10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Carbon-, Oxygen-, and Size- Resolved Model to Simulate the Microphysics, Chemistry, and Thermodynamics of Biomass Burning Organic Aerosol
ALI AKHERATI, Christopher Cappa, Jeffrey R. Pierce, Shantanu Jathar, Colorado State University
Abstract Number: 1671 Working Group: Aerosol Modeling
Abstract Globally, biomass burning – that includes wildfires, agricultural, prescribed and landfill burning – is an important source of organic aerosol (OA) to the atmosphere. Emissions of biomass burning organic aerosol (BBOA) vary substantially with the fuel type, burn conditions, and ambient conditions and atmospheric mixing and photochemical oxidation are expected to alter the size, mass, and composition of BBOA. Yet, there are large uncertainties when it comes to understanding the physicochemical evolution of BBOA and its consequent impacts on air quality, climate, and human health.
In this work, we will develop a state-of-the-science OA model that combines the two-dimensional statistical oxidation model (SOM) with the TwO-Moment Aerosol Sectional (TOMAS) model.The SOM uses a two-dimensional carbon-oxygen grid to track the gas- and particle-phase chemistry, gas/particle partitioning, and properties of gas- and particle-phase organic precursors and products. The TOMAS model uses two moments, that of number and mass, of the aerosol size distribution to model processes of nucleation, condensation, and coagulation. This updated model, resolved in dimensions of carbon number, oxygen number, and size, will simulate the microphysics, chemistry, and thermodynamics of BBOA and include the following processes: (a) semi-volatile and reactive POA, (b) SOA formation from semi-volatile, intermediate-volatility and volatile organic compounds, (c) multi-phase, multi-generational aging that includes functionalization and fragmentation reactions, (d) low-volatility SOA formation from autoxidation and oligomerization reactions, (e) influence of vapor wall losses encountered in laboratory SOA formation experiments, and (f) phase state of OA. The model will be evaluated against chamber and flow reactor experiments performed at the Fire Laboratory in Missoula, MT as part of the FLAME and FIREX campaigns to identify the most important precursors, pathways, and experimental artifacts that control the size, mass, and composition of BBOA.
Insight from this work will be used to develop models and parameterizations for BBOA in regional and global air quality and climate models.