March 4, 2004 

Analysis of MM5 Simulations based on three PBL schemes over the eastern US for 

August 6 to 16, 2002 

Winston Hao, Mike Ku, and Gopal Sistla 

NYSDEC-DAR 

Albany, NY 12233 

Introduction: In a prior report1

 dated December 8, 2003, a comparison was 

performed between meteorological measurements and the simulated MM5 fields for 

August 6 to 16, 2002 based upon 3 approaches to the PBL. In this report, we provide the 

comparison with TDL and CASTNet measurements. 

 

Purpose: The intent of this exercise was to investigate the response of three 

PBL schemes and develop a recommendation for the use of a PBL method for developing 

meteorological fields for the May through September of 2002, in support of air quality 

modeling work. 

Approach: In this study, Prof. Dalin Zhang of University of Maryland, applied 

3 PBL schemes for the August 6 to 16, 2002, a period in which the OTR experienced 

high ozone as well as particulate levels. The three schemes were (a) modified Blackadar

[BL], (b) the Pleim-Xiu scheme with the soil module [PX], and (c) modified Blackadar 

with soil module [SSIB]. The simulated meteorological fields were compared to the 

measurements from TDL (NWS) and CASTNet. 

Model setup: The MM5 model setup is similar to the earlier exercise of

developing meteorological fields for July 1997, with the first level at 10 m. The 

projection for this exercise was that recommended by the RPOs, and has a spatial 

resolution of 12 km (see Figure 1) 

 

Analysis: The basic approach used is to compare domain-wide averaged 

measurements and predictions for surface temperature, wind speed and direction, and 

where available with humidity. While the CASTNet sites are more representative of rural 

areas, the TDL are reflective of urban/suburban settings. There are 47 CASTNet and 

about 600 NWS sites in the TDL data set over the modeling domain. 

TDL data and MM5 simulations: 

Average wind speed and direction (see Figures 2a through 2c) 

1 Hao, W., Ku, M., and Sistla, G. (2002) ‘Preliminary analysis of MM5 simulations for 

the August 6 to 17, 2002 – A status report’, NYSDEC, Albany, NY 12233 

1
Overall, the 3 PBL schemes provide good agreement with the observed average wind 

direction . In terms of wind speed: 

BL: Under prediction of daytime maximum wind speed, but agreement with nighttime 

low windspeed 

P-X: Systematic under prediction during daytime and over prediction in the nighttime 

SSIB: Under prediction during daytime with phase lag, the predicted maximum 

occurring latter than the measured maximum

Temperature (see Figures 3a through 3c) 

BL: Good agreement throughout the episode days 

P-X: Initial over prediction of temperature minimum, and under prediction of daytime 

maximum 

SSIB: Over prediction of daytime maximum 

Humidity (see Figures 4a through 4c)

BL: While the general trend is captured during the episode, there is poor agreement 

between the observed and predicted diurnal patterns, with the observation showing a 

double peak versus one peak based on predictions. 

P-X: The model yields the observed daily double peak, but with underprediction and a 

phase lag. 

CASTNet data and MM5 simulations: 

Average wind speed and direction (see Figures 5a through 5c) 

All 3 PBL approaches provide good agreement with the observed average wind direction. 

In terms of wind speed: 

BL: Wind speed over prediction during the daytime, a feature that differs from the 

TDL results, but good agreement with nighttime minimum 

P-X: Wind speed over prediction, for both day- and nighttime hours.

SSIB: Wind speed over prediction at the start and end of the episode, and exhibiting a 

phase-lag of 1 to 2 hours 

Average Temperature (see Figures 6a through 6c) 

BL: Overall good agreement 

P-X: Systematic under prediction during daytime and over prediction in the nighttime 

with phase lag 

SSIB: Over prediction during the daytime, but good agreement during nighttime

Average Humidity 

2
There were no data to perform this comparison, as mixing ratio cannot be estimated due 

to lack of station pressure. 

Spatial distribution of correlation between TDL data and MM5 simulations 

Wind Speed (see Figures 7a through 7c) 

BL: The correlation levels are generally in the 0.7 or higher range over most portions 

of the domain, with lower values mainly confined to the southeastern and western parts 

of the domain. 

P-X: The correlation levels are slightly lower compared to BL, with more stations 

exhibiting a correlation level of less than 0.6 in the Southeastern portion of the domain. 

