Grantee Research Project Results
2004 Progress Report: Source-Oriented Chemical Transport Model for Primary and Secondary Organic Aerosol
EPA Grant Number: R831082Title: Source-Oriented Chemical Transport Model for Primary and Secondary Organic Aerosol
Investigators: Kleeman, Michael J. , Griffin, Robert J. , Clegg, Simon
Institution: University of California - Davis , University of East Anglia , University of New Hampshire
Current Institution: University of California - Davis , University of New Hampshire
EPA Project Officer: Chung, Serena
Project Period: October 1, 2003 through September 30, 2006 (Extended to September 30, 2008)
Project Period Covered by this Report: October 1, 2003 through September 30, 2004
Project Amount: $450,000
RFA: Measurement, Modeling, and Analysis Methods for Airborne Carbonaceous Fine Particulate Matter (PM2.5) (2003) RFA Text | Recipients Lists
Research Category: Particulate Matter , Air Quality and Air Toxics , Air
Objective:
The objective of this research project is to model the formation of secondary organic aerosol (SOA) using a state-of-the-science air quality model and to determine source contributions to primary organic aerosol (POA) and SOA concentrations in Los Angeles, the San Joaquin Valley, and St. Louis. The four major objectives of the research project are:
- Objective 1: Determine if the treatment of the aerosol as an internal mixture in bulk equilibrium with the surrounding gas phase biases SOA calculations by appropriately adapting and inserting the SOA module Model to Predict the Multiphase Partitioning of Organics (MPMPO) into the externally mixed source-oriented chemical transport model.
- Objective 2: Determine the likely effects of interactions between inorganic (salt) and soluble organic aerosol components on both SOA yield and the water content of the aqueous aerosols.
- Objective 3: Predict the concentration of total organic aerosol, POA, and SOA concentrations at Supersite locations in Los Angeles, the San Joaquin Valley, and St. Louis.
- Objective 4: Calculate source contributions to POA and SOA concentrations using the source-oriented model and compare calculations for POA to statistical source apportionment calculations to verify the accuracy of model results.
Progress Summary:
Objective 1
The University of New Hampshire team led by Dr. Griffin has produced the second generation of the Caltech Atmospheric Chemistry Mechanism (CACM) gas-phase chemical mechanism and the MPMPO thermodynamic model that now includes the partitioning of 39 semi-volatile organic species into both an organic and aqueous particle phase while considering appropriate activity coefficient calculations. The University of California-Davis (UCD) research team spent Year 1 of the project validating the performance of the source-oriented, externally mixed model and incorporating the CACM and MPMPO models into this framework (Figure 1).
Figure 1. (a) 24-hour Average PM2.5 SOA Concentrations Predicted by the UCD/CIT Source-Oriented External Mixture Model Using the Updated Version of CACM and MPMPO on September 9, 1993. The simulation included 10 different types of primary particles each with 15 sizes. (b) Reduction In Predicted 24-hour Average PM2.5 SOA Concentrations Under Identical Conditions When the Model Is Formulated as an Internal Mixture. Units are μg m-3.
Objective 2
Work on Objective 2 will start in Year 2 of the project (as scheduled).
Objective 3
The meteorological and emissions inputs needed to simulate air quality in the San Joaquin Valley during the California Regional PM10/PM2.5 Air Quality Study (CRPAQS) fields study (corresponding to activities at the Supersite located in Fresno) have been assembled by the UCD research team. Air quality fields that will provide initial/boundary conditions for the calculation currently are being assembled. Simulations for the CRPAQS episode will commence early in 2005.
The first set of equipment needed to run the next generation of the CACM and MPMPO models over the large size and time domains associated with CRPAQS and St. Louis has been purchased. Networking components have been purchased and tested to measure anticipated communication bandwidth. Computing components for 64 additional computers have been purchased and currently are being assembled. The size of the system will continue to be expanded during Years 2 and 3 of the research project to support expanded model calculations.
