Download - Regional Modeling Update and Issues

Regional ModelingUpdate and Issues

May 6, 2003

Air Resources Board

California Environmental Protection Agency

Luis F. Woodhouse, Ph.D.

RegionalModeling

IntegratedResults

Risk Assessment

Mapping andVisualization

MicroscaleModeling

Emissions andMeteorology

Outline

• Review of last meeting

• Regional modeling update

• Model evaluation

• Comparison with previous studies

• Integrating microscale and regional modeling

• Future analysis

• Future statewide modeling considerations

3

Review of Last Meeting (September 12, 2002)

• Previous studies– UAM and CAMx with Carbon Bond IV

– Select toxics

– Small domain

• Present study– CALGRID and CMAQ with SAPRC99

– Over 30 toxics

– Large domain• Note: CAMx not used since it’s implementation mechanism

software is not publicly available

4

Toxics– 1,3-butadiene– Formaldehyde– Acetaldehyde– Acrolein – Benzene– Carbon tetrachloride– Chloroform– Dichloromethane– 1,2-Dichloroethane– o-Dichlorobenzene– p-Dichlorobenzene– Ethylene oxide– Styrene

– Toluene– Vinyl Chloride– Xylenes– Hexavalent Chromium

– Diesel PM10

– PM10 Arsenic

– PM10 Beryllium

– PM10 Cadmium

– PM10 Lead

– PM10 Manganese

– PM10 Mercury

– PM10 Nickel

– PM10 Zinc

5

Regional Modeling Domain

San Diego

Riverside

Los AngelesSan BernardinoVentura

Orange

Mexico

6

Regional Modeling Domain

93,264 km2

87 x 67 grids(4 km x 4 km)

Model Inputs • Emissions

– SCOS97 adjusted to 1998– seasonal inventories (weekday/weekend)– latest profiles, surrogates, and EMFAC2000

(with DTIM4)

• Meteorology– CALMET: diagnostic model using data from over

200 sites– MM5: prognostic model

• Boundary conditions– same for each month, based on SCOS97

7

Regional Modeling Update

• CALGRID– January 1 to December 31, 1998

• CMAQ– January, April, August and November 1998

8

Model Performance

• Verify model’s ability to reproduce measured concentrations– Ozone: Performance standards are well

established

– Toxics: No established performance standards

9

Model PerformanceConclusions

• Iterative process is needed to improve ozone performance

• In general, model predicted annual average toxics concentrations are comparable with observations for most species

• Results comparable with previous studies

10

Ozone Model Evaluation• Compared daily ratios of model-predicted to

measured maximum ozone concentrations– CALGRID closer to observations– CMAQ over predicts

11

0

0.5

1

1.5

2

2.5

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29

Day of Month (August 1998)

Ratio

CMAQ CALGRID

Ozone Model Evaluation (cont.)• Calculated daily average gross errors:

– Measure model’s overall ability to reproduce observed hourly ozone at each site above a specified threshold concentration

– Iterative process

12

0

0.2

0.4

0.6

0.8

1

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29

Day of Month (August 1998)CMAQ CALGRID

Toxic VOCs Model Evaluation

• Annual average concentrations– In general, model predictions are

comparable with the measured annual concentrations for most toxics VOC species

– Some species are significantly under predicted by both models: carbon tetrachloride, chloroform, ethylene chloride, styrene