SSIB: The correlation levels are similar to P-X, but with increased number of stations 

exhibiting correlation levels less than 0.6 over the domain 

Temperature (see Figures 8a through 8c) 

BL: The correlation levels are generally higher (>0.97) over the northeastern portions 

of the domain, with the remainder of the domain exhibiting correlation levels in the range 

of 0.94 to 0.96 

P-X: Overall the correlation levels are slightly lower than BL 

SSIB: Similar to P-X, with correlation levels in the 0.95 throughout the domain 

Humidity (see Figures 9a through 9c) 

BL: The correlation levels over the northeast are generally higher than the rest of the 

domain, although most portions of the domain report correlation of 0.70 or higher 

P-X: The correlation levels are comparable or slightly better than BLK 

SSIB: The correlation levels are comparatively lower than the other two over the 

northeastern portions of the domain 

 

Discussion and conclusions 

On an overall basis, it appears that the BL scheme exhibits a better correspondence to the 

measured data than the other two schemes. The exception being the poor capture of the 

observed diurnal pattern of humidity in the case of the BL scheme. While the P-X scheme

shows a better correspondence with the observed diurnal pattern for humidity, it fails to

perform well for wind speed and temperature. Further work is needed to improve the 

performance of these methods. An examination of other studies in which the P-X scheme

was applied suggests the predictive performance is similar to this study. 

Other comparisons of model to observed or measured parameters such as cloud cover, 

precipitation, and upper air soundings/profiler network are under examination to provide 

a comprehensive evaluation of the meteorological model. Also, the use of the model 

simulated fields in air quality model and comparison to pollutant fields is also in 

progress. 

3
Figure 2a MM5 Simulation - UMD BLK & TDL - Aug 6 01Z to Aug 17 00Z 2002

Observed/Predicted Windspeed

0

1

2

3

4

5

6

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

ObsWndSpd PrdWndSpd 

Bias Windspeed

-1

-0.5

0

0.5

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

BiasWndSpd

RMSE Windspeed

0

0.5

1

1.5

2

2.5

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

RMSEWndSpd RMSESWndSp RMSEUWndSp

IOA Windspeed

0

0.2

0.4

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1

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IOAWndSpd 

Observed/Predicted Wind Direction

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360

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de

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ObsWndDir PrdWndDir

Bias Wind Direction

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4
Figure 2b MM5 Simulation - UMD PX & TDL Aug 06 01Z to Aug 17 00Z 2002 

5
Figure 2c MM5 Simulation - UMD SSIB & TDL Aug 06 01Z to Aug 17 00Z 2002

Observed/Predicted Windspeed

0

1

2

3

4

5

6

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

ObsWndSpd PrdWndSpd 

Bias Windspeed

-1.5

-1

-0.5

0

0.5

1

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

BiasWndSpd

RMSE Windspeed

0

0.5

1

1.5

2

2.5

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

RMSEWndSpd RMSESWndSp RMSEUWndSp

IOA Windspeed

0

0.2

0.4

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 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

IOAWndSpd 

Observed/Predicted Wind Direction

0

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360

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

de

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ObsWndDir PrdWndDir

Bias Wind Direction

-90

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-30

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90

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

de

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6
Figure 3a MM5 Simulation - UMD BL & TDL Aug 6 01Z to Aug 17 00Z 2002 

7
Figure 3b MM5 Simulation - UMD PX & TDL Aug 06 01Z to Aug 17 00Z 2002

Observed/Predicted Temperature

285

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305

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

ObsTemp PrdTemp 

Bias Temperature

-3

-2

-1

0

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2

3

4

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

BiasTemp 

RMSE Temperature

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2.5

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3.5

4

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

RMSETemp RMSESTemp RMSEUTemp

IOA Temperature

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0.1

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 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

IOATemp 

8
Figure 3c MM5 Simulation - UMD SSIB & TDL Aug 06 01Z to Aug 17 00Z 2002

Observed/Predicted Temperature

285

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305

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

ObsTemp PrdTemp 

Bias Temperature

-2

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-0.5

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0.5

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1.5

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 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

BiasTemp 

RMSE Temperature

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 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

RMSETemp RMSESTemp RMSEUTemp

IOA Temperature

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IOATemp 

9
Figure 4a MM5 Simulation - UMD BL & TDL Aug 6 01Z to Aug 17 00Z 2002

Predicted/Observed Humidity

8

9

10

11

12

13

14

15

16

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

g/k

g

ObsHum PrdHum 

Bias Humidity

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

g/k

g

BiasHum 

RMSE Humidity

0

0.5

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1.5

2

2.5

3

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 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

