Modeling AerosolFormation and Transport in the

Pacific Northwest with the Community Multi-scale Air Quality

(CMAQ) Modeling System

Susan M. O'Neill

Fire and Environmental Applications (FERA) Team

USDA Forest Service

Seattle, WA

The NorthWest Regional Modeling Center (NWRMC)

• Collaborators: EPA Region X, WSU, States of Washington, Oregon, and Idaho, and Canada

• Study Period: July 3-15,1996

• 12 km Domain: Washington, Oregon, Idaho, SW Canada

• Two Emission Inventories

• NET96, BEIS2

• NWRMC, GLOBEIS

• Chemical Mechanism: RADM2_CI4_AE2_AQ

12 km Domain Terrain Elevation

Chemical Observation Stations

Emission Inventory Summary

Metric tons per day

Anthropogenic Emissions

Biogenic

Emissions

Total

Emissions

NET96 NWRMC NET96

(BEIS2)

NWRMC

(GLOBEIS)

NET96 NWRMC

Isoprene 11235 6569 11235 6569

OLT 77 134 0 8787 77 8921

Terpenes 4409 17883 4409 17883

Total VOC 2713 3301 20509 57506 23222 60807

NH3 1019 130 1019 130

NOx 2306 3332 569 569 2874 3900

Biogenic VOC emissions are 2.8 times higher in the NWRMC EIMBO (lumped into OLT) accounts for 14% of the VOC’s in the NWRMCTerpene emissions are 4 times higher in the NWRMC

Anthropogenic NH3 emissions are 7.8 times higher in the NET96 EI

Results - Aerosol Concentrations

• Compare 2 CMAQ solutions with 12 IMPROVE Station Measurements for:– Total PM2.5– Inorganic PM2.5 - SO4, NO3, (NH4)

• Influence of molar ratio of[NH3 + NH4]/[SO4]

– Organic PM2.5– Visibility

• Aerosol Concentrations at the Columbia River Gorge (CRG).

9849Error (%)

93-15Bias (%)

0.500.54Index

0.430.32R^2

NWRMCNET96Total PM2.5

NWRMC: PM2.5 < 20µg/m3 for much of period, then up to 35 µg/m3 in CRG, Olympics and Central Idaho.

NET96: Similar in trend to NWRMC but lower concentrations. Similar hot spots in Portland (45 µg/m3)/CRG and Olympics but not in Central Idaho. (July 14, 1996, 7am)

(July 14, 1996, 7am)

NWRMC

NET96

Inorganics impact the Urban corridor west of the Cascades with some advection through the CRG. Urban effect much more pronounced in the NET96, especially at Portland with concentrations up to 15 ug/m^3 Little diurnal variation of inorganics on a domain average. (NWRMC = 1.3 ug/m^3, NET96 = 0.15 ug/m^3)

7610410565Error (%)

-72-586-47Bias (%)

0.610.570.390.49Index

0.560.560.040.18R^2

NWRMCNET96NWRMCNET96

NO3SO2Inorganic

Aerosols

(July 14, 1996, 7am)

(July 14, 1996, 7am)

NWRMC

NET96

Ratio:[NH4+NH3]/SO4

July 14, 1996, 7am

NWRMC: Ratio varied about 1SO4 Formation DominatesLittle NO3 Formation

NET96: Ratio >= 2Excess AmmoniaNO3 Formation

NWRMC

NET96

Given the order of magnitude difference in ammonia emissions,

“reality” lies in between.

Measurements of ammonia and an ammonia emissions model are critical to validation/understanding

of the inorganic chemistry.

(July 14, 1996, 7am)

(July 14, 1996, 7am)

Peak PM2.5 concentrations correspond to peak concentrations of organic aerosols. Organic aerosol concentrations peak in the morning hours due to terpene emissions, chemistry & meteorology. Regional hot spots: CRG & Olympics - Anthropogenic Idaho - Biogenic

5435Error (%)

44-2Bias (%)

0.810.69Index

0.620.57R^2

NWRMCNET96Organic

Aerosols

NWRMC

NET96(July 14, 1996, 7am)

(July 14, 1996, 7am)

Visibility

• In rural areas, scattering of light by aerosol particles accounts for up to 95% of the total light extinction.

