Modeling Aerosol Formation 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, 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 NET96NWRMCNET96 (BEIS2) NWRMC (GLOBEIS) NET96NWRMC Isoprene OLT Terpenes Total VOC NH NOx Biogenic VOC emissions are 2.8 times higher in the NWRMC EI MBO (lumped into OLT) accounts for 14% of the VOC’s in the NWRMC Terpene 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 (%) Index R^2 NWRMCNET96 Total 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) 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) Error (%) Bias (%) Index R^2 NWRMC NET96 NWRMC NET96 NO3SO2 Inorganic Aerosols (July 14, 1996, 7am) NWRMC NET96

Ratio: [NH4+NH3]/SO4 July 14, 1996, 7am  NWRMC: Ratio varied about 1 SO4 Formation Dominates Little NO3 Formation  NET96: Ratio >= 2 Excess Ammonia NO3 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)

 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 (%) Index R^2 NWRMCNET96Organic Aerosols NWRMC NET96 (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 = * f(rh) * {[ammonium sulfate] + [ammonium nitrate]} * [organic aerosol mass] * [elemental carbon] * [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 (%) -25Bias (%) Index R^2 NWRMCNET96Deciview NWRMC NET96 (July 14, 1996, 7am)

Columbia River Gorge IMPROVE Site

Inorganics at the Columbia River Gorge IMPROVE Site

Organic Carbon at the Columbia River Gorge IMPROVE Site

Visibility at 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

8572Error (%) 7842Bias (%) Index R^2 NWRMCNET96EC

69172Error (%) Bias (%) Index R^2 NWRMCNET96Fine Soil