U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division Columbus Day 2010 Prakash Bhave U.S. Environmental Protection Agency CMAS Conference Chapel Hill, North Carolina Simulating PM 2.5 with CMAQ A Decade in Review Acknowledgements: many EPA colleagues & external collaborators

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division 1 Motivating Questions 1.Has CMAQ performance for PM 2.5 improved? 2.Which refinements to the modeling system contributed most?

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division Chem/Aero Processes MET Processes Source/Sink Processes Processes Affecting Modeled PM 2.5 Potential to Improve Model Performance HIGH LOW Availability of Lab or Field Measurements SPARSEABUNDANT Emissions SOA PBL Height Nucleation N 2 O 5 /NO 3 ˙ HetChem Temp, RH Clouds Precip WS, WDIR Wet Removal Dry Dep OC Aging SO 4 AqChem Aerosol Thermo Gas Mechs Coagulation

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division 3 Motivating Questions 1.Has CMAQ performance for PM 2.5 improved? 2.Which refinements to the modeling system contributed most? 3.What PM 2.5 problems remain? See Heather Simon’s talk here at 10:00am today See George Pouliot’s talk tomorrow at 10:40am in Redbud Rm See Heather Simon’s talk tomorrow at 11:20am, right here

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division 4 Historical & Regulatory Context Photochemical air quality models of PM 2.5 size & composition –Major developments: 1975 – 2000 –Limited applications: 2-day episodes, small domains By 2000, new U.S. regulations warranted nationwide PM 2.5 simulations for full-year periods –1997: EPA issues PM 2.5 standard (15 μg m -3 annual avg.) –1999: Regional Haze Rule issued April 2001: EPA completed 1 st full-year simulation across U.S. –CMAQ version 4.1 –Simulation period: 1996 –Meteorology: MM5 with 23 vertical layers –Horizontal grid size: 36 km –Vertical grid: 8 layers, 150m lowest layer –4 quarters run concurrently on 4 CPUs for 14 days Enterprise 450 Sun Workstations (400 MHz) See posters in the lobby: Wyat Appel (12km U.S.) Pius Lee (4km U.S. domain)

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division 5 NMB = 8% CMAQ v4.1 Evaluation Observations (IMPROVE network) 1996 Annual-Average PM 2.5 (μg m -3 ) Model Results (CMAQ) Plot provided by C. Jang

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division 6 CMAQ v4.1 Evaluation Observations (IMPROVE) PM 2.5 Components (μg m -3 ) Model Results (CMAQ) NO 3 SO 4 OC Implications: R&D efforts should focus on improving CMAQ for NO 3 (winter) OC (summer) Plot provided by C. Jang

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division 7 Winter NO 3 - – Success! IMPROVE Observations PM 2.5 Nitrate (μg m -3 ) Winter 2002 – 2006 CMAQ v4.7 Winter nitrate problem “solved” by improving: –Deposition algorithms –Meteorological input –Emissions input (NH 3 ) –Chemical mechanism (N 2 O 5 hydrolysis) Gilliland et al. Atmos.Env Davis et al. ACP 2008

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division 8 Summer Organic PM Moderate Success 2004 – 2006: Assess and Improve POA 2005 – 2008: Revise SOA Treatment

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division 9 Estimate Wildfire Emissions 2004: wildfire emissions added to U.S. National Emission Inventory (NEI) based on state- and month- specific acreage burned More recent inventories use satellite observations to allocate fire emissions to specific grid cells and time periods where burns occurred (e.g., Roy et al., 2007) CMAQ ÷ Observed Concentration 1999 NEIv11999 NEIv3 Bhave et al. ES&T 2007

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division 10 SOA: Fundamental Research 2000 – 2008: EPA recognized need for SOA research –Science To Achieve Results (STAR) grant program –Funded 25+ projects totalling >$10M –Grantees include: Seinfeld, Pankow, Robinson, Donahue, Jimenez, Turpin, & many more –“Unsung heroes” – Darrell Winner, Sherri Hunt Results –New formation pathways elucidated –SOA yields better understood

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division 11 Organic PM 2.5 high-yield aromatics long alkanes ANTHROPOGENIC EMISSIONS low-yield aromatics ATOL1, ATOL2 AXYL1, AXYL2 SV_TOL1 SV_TOL2 ∙OH/NO SV_XYL1 SV_XYL2 ∙OH/NO monoterpene BIOGENIC EMISSIONS SV_TRP1 SV_TRP2 O 3 P, NO 3 ∙OH,O 3 ATRP1, ATRP2 Non-volatile EMISSIONS POA AALK SV_ALK ∙OH Pathways do not contribute to SOA SV_ISO1, SV_ISO2 SV_SQT O 3,O 3 P, or NO 3 ∙OH ∙OH,O 3, or NO 3 isoprene sesquiterpenes ASQT AISO1, AISO2 AISO3 H+H+ benzene ABNZ1, ABNZ2 SV_BNZ1 SV_BNZ2 ∙OH/NO AXYL3 ATOL3 ABNZ3 ∙OH/HO 2 AOLGB AOLGA AORGC ∙OH dissolution cloud water glyoxal methylglyoxal VOCs EMISSIONS CMAQ v4.7 Carlton et al. ES&T in press

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division 12 Organic PM – Moderate Success Summer OC problem mitigated by: –Improving emissions input (wildfires, biogenic VOC) –Upgrading SOA treatment to match the state of the science (2008) PM 2.5 Components (μg m -3 ) IMPROVE Observations (2002 – 2006) CMAQ v4.7 NO 3 SO 4 OC

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division 13 Motivating Questions – Revisited 1.Has CMAQ performance for PM 2.5 improved? 2.Which refinements to the modeling system contributed most?

U.S. EPA Office of Research & Development, Atmospheric Modeling & Analysis Division 14 Conclusions Model performance has improved substantially! I’ve reviewed 8 major refinements to the modeling system. →Meteorology inputs (2) →Emissions & deposition (4) →Atmospheric chemistry (2) PM 2.5 Components (μg m -3 ) IMPROVE Observations (2002 – 2006) CMAQ v4.7 NO 3 SO 4 OC