Volatile organic compound (VOC) enhancements and evolution in 2018 and 2019 North American biomass burning plumes

Biomass burning releases large quantities of trace gases and particles into the atmosphere, impacting air quality, weather, and climate. In recent years, North American wildfire seasons have increased in severity and duration, and are predicted to become more extreme as the climate warms. While generally less devastating than wildfires on a local level, prescribed burns and agricultural fires dominate in terms of area burned in North America. Despite this significance, emissions from agricultural fires remain poorly represented in emissions inventories. To better understand and predict the impact of emissions from wildfires, prescribed fires, and agricultural fires, we deployed the NCAR Trace Organic Gas Analyzer (TOGA) on the NSF/NCAR C-130 during WE-CAN (Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption and Nitrogen) in summer 2018 and the NCAR TOGA with a time-of-flight mass spectrometer (TOGA-TOF) on the NASA DC-8 during FIREX-AQ (Fire Influence on Regional to Global Environments and Air Quality) in summer 2019. From these two data sets with over 60 wildland fire plumes and plume segments sampled, and over 30 agricultural fire plumes sampled, we assess fresh plume-average normalized excess mixing ratios (NEMRs) and the NEMR evolution of a large suite of VOCs under different tropospheric background and fire emission regimes. We also investigate the influence of fuels on the fire plume VOC composition, and compare emissions from wildfires, prescribed burns, and agricultural fires.