10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Secondary Organic Aerosol (SOA) Phase State-Relevant Properties: Evaluation of Impacts in the Southern Great Plains Using CMAQ
ANNMARIE CARLTON, Ying Li, Manabu Shiraiwa, James Smith, Sergey Nizkorodov, Marc Carreras-Sospedra, Donald Dabdub, University of California, Irvine
Abstract Number: 1590 Working Group: Aerosol Chemistry
Abstract Secondary organic aerosol (SOA) is a dominant contributor to the atmospheric particle matter burden. Historically, atmospheric models struggle to accurately reproduce field measurements of SOA surrogates. Discrepancies may arise from model approaches that describe gas-to-particle partitioning for SOA formation with two assumptions: instantaneous thermodynamic equilibrium, and all organic material is equally miscible. Recent laboratory and field evidence indicates these assumptions are not always valid, in part due to kinetic limitations on partitioning imposed by SOA phase state. SOA transitions between amorphous and semi-solid states as a function of chemical composition, relative humidity and temperature. We calculate the glass transition temperature (Tg), hygroscopicity parameter (κ), and the Gordon-Taylor constant for SOA predicted with the Community Multiscale Air Quality (CMAQ) model and investigate impacts on SOA viscosity. We focus on predictions at the Department of Energy (DOE) monitoring site in the Southern Great Plains in Oklahoma, a location that provides robust chemical climatology for particle properties relevant to SOA phase state. We also compare CMAQ predictions for the intensive observing period during the Holistic Interaction of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) field campaign in 2016.