13

1998 Annual Average Concentration in Los Angeles

0

1

2

3

4

5

6

7

AC

ET

BU

TD

C6H

6

C7H

8

CC

HO

CC

L4

CH

LO

DIC

M

HC

HO

MEK

PDC

B

PER

C

STY

R

TED

C

VC

HL

ppb

CALGRID CMAQ Observed

Annual Averages of Toxic VOCs

14

1998 Annual Average Concentrations in Anaheim

0

1

2

34

5

6

7

AC

ET

BU

TD

C6H

6

C7H

8

CC

HO

CC

L4

CH

LO

DIC

M

HC

HO

MEK

PD

CB

PER

C

STY

R

TED

C

VC

HL

ppb


1998 Annual Average Concentration in Chula Vista

00.5

11.5

22.5

33.5

AC

ET

BU

TD

C6H

6

C7H

8

CC

HO

CC

L4

CH

LO

DIC

M

HC

HO

MEK

PD

CB

PER

C

STY

R

TED

C

VC

HL

ppb


15

Annual Averages of Toxic VOCs

Annual Averages ofInert Toxics

• Diesel PM10

– Model predictions are comparable to observed elemental carbon results

• Hexavalent Chromium– Model predictions are below detection limit

• PM10 components

– Performance depends on species

16

Annual Average of Inert Toxics

1998 Annual Concentrations at Los Angeles

0

50

100

150

200

ARSE CADM CRVI DIES LEAD MERC NICK ZINC

ng/m

3


*

* DIES in ug/m3 compared to elemental carbon 17

1998 Annual PM10 Concentrations at Anaheim

0

50

100

150


ng/m

3


1998 Annual Concentration at Chula Vista

0

20

40

60


ng/m

3


18

*

*

*

* DIES in ug/m3 compared to elemental carbon

Annual Average of Inert Toxics

19μg/m3

CALGRID (1998)

ppb

Diesel PM10 Benzene

Comparison withPrevious Studies

• MATES II– April 1998 to March 1999 field study– Models

• UAM and recently CAMx• Carbon Bond IV reaction mechanism

• Our results are comparable

20

0

0.5

1

1.5

2

2.5

ppb

CALGRID CMAQ MATESII (UAM) Observed

Comparison with MATES IIBenzene

21

Comparison with MATES II Diesel PM10 vs. Elemental Carbon

02468

101214

ug/m

3


22

Comparison with MATES II Formaldehyde

01

234

56

ANAH

BLO

G

BUR

K

CEL

A

CH

VA

CO

MP

FON

T

HPR

K

LGBH

PIC

O

RIV

R

SIM

I

UPL

A

WIL

M

ppb


23

Integrating Microscale and Regional Modeling Results

• Microscale modeling estimates near source impacts (meters)

• Regional modeling estimates impacts from sources in a large area (km)

• Issue– double-counting

24

25

Barrio Logan Modeling Results

ISCST3 CALINE CALGRID BARRIO CHULA EL -----------BARRIO LOGAN-------------- LOGAN VISTA CAJON

DIESEL PM10

26

ISCST3 CALINE CALGRID BARRIO CHULA EL -----------BARRIO LOGAN-------------- LOGAN VISTA CAJON

BENZENE

Barrio Logan Modeling Results (cont.)

27

ISCST3 CALINE CALGRID BARRIO CHULA EL ---------BARRIO LOGAN-------------- LOGAN VISTA CAJON

HEXAVALENT CHROMIUM

Barrio Logan Modeling Results (cont.)

NA

Sensitivity Simulations Double Counting*

• In Barrio Logan, local emissions contribute less than 1% of the annual average concentration of most toxic species.

• In Wilmington, local emissions contribute 15%-90% of the annual average concentrations– Benzene (47%)– Diesel exhaust (40%)– 1,3-butadiene (16%)

28* simulations for all 1998 were done in each case with CALGRID

Sensitivity SimulationsBarrio Logan

• Changing boundary conditions has very small impact on annual average toxic concentrations

• Choosing different averaging periods – 12-month average toxic concentrations can be

significantly different from 4-month average concentrations

– 4-month average cumulative risk is about 10% higher than the 12-month average cumulative risk

29

Future Analysis• Improve estimates of background toxic

concentrations – Omit all toxics emissions in a cell– Omit toxic emissions from selected categories in a cell– Evaluate procedures for estimating contributions of

secondary species

• Evaluate deposition effect

• Run CALGRID using MM5 winds

• Conduct spatial analysis

30

Future Statewide Modeling Considerations

• Air quality model selection– CALGRID, CMAQ, CAMx, other – Atmospheric reaction mechanism– Run time (e.g., CALGRID with SAPRC99

and 4 km x 4 km grids, at least 6 months)

• Period simulated– Every day in a year or selected episodes

31

Future Statewide Modeling Considerations (cont.)

• Input preparation– Emissions – Meteorology (CALMET, MM5)

• Other considerations– Baseline year– Multiple year simulation– Storage requirements

32