Abstract Number: 352 Working Group: Regional and Global Air Quality and Climate Modeling
Abstract Organic aerosols (OA) are a major component of atmospheric particulate matter (PM), which has a complex effect on climate, both globally and regionally. PM is also detrimental to human health in both urban and rural regions. Some OA mass is emitted directly from industrial, vehicular and cooking sources, which are relatively well characterized. However, secondary organic aerosols (SOA) formed from gaseous precursors are relatively poorly understood, which makes it difficult to assess their impact on health and climate. A customized box model was developed to evaluate several chemical parameterizations for their ability to simulate SOA formation rates and oxygen-to-carbon ratios resulting from the oxidation of volatile organic compounds (VOCs), semivolatile organic compounds (SVOC), and intermediate volatility organic compounds (IVOCs) emitted from the Athabasca oil sands. The model results are compared to measurements taken from an aircraft during the summer of 2013. Several SOA parameterizations are implemented in the box model and evaluated against observations of the formation and evolution of SOA in a plume of emissions up to 120 km downwind of the oil sands operations. SVOC and IVOC emission factors from the oil sands are isolated as a function of black carbon emissions. By constraining emissions using the aircraft measurements and modeling their oxidation using published parameterizations with no additional tuning, we found good agreement between measured and modeled OA concentrations along two Lagrangian flights. The results of this study are currently being incorporated into a version of the 3-D Global Environmental Multi-scale – Modeling Air Quality and Chemistry (GEM-MACH) model that simulates the evolution of primary OA and SOA formed from VOCs and IVOCs emitted by the continued extraction of bitumen in Northern Alberta.