36-km 12-km 4-km

m/s


MAE of Surface-layer Wind Direction

0

5

10

15

20

25

30

35

40

36-km 12-km 4-km

Degr

ee


MAE of Surface-layer Temperature

0

0.5

1

1.5

2

2.5

3

36-km 12-km 4-km

K


MAE of Surface-layer Water Vapor Mixing Ratio

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

36-km 12-km 4-km

g/k


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• Alaska-08 Case

72-h model run, 12-km/4-km domains, 45 model layers very high vertical resolution, with half-layer heights of 2 m, 6m, 10m, etc.

Starting: 0000 UTC 23 Jan 2008Ending: 0000 UTC 26 Jan 2008(IC/LBC/FDDA inputs based on WRF OBSGRID)

Physics: MYJ PBL, KF CPS on 12- km grid,Dudhia SW and RRTM LW, Noah LSM, etc

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Alaska-08 Domains: 12 and 4 km

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YESNOYESYESMFDDA/MFDDAS

YESNONOYESGFDDA/GFDDAS

NONOYESNOOFDDA

NONONONONOFDDA

OBS Nudging3D/Sfc Analysis NudgingOBS Nudging3D/Sfc Analysis

NudgingExp. Name

4-km12-km

Experimental Design for Multi-scale FDDAAlaska-08 Jan 2008 (12/4-km grids)

15

22N/AN/ATWINDO (hr)

824N/AN/Adt (sec)

124N/AN/AIONF

100100N/AN/ARINXY (km)

Nudging all layersNudging all layersN/ANudging all layersMass field

Nudging all layersNudging all layersN/ANudging all layersWind field

4*10-44*10-4N/A3*10-4G (1/sec)

4-km12-km4-km12-km

OBS Nudging3D/Sfc Analysis Nudging

FDDA Experimental Design and ParametersAlaska-08 Jan 2008 (12/4-km grids)

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Alaska-08: RMSE of WRF-Simulated Fields Averaged Over Three 12 UTC (3 LST) Times and All Model Layers below 750 hPa

RMSE of U-component

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

12-km 4-km

m/s

NOFDDAOFDDAGFDDAGFDDASMFDDAMFDDAS

RMSE of V-component

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

12-km 4-km

m/s


RMSE of Temperature

0

0.5

1

1.5

2

2.5

3

3.5

4

12-km 4-km

K


RMSE of Relative Humidity

0

5

10

15

20

25

30

12-km 4-km

%


17

Alaska-08: RMSE of WRF-Simulated Surface Fields Averaged Over Three 12 UTC (3 LST) Times

RMSE of Surface U-component

0

0.5

1

1.5

2

2.5

3

3.5

4

12-km 4-km

m/s


RMSE of Surface V-component

0

0.5

1

1.5

2

2.5

3

3.5

12-km 4-km

m/s


RMSE of Surface Temperature

0

1

2

3

4

5

6

12-km 4-km

K


RMSE of Surface Relative Humidity

0

5

10

15

20

25

12-km 4-km

%


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PBL Depth at 60 h, 3 LST

PBL Depth at Fairbanks

Model Sounding at Fairbanks

WRF-Simulated PBL Depth (m)

*

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A Simple Weighting Function Used for the Vertical Spreading of Surface Innovation

35 m

23 m

12.5 m

8 m

4 m

0.0 1.0

velo

city

wei

ghtin

g fu

nctio

n 35 m

23 m

12.5 m

8 m

4 m

0.0 1.0

velo

city

wei

ghtin

g fu

nctio

n 35 m

23 m

12.5 m

8 m

4 m

0.0 1.0

tem

pera

ture

wei

ghtin

g fu

nctio

n

35 m

23 m

12.5 m

8 m

4 m

0.0 1.0

tem

pera

ture

wei

ghtin

g fu

nctio

n

Wind Fields Mass Fields

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Alaska-08: RMSE of WRF-Simulated Fields Averaged Over All Three 12 UTC Times and All Model Layers below 750 hPa

RMSE of U-component

00.5

11.5

22.5

33.5

44.5

5

12-km 4-km

m/s

NOFDDAMFDDAOMFDDAS

RMSE of Temperature

0

0.5

1

1.5

2

2.5

3

3.5

12-km 4-km

K

NOFDDAMFDDAOMFDDAS

RMSE of Relative Humidity

0

5

10

15

20

25

30

12-km 4-km

%

NOFDDAMFDDAOMFDDAS

RMSE of V-component

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

12-km 4-km

m/s

NOFDDAMFDDAOMFDDAS

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Alaska-08: RMSE of WRF-Simulated Surface Fields Averaged All Three 12 UTC Times