• Reconstructed extinction coefficient (bext) calculated by:bext = 0.003 * f(rh) * {[ammonium sulfate] +

[ammonium nitrate]}+ 0.004 * [organic aerosol mass]+ 0.01 * [elemental carbon]+ 0.001 * [fine soil]

• The deciview (dv) linearizes the extinction coefficient:dv = 10 ln(bext/10),

where bext is in units of 1/Mm

NWRMC performed better for all statistics. Visibility impairment in the NET96 solution tended to lie west of the Cascades or occur near urban areas. Both solutions tended to under-predict visibility degradation

1730Error (%)

-1-25Bias (%)

0.770.53Index

0.630.39R^2

NWRMCNET96DeciviewNWRMC

NET96(July 14, 1996, 7am)

(July 14, 1996, 7am)

Columbia River Gorge IMPROVE Site

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

185 186 187 188 189 190 191 192 193 194 195 196 197 198

Julian Day, 1996

PM

2.5

(ng

/m3 )

IMPROVE

NET96

NWRMC

0

500

1000

1500

2000

2500

3000

185 186 187 188 189 190 191 192 193 194 195 196 197 198

Julian Day, 1996

Su

lfat

e (n

g/m

3 )

IMPROVENET96

NWRMC

0

500

1000

1500

2000

2500

3000

185 186 187 188 189 190 191 192 193 194 195 196 197 198

Julian Day, 1996

Nit

rate

(n

g/m

3 )

IMPROVE

NET96

NWRMC

Inorganics at the Columbia River Gorge IMPROVE Site

0

1 0 0 0

2 0 0 0

3 0 0 0

4 0 0 0

5 0 0 0

6 0 0 0

7 0 0 0

8 0 0 0

1 8 5 1 8 6 1 8 7 1 8 8 1 8 9 1 9 0 1 9 1 1 9 2 1 9 3 1 9 4 1 9 5 1 9 6 1 9 7 1 9 8

J u l i a n D a y , 1 9 9 6Or

ganic

Carbo

n (ng

/m3 )

I M P R O V EN E T 9 6N W R M C

0 . 0 0

0 . 0 5

0 . 1 0

0 . 1 5

0 . 2 0

0 . 2 5

0 . 3 0

0 . 3 5

0 . 4 0

0 . 4 5

0 . 5 0

1 8 6 1 8 9 1 9 3 1 9 6

J u l i a n D a y , 1 9 9 6

Ratio

: OC/T

otal P

M2.5

I M P R O V EN E T 9 6N W R M C

Organic Carbonat the Columbia River Gorge IMPROVE Site

0

1 0

2 0

3 0

4 0

5 0

6 0

1 8 5 1 8 6 1 8 7 1 8 8 1 8 9 1 9 0 1 9 1 1 9 2 1 9 3 1 9 4 1 9 5 1 9 6 1 9 7 1 9 8

J u l i a n D a y , 1 9 9 6be

xt (/M

m)

I M P R O V E

N E T 9 6

N W R M C

0

2

4

6

8

1 0

1 2

1 4

1 6

1 8

2 0

1 8 5 1 8 6 1 8 7 1 8 8 1 8 9 1 9 0 1 9 1 1 9 2 1 9 3 1 9 4 1 9 5 1 9 6 1 9 7 1 9 8

J u l i a n D a y , 1 9 9 6

DeciV

iew

I M P R O V E

N E T 9 6

N W R M C

Visibilityat the Columbia River Gorge IMPROVE Site

Summary

• This is the first step in a comprehensive performance evaluation of CMAQ for the Pacific Northwest.

