Mobile Near-Field Measurements of Biomass Burning Volatile Organic Compounds: Emission Ratios and Factor Analysis

Comprehensive measurements of volatile organic compounds (VOCs) and oxygenated VOCs that are emitted from wildfires are important inputs for constraining ozone and secondary organic aerosol formation potential in chemical transport models. Using Vocus proton-transfer reaction mass spectrometer and tunable infrared laser direct absorption spectroscopy instruments on a mobile laboratory during the Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) 2018 and 2019 campaigns, seven different fires over two years were sampled from <10 km away providing extensive chemical composition and aging information about emissions of VOCs and oxidized VOCs from fires. Several of these fires were sampled <300 m from burning fuels, yielding insight into relatively fresh smoke measurements. The emission ratios reported here are statistically consistent with measurements of controlled fires in a laboratory setting. Chemically unique mass spectral signatures of low- and high-temperature pyrolysis are determined from factor analysis while sampling real-world fires burning in heterogeneous stages.