Regional Modeling Update

September 12, 2002

Air Resources BoardCalifornia Environmental Protection Agency

Ajith Kaduwela, Ph.DLuis F. Woodhouse, Ph.D.

Collaborators• Emissions

– Paul Allen, P.E.– Emissions Inventory Branch

• Meteorology– Shuming Du, Ph.D.– Kemal Gurer, Ph.D.– Daniel Chau, Ph.D

• Air Quality– Luis Woodhouse, Ph.D.– Jinyou Liang, Ph.D.

• Chemistry– Bruce Jackson, M.S.

Outline• Summary of Draft Modeling Protocol

• Photochemical Models Used

• Model Input Preparation

• Meteorological Models Used

• Modeling Results/Performance Evaluation

• MATES-II, CRC/DOE/NERL Study

• Future Work

Summary of Modeling Protocol

• Modeling Approach:– Apply air quality models to assess health

impacts from direct inhalation at both micro and regional scale.

– Micro-scale modeling for near source impacts– Regional scale to simulate transport of

pollutants from all emission sources in Southern California

Modeling Protocol (cont.)

• Simulate air quality from January 1 to December 31, 1998

• Modeling Domain– 87 x 67 cells– 4 x 4 km2 grid size

Regional Modeling Domain

San Diego

Riverside

Los AngelesSan BernardinoVentura

Orange

Mexico

Modeling Protocol (cont.)

• Emissions– Seasonal weekend and weekday inventories

instead of monthly– Total of 8 emission inventories

• Chemical Mechanism– SAPRC-99– Modified to include additional toxics

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

– Trichloroethylene– Vinyl Chloride– Xylenes– Diesel PM10– Arsenic– Beryllium– Cadmium– Hexavalent Chromium– Iron– Lead– Manganese– Mercury– Nickel– Zinc

Modeling Protocol (cont.)

• Two grid-base photochemical models

– Run Models-3/CMAQ for selected episodes

– Run one air quality model for entire 1998• using CALGRID instead of UAM-FCM

Air Quality Model Change

• Why not UAM-FCM?– Based on older version of UAM (UAM-IV)– No longer supported– Chemical solver difficulties

• Why CALGRID?– Better formulation than UAM-IV– Better documentation– Flexible chemical mechanism

CALGRID

• Grid-based photochemical model developed in 1989 for ARB and last updated in 2000 (Version 1.6b)

• Choice of chemical mechanisms (CB4 or SAPRC)

• ARB’s implementation of a flexible chemical mechanism interface

Community Multiscale Air Quality Modeling System

Models-3/CMAQ

• Photochemical air quality model first released in 1999 with EPA funding.

• State-of-the-Science but limited use to date

• Continually under development

• Aqueous-phase chemistry, aerosol dynamics and modal size distributions, aerosol deposition, plume chemistry, and process analysis

CMAQ vs. CALGRID

• CMAQ– MM5– 17 vertical layers– Domain top: 14.6 km– SAPRC-99 with toxics– QSSA or SMVGEARSMVGEAR– dry deposition for some

toxic VOCs– first order decay for

deposition of PM– 7 days of CPU/month– 1 GB/day

• CALGRID– CALMET– 10 vertical layers– Domain top: 3 km– SAPRC-99 with toxics– QSSA or HybridHybrid– dry deposition for all

toxic VOCs– particulate deposition for

PM– 3 days of CPU/month– 0.5 GB/day

Model Input Preparation

• Initial and Boundary Conditions

• Emissions

• Meteorology

Initial and Boundary Conditions

• Initial and Boundary conditions same for each month– Boundary conditions same as for SCOS-97

• EPA Clean over ocean (40 ppb O3, 0.001 ppb NOx, and 20 ppbC VOC)

• South Coast clean over land (40 ppb O3, 2 ppb NOx, 60 ppbC VOC)

• MATES-II• 40 ppb O3, 1.5 ppb NOx, 30 ppbC VOC

Emissions

• Based on inventories developed for SCOS-97, adjusted to 1998

• Weekend and weekday inventories by season

• Using latest profiles, and surrogates to spatially allocate emissions

• Use latest version of EMFAC2000 for motor vehicle inventory with DTIM4

0

200

400

600

800

1,000

1,200

1,400

1,600

NOx VOC Toxics PM Biogenics

Winter WD Winter WE Summer WD Summer WE

Weekend and Weekday Area Source EmissionsWinter and Summer 1998

tons/day

0

10

20

30

40

50

60

NOx VOC Toxics PM toxics

Winter WD Winter WESummer WD Summer WE

Weekend and Weekday Elevated Emissions

tons/day

Levels

(kg/hr):

1 (B)

10 (G)

50 (Y)

80 (O)

100 (R)

Levels

(kg/hr):

1 (B)

10 (G)

50 (Y)

80 (O)

100 (R)

0 hr 6 hr

12 hr 16 hr

Summer Weekday

NO

Levels

(kg/hr);

1 (B)

2 (G)

3 (Y)

4 (O)

5 (R)

Levels

(kg/hr);

1 (B)

2 (G)

3 (Y)

4 (O)

5 (R)

0 hr 6 hr

12 hr 16 hr

Summer Weekday

BENZENE

Levels (kg/hr):

1 (B)

3 (G)

4 (Y)

5 (O)

6 (R)

Levels (kg/hr):

1 (B)

3 (G)

4 (Y)

5 (O)

6 (R)

0 hr 6 hr

12 hr 16 hr

Summer Weekday

DIESEL PM10

Meteorology

• Models require hourly meteorological data for each grid in domain

• Models needed to create gridded meteorological fields– Prognostic: predicts from first principles, mass

and energy transfer equations (MM5)– Diagnostic: uses observational data

(CALMET)

NCAR/Penn State Mesoscale Model (MM5)

• Advanced state-of-the-science prognostic regional model– solves conservation equations to predict winds

and temperatures– requires initial conditions, and boundary

conditions for each hour simulated

• Applied with one coarse and one nested domain

MM5 (cont.)