• Two Emission Inventories produced two sets of solutions– order of magnitude difference in NH3 emissions– 3 times greater VOC emissions in NWRMC EI

• Compared the two solutions with measurements at 12 IMPROVE sites.

• NWRMC solution tended to over-predict PM2.5 (bias = 93%) and the NET96 solution tended to under-predict PM2.5 (bias = -15%)

• NWRMC tended to over-predict SO4 and under-predict NO3• NET96 tended to under-predict SO4 and performed well for NO3• Maximum PM2.5 concentrations correspond to peak organic

aerosol concentrations.• The NWRMC solution performs well predicting light extinction

while the NET96 solution under-predicts light extinction.

Recommendations

• Model Development– Improve treatment of organics in aerosol chemistry

• account for different terpene specie yields• organics can modify the water chemistry

– Account for course mode aerosols in extinction calculation

– Incorporate NaCl chemistry– Transfer accumulation mode mass to course

mode (NH4, OC, NO3)– Include crustal species - significant in areas with

airborne dust

Recommendations (cont)

• Emission Inventory Development

– Include emissions from: wind-blown dust, field burning, prescribed fires

– Investigate Biogenic emissions

– NH3

• Two EI solutions presented - “reality” lies inbetween

• NH3 Emissions Model

• Include NH3 from Oceans

• Sensitivity Analysis

– Investigate interdependencies of PM and ozone formation

– Do smaller grid scale studies

Acknowledgements

• States of Oregon, Idaho, Washington - Emission Inventory Development

• EPA Region X - Jeff Arnold, Rob Wilson, Bill Puckett• Canada – Colin Di Cenzo, Weimin Jiang• Washington State University

– Brian Lamb, Shelley Pressley, Jack Chen– Dennis Finn and Candis Claiborn – Spokane Health

Effects Data• NCAR - Alex Guenther - GLOBEIS• PNNL - Guangfeng Jiang – Chemistry Expertise

0

5 0 0

1 0 0 0

1 5 0 0

2 0 0 0

2 5 0 0

3 0 0 0

1 8 5 1 8 6 1 8 7 1 8 8 1 8 9 1 9 0 1 9 1 1 9 2 1 9 3 1 9 4 1 9 5 1 9 6 1 9 7 1 9 8

J u l i a n D a y , 1 9 9 6

Eleme

ntal C

arbon

(ng/m

3 )

I M P R O V E

N E T 9 6

N W R M C

0 . 0 0

0 . 0 5

0 . 1 0

0 . 1 5

0 . 2 0

0 . 2 5

0 . 3 0

0 . 3 5

0 . 4 0

0 . 4 5

0 . 5 0

1 8 6 1 8 9 1 9 3 1 9 6

J u l i a n D a y , 1 9 9 6

Ratio

: EC/T

otal P

M2.5

I M P R O V EN E T 9 6N W R M C

8572Error (%)

7842Bias (%)

0.600.57Index

0.790.73R^2

NWRMCNET96EC

0

5 0 0

1 0 0 0

1 5 0 0

2 0 0 0

2 5 0 0

3 0 0 0

1 8 5 1 8 6 1 8 7 1 8 8 1 8 9 1 9 0 1 9 1 1 9 2 1 9 3 1 9 4 1 9 5 1 9 6 1 9 7 1 9 8

J u l i a n D a y

Fine S

oil (n

g/m3 )

I M P R O V EN E T 9 6N W R M C

0 . 0 0

0 . 0 5

0 . 1 0

0 . 1 5

0 . 2 0

0 . 2 5

0 . 3 0

0 . 3 5

0 . 4 0

0 . 4 5

0 . 5 0

1 8 6 1 8 9 1 9 3 1 9 6

J u l i a n D a y , 1 9 9 6

Ratio

: Fine

Soil/T

otal P

M2.5

I M P R O V EN E T 9 6N W R M C

69172Error (%)

-50152Bias (%)

0.480.14Index

0.21-0.10R^2

NWRMCNET96Fine Soil