Abstract Number: 259 Working Group: Haze in China: Sources, Formation Mechanisms, and Current Challenges
Abstract In this study, a modified SAPRC-11 photochemical mechanism with more detailed treatment of isoprene oxidation chemistry and additional secondary organic aerosol (SOA) formation through surface-controlled reactive uptake of dicarbonyls (glyoxal and methylglyoxal), isoprene epoxydiol and methacrylic acid epoxide was incorporated in the Community Multiscale Air Quality Model (CMAQ) to quantitatively determining the spatial and temporal distribution of SOA in China in the entire year of 2013. The modified model utilizes a precursor-origin resolved approach to determine secondary glyoxal and methylglyoxal produced by oxidation of isoprene and other major volatile organic compounds (VOCs) such as long chain alkanes and aromatic compounds. The anthropogenic emissions are based on the Multi-resolution Emission Inventory for China (MEIC) and the biogenic emissions are estimated using the Model of Emissions of Gases and Aerosols from Nature (MEGAN) v2.1. Seasonal variations of SOA in different regions of China will be determined and regions with high SOA concentrations will be identified. In each region, relative contributions of different precursors to SOA will be quantified. The predicted PM2.5 concentrations will be evaluated using all available PM2.5 measurements across China and predicted SOA concentrations will be evaluated using published oxygenated organic aerosol (OOA) concentrations derived from data collected by aerosol mass spectrometers (AMS). This is the first regional SOA modeling study which uses the best available emission data and includes recent updated understanding of SOA formation pathways.