EC-09. Using observations of Western U.S. wildfire smoke to improve fire emissions in air quality forecasting models

The spatial and seasonal reach of fire and their subsequent air quality impacts are likely to increase due to a warmer and drier climate in the Western U.S. during the 21st century. These trends, combined with rising numbers of humans living in the urban-wildland interface, are likely to result in increases in population exposure to fire activity and poor air quality episodes. Air quality forecasts using regional chemical models provide key information for affected communities and smoke management efforts, yet many models fail to accurately predict ozone (O3) and fine particulate matter (PM2.5) levels during fire events. Our research utilizes the dataset from the 2019 NOAA/NASA Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field campaign to improve process-level understanding and model representations of fire emissions, plume rise, and chemistry, with the aim of developing a better capability to predict air quality and weather in fire-affected regions. We simulate the FIREX-AQ period with the Weather Research and Forecasting with Chemistry (WRF-Chem) model. Model fire emissions amounts are constrained by observation-based estimates, and emission factors (EFs) are updated based on laboratory and field observations. Simulated trace gas and aerosol fields and plume injection heights are compared with observations from FIREX-AQ and surface network observations. Modeled trace gas mixing ratios and aerosol concentrations better correspond to observed values when FIREX-AQ EFs are used. The simulations are used to explore chemical and physical processes affecting O3 and PM2.5 amounts. Synergies with chemical data assimilation research and air quality forecasting are discussed.