VISTAS Grid Resolution Sensitivity

VISTAS Grid Resolution SensitivityRalph Morris, Bonyoung Koo and Steven Lau

ENVIRON International Corporation

Gail Tonnesen, Zion Wang, Chao-Jung ChienUniversity of California at Riverside

T.W. Tesche and Dennis McNallyAlpine Geophysics

National RPO Modeling Meeting

Denver, Colorado

May 24-25, 2004

Grid Resolution Sensitivity• Three VISTAS Phase I Episodes

– January 2002– July 1999– July 2001

• MM5 PX_ACM(2)• 36 km national RPO grid and 12 km

Southeast US VISTAS Grid• Examine Model Performance in VISTAS

Southeast US Domain

VISTAS Phase I 36/12 km Domains

SO4 IMPROVE 36 km vs. 12 km

January 2002 – SO4 July 1999 – SO4

WSO4 NADP 36 km vs. 12 km

January 2002 – WSO4 July 1999 – WSO4

July 2001 36 km vs. 12 km

July 2001 – SO4 IMPROVE July 2001 – WSO4 NADP

IMPROVE SO4 Fractional Bias and ErrorCMAQ 36 km and 12 km & CB4 and SAPRC99

SO4 Mean Fractional Bias

-40.0

-35.0

-30.0

-25.0

-20.0

-15.0

-10.0

-5.0

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

Jan '0

2 36k

m

Jan '0

2 12k

m

Jul '

99 36

km

Jul '

99 12

km

Jul '

01 36

km

Jul '

01 12

km

Mea

n Fra

ctio

nal

Bia

s

Base CaseSAPRC99

SO4 Mean Fractional Error

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

Jan '0

2 36k

m

Jan '0

2 12k

m

Jul '

99 36

km

Jul '

99 12

km

Jul '

01 36

km

Jul '

01 12

km

Mea

n Fra

ctio

nal

Err

or

Base CaseSAPRC99

IMPROVE NO3 Fractional Bias and ErrorCMAQ 36 km and 12 km & CB4 and SAPRC99

NO3 Mean Fractional Bias

-150.0

-125.0

-100.0

-75.0

-50.0

-25.0

0.0

25.0

50.0

Mea

n Fra

ctio

nal

Bia

s

Base CaseSAPRC99

NO3 Mean Fractional Error

0.0

25.0

50.0

75.0

100.0

125.0

150.0

Jan '0

2 36k

m

Jan '0

2 12k

m

Jul '

99 36

km

Jul '

99 12

km

Jul '

01 36

km

Jul '

01 12

km

Mea

n Fra

ctio

nal

Err

or

Base CaseSAPRC99

IMPROVE OC Fractional Bias and ErrorCMAQ 36 km and 12 km & CB4 and SAPRC99

OC Mean Fractional Bias

-100.0

-90.0

-80.0

-70.0

-60.0

-50.0

-40.0

-30.0

-20.0

-10.0

0.0

10.0

Jan '0

2 36k

m

Jan '0

2 12k

m

Jul '

99 36

km

Jul '

99 12

km

Jul '

01 36

km

Jul '

01 12

km

Mea

n Fra

ctio

nal

Bia

s

Base CaseSAPRC99

OC Mean Fractional Error

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

110.0

Jan '0

2 36k

m

Jan '0

2 12k

m

Jul '

99 36

km

Jul '

99 12

km

Jul '

01 36

km

Jul '

01 12

km

Mea

n Fra

ctio

nal

Err

or

Base CaseSAPRC99

Ozone Performance July 1999 EpisodeCMAQ and CAMx at 36 km and 12 km (CB4)

Mean Normalized Bias in 1- Hr Ozone, (%).

-20.0

-15.0

-10.0

-5.0

0.0

5.0

10.0

15.0

10-J

ul

11-J

ul

12-J

ul

13-J

ul

14-J

ul

15-J

ul

16-J

ul

17-J

ul

18-J

ul

19-J

ul

20-J

ul

21-J

ul

Ave

rage

Mea

n N

orm

aliz

ed B

ias,

%

CMAQ 36 Km CMAQ 12 Km CAMx 36 km CAMx 12 km

CMAQ ozone performance degradation to under-estimation with finer grid

CAMx ozone performance similar at 36 km and 12 km

CAMx 36/12/4 km Performance for MRPO June 18 – August 13, 2001 Episode

CAMx Base E Mean Normalized Bias, (%).

-100.0

-50.0

0.0

50.0

100.0

150.0

200.0

250.0

300.0

Bia

s, %

36 Km Grid 12 Km Grid 4 Km Grid

Mean Normalized Bias

Degradation in most gas-phase species with higher resolution

Aerosol species stay same or improve

CAMx 36/12/4 km Performance for MRPO June 18 – August 13, 2001 Episode

CAMx Base E Mean Normalized Gross Error, (%).

0.0

50.0

100.0

150.0

200.0

250.0

300.0

1-Hr N

O2

1-Hr N

Ox

1-Hr S

O2

1-Hr O

3

8-Hr O

3 O

C ECSO4

NO3NH4

CMSoil

PM2.5

PM10

RCFM

Gro

ss E

rror

, %

36 Km Grid 12 Km Grid 4 Km Grid

Mean Normalized Gross Error

Conclusions: Grid Resolution Sensitivity• Effects of grid resolution on model performance is

mixed• Changes in precipitation patterns and magnitudes can

have large effect locally• Changes in transport patterns also can have big local

effect (e.g., Jim Boylan’s analysis of sulfate clouds)• 12 km grid technically superior for grid modeling than

36 km, but still does not resolve point sources and urban areas very well

• 12 km takes more CPU time than 36 km• VISTAS Phase II annual modeling will use both 36 and

12 km grids