WRAP Regional Modeling Center, Attribution of Haze Meeting, Denver CO 7/22/04 Introduction to the the RMC Source Apportionment Modeling Effort Gail Tonnesen, University of California, Riverside Tom Moore, Western Governors’ Association Who else? WRAP Attribution of Haze Meeting, Denver, CO July 22, 2004

WRAP Regional Modeling Center, Attribution of Haze Meeting, Denver CO 7/22/04 AoH Work Group Deliverables Geographic source areas of emissions that contribute to impairment at each mandatory federal Class I area (also including existing and potential tribal Class I areas); Mass and species distributions of emissions by source categories within each contributing geographic source area; and The amount of natural and manmade emissions affecting each Class I area

WRAP Regional Modeling Center, Attribution of Haze Meeting, Denver CO 7/22/04 Definitions Sensitivity to a source: predicts the effect of a change in emissions on the change in concentration at a receptor site: –Sensitivities can be non-linear and non-additive. –Can result in underestimate of importance of small sources. Source attribution: explain PM concentration at a receptor site by indicating the sources that contribute. Source Apportionment: to divide and share out according to a plan. (Apportion responsibility?)

WRAP Regional Modeling Center, Attribution of Haze Meeting, Denver CO 7/22/04 Conceptual Model Reality Attribution of Haze Project Existing 2002 EIs Receptor Modeling Analyses Gridded Dispersion Model Analyses Apportionment Attribution Pure, Idle Speculation

WRAP Regional Modeling Center, Attribution of Haze Meeting, Denver CO 7/22/ AoH Project Data Sources Source apportionment modeling simulations from the Regional Modeling Center Receptor-oriented source contribution analyses of aerosol and meteorological monitoring data from the Causes of Haze Assessment project Existing and refined emissions inventories from the Dust, Emissions, and Fire Forums Special-purpose source attribution studies such as BRAVO, et cetera EPA technical guidance documents and analyses Journal publications, and workshop/conference reports addressing emissions and visibility impairment

WRAP Regional Modeling Center, Attribution of Haze Meeting, Denver CO 7/22/ AoH Project Deliverables Identify: –Geographic source areas of emissions that contribute to impairment at each mandatory federal and tribal Class I area –Mass and species distributions of emissions by source categories within each contributing geographic source area –The amount of natural and manmade emissions affecting each Class I area

WRAP Regional Modeling Center, Attribution of Haze Meeting, Denver CO 7/22/ AoH Project Deliverables Provide: –Documentation of the assumptions, methods, and uncertainties used in the integrated analyses of modeling, monitoring, and emissions data. –Succinct, clear summaries for policymakers, of the estimated areas and sources of impairment for each Class I area, including the associated uncertainty

WRAP Regional Modeling Center, Attribution of Haze Meeting, Denver CO 7/22/04 RMC Activities for AoH The RMC work plan includes support for AoH in two modeling studies: –Source apportionment modeling uses tracers in CMAQ to attribute mass at receptor sites to emissions source regions & source categories. Budget in 2004 work plan: $61,717 –Modeling of natural emissions and visibility in CMAQ. Budget in 2004 work plan: $18,194 Related RMC activities: –CMAQ sensitivity simulations with alternate emissions scenarios, e.g., fires can be used to assess source attributions.

WRAP Regional Modeling Center, Attribution of Haze Meeting, Denver CO 7/22/04 Lessons of 309 work WRAP states have low PM and relatively good visibility. No single control measure in 309 produced large visibility benefits: –Long-range transport (BC) and natural PM believed to be important contributors. –Several PM species contribute to poor visibility. –Difficult to get large improvements in visibility.

WRAP Regional Modeling Center, Attribution of Haze Meeting, Denver CO 7/22/04 CMAQ TSSA Results Results are presented in two ways: –Animations of plumes of PM produced from emissions of individual source categories and source regions –Bar plots showing largest species contributor at each site. Regions are resolved at the state level and by major emissions category: Area, Point, Mobile, Fire Results show small contributions from multiple source and low concentrations. Results indicate that local emissions are dominant.

WRAP Regional Modeling Center, Attribution of Haze Meeting, Denver CO 7/22/04 Current Results CMAQ Tagged species source apportionment simulations are being completed for 2002: –Results are currently complete for January & July. –Model requires many tracers to track reactive species, especially NOy and NO3. Results in large data sets and slow run times. –Multiple simulations needed to apply tracers to all species of interest. –Although expensive, this is much less costly than running large numbers of sensitivity simulations.