Emerging Science EPA’s ORD Supports Regional Haze Program RPO National Technical Meeting June 9-10, 2005 Denver, CO Fred Dimmick, Chief Process Modeling Research Branch Human Exposure and Atmospheric Sciences Division Fred Dimmick, Acting Chief Process Modeling Research Branch Human Exposure and Atmospheric Sciences Division

Agenda Quick overview of ORD atmospheric sciences activities Related to regional haze Only a portion of research Introduce “posters” from EPA’s BOSC review and Science Forum Take questions now (or afterwards)

Receptor models estimate contribution of different source types to ambient PM concentrations Sample Screens from EPA PMF and EPA Unmix

Receptor models estimate contribution of different source types to ambient PM concentrations Recent Enhancements Focused on approaches for guiding decisions in applying models and interpreting results. Include development of statistics summarizing uncertainty in modeled solutions. Future Directions Enhancement of receptor models through EPA STAR grants. developing the next generation of receptor models assessing the accuracy and precision of the existing models. Enhancements are being folded into a suite of multivariate receptor models that EPA is freely distributing to the user community.

PM Supersites Program Sampling and analysis methods to measure the chemical and physical characteristics of PM and important precursor species, Enhanced temporal and compositional characterization that complements routine ambient air monitoring networks, and Insights into policy relevant phenomena that corroborate current policies, cause rethinking and modification, and provide direction for future policy formulation. Baltimore Fresno Los Angeles New York Houston Atlanta St. Louis Pittsburgh

Policy Relevant Synthesis of Research PM Supersites Program Policy Relevant Synthesis of Research -- 17 Science/Policy Relevant Questions -- Methods (Qs 1-3) Characterization (Qs 4- 8) Receptor-Based Models and Emissions-Based Chemical Transport Models (Qs 9-11) Atmospheric Processes (Qs 12 – 15) Emissions Estimates (Q 16)

CMAQ Research Goals … Identify PM components that contribute to model performance strengths and weaknesses for total PM2.5. Target and diagnose sources of error for PM component predictions with the highest level of uncertainty Determine role of input sources of error (e.g., emissions, meteorology) versus uncertainties in modeled processes Evaluate model responses and sensitivities to emission changes.

Secondary Organic Aerosol (SOA) EXPERIMENTAL ATMOSPHERIC CHAMBER Objectives Identify the major SOA precursors Identify tracer compounds for the major SOA precursors Determine reaction mechanisms for SOA formation Improve treatment of SOA in CMAQ Use the smog chamber to generate atmospherically relevant air mixtures for exposure studies

SOA Tracer Compounds from Laboratory and Field Samples

Secondary Organic Aerosol (SOA) - Experimental Chamber Future Directions Continue comparing chamber concentrations and compositions of SOA formed with atmospherically relevant individual and mixtures hydrocarbons irradiated in the presence of NOx and SO2 with model results for proposed SOA formation mechanisms. Identify SOA tracer compounds for sesquiterpenes. Continue measuring and refining values for l for SOA precursors and use them to estimate contributions of SOA precursors to ambient PM2.5 concentrations. Assess whether SOA yields in complex hydrocarbon mixtures are additive. Work with modelers to develop the CMAQ version of the PM chemistry model.

Human Exposure and Atmospheric Sciences Division Linda Sheldon, Director Tim Watkins, Deputy Director Source attribution and apportionment Shelly Eberly (Eberly.Shelly@epa.gov) Gary Norris (Norris.Gary@epa.gov) PM Supersites and Ambient PM Methods Paul Solomon Bob Vanderpool (Vanderpool.Robert@epa.gov) CMAQ Alice Gilliland (Gilliland.Alice@epa.gov) Atmospheric chamber Ed Edney and Tad Kleindienst Fred Dimmick (Dimmick.Fred@epa.gov) Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.