g/k

g

RMSEHum RMSESHum RMSEUHum 

IOA Humidity

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IOAHum 

10
Figure 4b MM5 Simulation - UMD PX Aug 06 01Z to Aug 17 00Z 

Predicted/Observed Humidity

8

9

10

11

12

13

14

15

16

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

g/

kg

ObsHum PrdHum 

Bias Humidity

-1.5

-1

-0.5

0

0.5

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2

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g/

kg

BiasHum 

RMSE Humidity

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g/

kg

RMSEHum RMSESHum RMSEUHum 

IOA Humidity

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IOAHum 

11
Figure 4c MM5 Simulation - UMD SSIB & TDL Aug 06 01Z to Aug 17 00Z 2002

Predicted/Observed Humidity

8

9

10

11

12

13

14

15

16

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

g/k

g

ObsHum PrdHum 

Bias Humidity

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

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g/k

g

BiasHum 

RMSE Humidity

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g/k

g

RMSEHum RMSESHum RMSEUHum 

IOA Humidity

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IOAHum 

12
Figure 5a MM5 UMD - BL & CASTNet Aug 6 01Z to Aug 17 00Z 2002

Observed/Predicted Windspeed

0

1

2

3

4

5

6

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

ObsWndSpd PrdWndSpd 

Bias Windspeed

-0.5

0

0.5

1

1.5

2

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

BiasWndSpd

RMSE Windspeed

0

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1

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2

2.5

3

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

RMSEWndSpd RMSESWndSp RMSEUWndSp

IOA Windspeed

0

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IOAWndSpd 

Observed/Predicted Wind Direction

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360

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

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ObsWndDir PrdWndDir

Bias Wind Direction

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13
Figure 5b MM5 - UMD PX & CASTNet Aug 06 01Z to Aug 17 00Z 2002 

Observed/Predicted Windspeed

0

1

2

3

4

5

6

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

ObsWndSpd PrdWndSpd 

Bias Windspeed

-0.5

0

0.5

1

1.5

2

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

BiasWndSpd

RMSE Windspeed

0

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1

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2

2.5

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

RMSEWndSpd RMSESWndSp RMSEUWndSp

IOA Windspeed

0

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IOAWndSpd 

Observed/Predicted Wind Direction

0

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360

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

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ObsWndDir PrdWndDir

Bias Wind Direction

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 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

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14
Figure 5c MM5 - UMD SSIB & CASTNet Aug 06 01Z to Aug 17 00Z 2002 

Observed/Predicted Windspeed

0

2

4

6

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

ObsWndSpd PrdWndSpd 

Bias Windspeed

-1.5

-1

-0.5

0

0.5

1

1.5

2

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

BiasWndSpd

RMSE Windspeed

0

0.5

1

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2

2.5

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

m/s

RMSEWndSpd RMSESWndSp RMSEUWndSp

IOA Windspeed

0

0.2

0.4

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1

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

IOAWndSpd 

Observed/Predicted Wind Direction

0

60

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300

360

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

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ObsWndDir PrdWndDir

Bias Wind Direction

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 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

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15
Figure 6a MM5 - UMD BL & CASTNet Aug 6 01Z to Aug 17 00Z 2002

Observed/Predicted Temperature

285

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301

303

305

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

ObsTemp PrdTemp 

Bias Temperature

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

BiasTemp 

RMSE Temperature

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3

3.5

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

RMSETemp RMSESTemp RMSEUTemp

IOA Temperature

0

0.1

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0.5

0.6

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0.9

1

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

IOATemp 

16
Figure 6b MM5 - UMD PX & CASTNet Aug 06 01Z to Aug 17 00Z 2002 

Observed/Predicted Temperature

285

287

289

291

293

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297

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301

303

305

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

ObsTemp PrdTemp 

Bias Temperature

-3

-2

-1

0

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2

3

4

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

BiasTemp 

RMSE Temperature

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3

3.5

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4.5

5

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

RMSETemp RMSESTemp RMSEUTemp

IOA Temperature

0

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IOATemp 

17
Figure 6c MM5 - UMD SSIB & CASTNet Aug 06 01Z to Aug 17 00Z 2002 

Observed/Predicted Temperature

285

287

289

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293

295

297

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301

303

305

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

ObsTemp PrdTemp 

Bias Temperature

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

BiasTemp 

RMSE Temperature

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3.5

4

 8/ 6 8/ 7 8/ 8 8/ 9 8/10 8/11 8/12 8/13 8/14 8/15 8/16

K

RMSETemp RMSESTemp RMSEUTemp

IOA Temperature

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IOATemp 

18
Figure 7a Spatial Correlation – Wind speed – BL & TDL

19
Figure 7b Spatial Correlation – Wind Speed – P-X & TDL

20
Figure 7c Spatial Correlation – Wind Speed SSIB & TDL

21
Figure 8a Spatial Correlation – Temperature – BL & TDL

22
23

Figure 8b Spatial Correlation – Temperature – PX & TDL
Figure 8c Spatial Correlation – Temperature SSIB & TDL

24
Figure 9a Spatial Correlation - Humidity BL & TDL 

25
Figure 9b Spatial Correlation – Humidity PX & TDL

26
Figure 9c Spatial Correlation – Humidity SSIB & TDL

27