AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Translating Environmental Chamber Data for Secondary Organic Aerosol for Use in Atmospheric Models
CHARLES HE, Ali Akherati, Christopher Cappa, Jeffrey R. Pierce, ManishKumar Shrivastava, Benjamin Murphy, Shantanu Jathar, Colorado State University
Abstract Number: 703 Working Group: Aerosol Chemistry
Abstract For more than three decades, environmental chambers have been used as tools to study secondary organic aerosol (SOA) formation from volatile organic compounds (VOCs). Yet, SOA parameterizations based on chamber data may not appropriately account for the influence of multigenerational aging, losses of vapors to the chamber walls, varying NOX levels, and phase state of the condensing SOA. In addition, parameterizations that are based on single compound studies may poorly represent the SOA formation from a mixture of lumped VOCs in atmospheric models. To address these problems, we used a state-of-the-science model to simulate the multigenerational chemistry, phase-dependent dynamic gas/particle partitioning, and vapor wall loss effects on SOA formation during chamber experiments. The chemistry and thermodynamic properties were modeled using the Statistical Oxidation Model (SOM) and the gas/particle partitioning kinetics were modeled using the TwO Moment Aerosol Sectional (TOMAS) model. The SOM-TOMAS model will be used to develop SOA parameters for a host of anthropogenic (e.g., alkanes, aromatics) and biogenic (e.g., isoprene, monoterpenes) VOCs based on historical chamber data. Parameters will be determined by fitting the time series for SOA mass concentrations, and when available, SOA O:C and thermodenuder-based volatility data. The SOM-TOMAS model will be used with those parameters to perform atmospherically relevant (i.e., lower seed and OH concentrations, no vapor wall losses) simulations to study the evolution of SOA mass yields and composition over several days. Sensitivity simulations will be performed to systematically investigate the role of aging, NOX, and phase state. Finally, those simulations will be used to develop updated volatility basis set fits for use in atmospheric models.