• Analysis nudging used but no Data assimilation (FDDA)

• 27 vertical layers (matched to 17 for air quality simulations)

• MM5 exercised for entire 1998

CALMET

• Diagnostic generation of meteorological fields with objective analysis

• Parameterized treatments of slope flows, kinematic terrain effects, terrain blocking effects, and a micro meteorological model for overland and overwater boundary layers

CALMET (cont.)

• Model driven by observations– 10 National Weather Service surface sites– ~100 California Irrigation Management System

(CIMIS) surface stations– One upper air (NWS) site and two buoys– ~60 surface ARB/District monitoring sites (for

January and August only)

Model Output Example:August 5, 1998 @ 12:00hrs

MM5 CALMET

Model Output Example:January 20, 1998 @ 12:00hrs

MM5 CALMET

Model Performance Evaluation

• Process of establishing that an air quality model is adequately reproducing the chemical and physical processes that generate and transport pollutants (“right answer for the right reason”)

• Spatial and temporal evaluations needed

Model Performance Evaluation

• Procedures well established for episodic hourly concentrations of O3

– peak estimation accuracy, mean bias, variance, gross error, scatter plots, time series plots, and isopleths

– diagnostic and sensitivity simulations

• No procedure established for 24-hr or annual concentrations

• Approach:– Hourly evaluation of selected episodes for O3,

NOx, and CO using ARB guidance

– Several days to monthly evaluation of O3, NOx, CO, toxic VOCs (24-hr) and PM components

– Annual performance evaluation

Model Performance Evaluation (cont.)

Data For Model Evaluation

• 1-hr average concentrations for all 1998• O3, NO, CO, NO2

• ARB and District monitoring sites

• 24-hr Average concentrations for PM10 components

• 24-hr measurements for selected VOCs

Completed Simulations• CMAQ/Models-3

– August 1- 7, 1998

– January 1-31, 1998

– Performance evaluation

• CALGRID– August 1-7, 1998

– January 1-31, 1998

– Performance Performance evaluationevaluation

Domain Peak 1-hr Ozone (ppb)August 2-7, 1998

Day Observed CALGRID CMAQ

Aug 2 188 173 285Aug 3 165 163 294Aug 4 170 205 279Aug 5 202 147 234Aug 6 197 178 220Aug 7 206 120 277

Peak O3

Aug 2 @ 14 hrs

CALGRID

CALGRID

CMAQ: AUG 2 @ 17 hrs CMAQ: AUG 3 at 16 hrs

Aug 3 @ 13 hrs

24-hr Model PerformanceAugust 1-7, 1998

• Calculated 24-hr monthly average for O3, CO, and NOx (from hourly values) and compare with predictions

• Insufficient data to fully assess 24-hr model performance for toxics

02468

1012141618202224

BU

TD

C6H

6

C7H

8

CC

HO

HC

HO

DIC

M

MT

BE

TC

E

AR

SE

IRO

N

LE

AD

MA

NG

NIC

K

ZIN

C EC

PM

10

CO

NO

NO

2

O3

CMAQ CALGRID

Ratio of Predicted-to-Observed 24-hr averages for Toxics on August 1-7, 1998

Observed Maximum 1-hr OzoneJanuary 1-31, 1998

Concentration(ppb)

Date

Observed 79 January 1

CMAQ 154 January 18

CALGRID 143 January 26

CMAQ/Models-3 January 18 @ 14 hrs

January 1998 Predicted Ozone Distribution During Peak

CALGRIDJanuary 26, 1998 at 16 hrs

24-hr Model PerformanceJanuary

• Calculated 24-hr monthly average for O3, CO, and NOx (from hourly values) and compare with predictions

• Insufficient data to fully assess 24-hr model performance for toxics

Ratio of Predicted-to-Observed 24-hr Averages for Toxics on January, 1998

0

2

4

6

8

10

12

14

16

BUT

D

C6H

6

C7H

8C

CH

O

DIC

M

HC

HO

MT

BE

OX

YL

PER

C

TCE

IRO

N

LEA

DM

AN

G

NIC

K

ZIN

C

PM10 CO NO

NO

2

O3

CMAQ CALGRID

SUMMARY

• Prepared inputs for all 1998 for CALGRID and CMAQ/Models-3

• Simulated an extended period (January) and part of August with CALGRID and CMAQ/Models-3

• 24-hr average concentrations: On average both models show similar 24-hr performance (both January and August 1-7)

MATES IIMultiple Air Toxics Exposure Study II

• South Coast Air Quality Management District

• Monitored ~30 pollutants from April 1, 1998 to March 31, 1999 at 10 sites

• Air quality modeling for entire MATES II period– UAM with CB-IV and UAM-tox with updated CB-IV

• CALMET for meteorology

• Domain– 105 x 60 cell (2x2 km2), 5 layers ; region top of 2 km

CRC & DOE/NREL Study

– Final report dated June 30, 2000– CAMx/RTRAC to treat reactive inert species– Simulated MATES II using CB-IV

• MATES II Mobile source emissions EMFAC7G

• MATES II Mobile source emissions update to reflect EMFAC2000

• Meteorological fields from CALMET

• 10 MATES-II sites for model performance

• August 3-7, 1997 (MM5, CB-IV and SAPRC-99)

Future Work

• January, 2003:– CALGRID for entire year– Models-3/CMAQ for selected periods – Model performance evaluation– Annual averages and potential risks– Contour plots of risk by species and total risk

• February, 2003: – Draft report