0

0.5

1

1.5

2

2.5

3

3.5

12-km 4-km

m/s

NOFDDAMFDDAOMFDDAS


0

0.5

1

1.5

2

2.5

3

3.5

12-km 4-km

m/s

NOFDDAMFDDAOMFDDAS


0

1

2

3

4

5

6

12-km 4-km

K

NOFDDAMFDDAOMFDDAS


0

5

10

15

20

25

12-km 4-km

%

NOFDDAMFDDAOMFDDAS

22

Alaska-08: RMSE of WRF-Simulated Surface Fields Averaged Over All 3-h Times


0

0.5

1

1.5

2

2.5

3

3.5

4

12-km 4-km

m/s

NOFDDAMFDDAOMFDDAS


0

0.5

1

1.5

2

2.5

3

3.5

12-km 4-km

m/s

NOFDDAMFDDAOMFDDAS


0

1

2

3

4

5

6

12-km 4-km

K

NOFDDAMFDDAOMFDDAS


15.5

16

16.5

17

17.5

18

18.5

19

19.5

20

12-km 4-km

%

NOFDDAMFDDAOMFDDAS

23

Terrain on the Alaska-08 4-km grid

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Surface Observations

2-m (k=1) Model Temperature and 10-m (k=3) Wind

(MFDDAS)

4-km Grid, 0600 UTC 25 Jan 2008

2-m (k=1) Model Temperature and 10-m (k=3) Wind

(NOFDDA)

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Summary and Conclusions

• PSU leads the DTRA-funded nudging FDDA implementation in WRF, and has recently released its surface analysis nudging in WRFV3.1.

• PSU has been working with NCAR to improve observation nudging and to build an end-to-end FDDA system.

• The end-to-end FDDA system involves observation preprocessing, objective analysis with OBSGRID (or VAR), and observation QC.

26

Summary and Conclusions –CAPTEX-83 Multiscale FDDA

• Multiscale FDDA results for the 48-h CAPTEX dynamic analysis case, both 3D analysis-nudging only and obs-nudging only significantly reduce model error.

• Analysis nudging shows closer fit to obs than obs nudging on the coarser 36-km grid, and obs nudging better fits the obs than analysis nudging on the 12-km grid, as expected due to stronger obs nudging strength.

• Multiscale FDDA produces the best fit to the obs over all three domains.

• On the 4-km grid, multiscale FDDA (combined both 3D analysis nudging and obs nudging on coarser domains, and only obs nudging on finer domains) produces comparable or slightly better fit to the obs compared to using obs-nudging only.

27

Summary and Conclusions –Alaska End-to-End FDDA System

• First multiscale WRF FDDA application using the end-to-end FDDA system.

• Multiscale FDDA (combined 3D analysis and obsnudging on 12-km domain, obs nudging on 4-km domain) is the best overall in fitting the observations.

• Degradation while using surface-data nudging is caused by spreading surface innovations throughout the high PBL depths predicted by WRF MYJ PBL scheme.

• Using simplified vertical weights near the surface for surface-data nudging caused large improvement in all variables compared to NOFDDA control, and also slight improvement with the addition of surface analysis nudging when verified at all 3-hourly times throughout the 72-h period.

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FUTURE WORK

• Improving the nudging strategy so that the vertical spreading of the surface obs is not solely dependent on the PBL depth. Other factors such as PBL Regime should be used in addition to the PBL depth.

• Implement improved strategies for applications with very high vertical resolution.

• Expand the flexibility of the WRF observation nudging to include options often used at Penn State for MM5 obs nudging (e.g. height-level based observations, additional space and time weighting factors for surface observations, additional options for vertical spreading of surface data and anisotropic horizontal weighting functions in the vicinity of terrain, improved QC at finer vertical resolution for FDDA observation data sets, etc).

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FUTURE WORK

• Transition hybrid nudging – EnKF from Lorenz and shallow water model (Lei and Stauffer 2008,2009) to WRF.

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ACKNOWLEDGEMENTS

• WRF nudging FDDA implementation is supported by the Defense Threat Reduction Agency under contract no. HDTRA-1-07-C-0076 through Penn State under the supervision of Dr. John Hannan.

• The Alaska WRF modeling study is also supported by US EPA under contract no. EP08D000663 through Penn State under the supervision of Drs. Ken Schere and Jon Pleim.

• We also acknowledge Jeff Zielonka and Brian Reen of Penn State for their help in WRF verification for the Alaska case study

1.9 UPDATE ON WRF-ARW END-TO-END MULTI-SCALE FDDA SYSTEM

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