Research Projects

Project at a Glance

Title: Modeling the formation and evolution of secondary organic aerosol during Calnex 2010

Principal Investigator / Author(s): Jimenez, Jose-Luis

Contractor: University of Colorado

Contract Number: 11-305

Research Program Area: Atmospheric Processes

Topic Areas: Field Studies

Research Summary:

Organic aerosols (OA), and specifically secondary organic aerosols (SOA) formed from oxidation of gaseous precursors, constitute a large fraction of the submicron particulate mass and are responsible for significant health and climate effects. Despite their importance, a substantial gap remains between model predictions and field measurements of SOA concentrations, with predictions typically too small by a factor of two to three. The objective of the proposed research is to improve modeling of the concentration, composition and evolution of SOA in California by using measurements from the CalNex 2010 field study to optimize and constrain state-of-the-art SOA models. The improvements to SOA models will be based on a wide variety of measurements that were taken during the largest field study of atmospheric processes over California – CalNex 2010. These include high-resolution time-of-flight Aerosol Mass Spectrometer (HR-ToF-AMS) measurements of aerosol composition taken by the Jimenez Group and supporting measurements of aerosol precursors and other species taken by other research groups at the Pasadena supersite. By employing multi-group data sets, the research team effectively leverages several million dollars’ worth of data collection and analysis work from the CalNex 2010 campaign. State-of-the-art SOA models will be run using SOA precursor and oxidant data as inputs to provide predictions for the concentration, composition and volatility of SOA at the field site; the resulting predictions will be compared against experimentally determined SOA characteristics. Parameters within the models will then be adjusted to provide the best description of the data. Given the scope and the sophistication of the gas-phase and particle-phase measurements carried out during CalNex 2010, the proposed research will test and constrain SOA models at a level of detail that has not been possible before. Results from this work will be used to help identify sources of SOA and improve models that quantitatively predict the evolution of SOA; these improvements will aid in the development of effective strategies to reduce SOA pollution in California and in predictions of future climate change.


For questions regarding research reports, contact: Heather Choi at (916) 322-3893

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