Objective 4
Source apportionment results from the UCD/California Institute of Technology (CIT) air quality model and the Chemical Mass Balance (CMB) model have been directly compared for air quality episodes that occurred in California’s South Coast Air Basin (SoCAB) on September 7-9, 1993, and the SJV on January 3-5, 1996, by the UCD research team. Figure 2 illustrates that the two models show strong agreement for the predicted concentration of PM2.5 total organic mass and PM2.5 mass for a variety of sources. This result confirms the ability of the UCD/CIT model to perform source apportionment calculations under varying conditions in different airsheds.
Figure 2. Correlation Between CMB and UCD/CIT Estimates for PM2.5 Total Organic Mass and PM2.5 Total Mass for the SoCAB (September 9, 1993) and the San Joaquin Valley (January 6, 1996). Closed symbols correspond to the SoCAB, whereas open symbols correspond to the SJV. Wood smoke was found only in the San Joaquin Valley.
Future Activities:
Objective 1
We will compare the more detailed SOA module to the measurement and surrogate module.
Objective 2
We will start work on Objective 2 in Year 2 of the project.
Objective 3
We will assemble the input fields required for modeling in the SoCAB and in the St. Louis region during Supersite activities during Year 2 of the project.
Objective 4
We will repeat this analysis for Supersite locations where CMB calculations have been carried out. St. Louis is of particular interest, as 1 full year of CMB results are available at this location.
Journal Articles on this Report : 4 Displayed | Download in RIS Format
| Other project views: | All 28 publications | 13 publications in selected types | All 13 journal articles |
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Chen J, Griffin RJ. Modeling secondary organic aerosol formation from oxidation of α-pinene, β-pinene, and d-limonene. Atmospheric Environment 2005;39(40):7731-7744. |
R831082 (2004) R831082 (2005) R831082 (2006) R831082 (2007) R831082 (Final) |
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Griffin RJ, Dabdub D, Seinfeld JH. Development and initial evaluation of a dynamic species-resolved model for gas phase chemistry and size-resolved gas/particle partitioning associated with secondary organic aerosol formation. Journal of Geophysical Research – Atmospheres 2005;110(D5):D05304 (16 pp.). |
R831082 (2004) R831082 (2005) R831082 (2006) R831082 (2007) R831082 (Final) |
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Held T, Ying Q, Kleeman MJ, Schauer JJ, Fraser MP. A comparison of the UCD/CIT air quality model and the CMB source-receptor model for primary airborne particulate matter. Atmospheric Environment 2005;39(12):2281-2297. |
R831082 (2004) R831082 (2005) R831082 (2006) R831082 (2007) R831082 (Final) |
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Ying Q, Kleeman MJ. Source contributions to the regional distribution of secondary particulate matter in California. Atmospheric Environment 2006;40(4):736-752. |
R831082 (2004) R831082 (2005) R831082 (2006) R831082 (2007) R831082 (Final) |
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Supplemental Keywords:
secondary organic aerosols, SOA, source-oriented chemical transport model, source apportionment, inorganic/organic interactions, gas-phase chemistry, secondary particulate matter, air quality model, primary organic aerosol, POA,, RESEARCH, RFA, Air, Ecosystem Protection/Environmental Exposure & Risk, Scientific Discipline, particulate matter, Air Quality, Environmental Chemistry, Engineering, Chemistry, & Physics, Analytical Chemistry, Monitoring/Modeling, Air Pollution Effects, air toxics, Environmental Engineering, Environmental Monitoring, Monitoring, aerosol particles, health effects, source oriented CMT, atmospheric dispersion models, secondary organic aerosol, particle size, air sampling, gas chromatography, mass spectrometry, carbon particles, emissions, monitoring stations, air quality modeling, measurement methods, human exposure, modeling studies, secondary organic aerosols, thermal desorption, particulate matter mass, air quality model, carbon aerosols, aerosol analyzers, particle phase molecular markers, air quality models, atmospheric particulate matter, transport modeling, particle dispersion, human health effects, atmospheric measurements, modeling, monitoring of organic particulate matterProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.