Impacts of Emission Profiles on Urban SOA Formation
Azad Madhu, MYOSEON JANG, University of Florida
Abstract Number: 442
Working Group: Urban Aerosols
Abstract
Secondary organic aerosol (SOA) in urban environments is formed primarily from the photooxidation of a diverse set of alkane and aromatic hydrocarbons (HCs) due to the emissions from anthropogenic activity such as fuel and consumer product usage. For application for SOA simulations at regional scales, parameters that represent SOA formation should be validated against SOA data that is produced from the simultaneous photooxidation of a diverse set of HCs. This study employs parameters of alkane and aromatic HCs to simulate SOA formation from complex anthropogenic hydrocarbon mixtures using the Unified Partitioning and Aerosol Phase Reaction (UNIPAR) model. The model is demonstrated against SOA chamber data collected under various NOx and seed conditions. Mixtures with different fractions of alkanes and aromatics are used to examine the impacts of variable fuel usage (i.e. gasoline vs. diesel) on SOA formation in urban environments. Measured SOA yields are significantly enhanced in lower NOx experiments while they are not significantly impacted by inorganic seed conditions. Model simulations indicate that alkane products represent the majority of SOA formation when aromatic and alkane concentrations are comparable. However, the oxidants formed from the gas phase chemistry of aromatics played an important role by accelerating alkane oxidation.