Observations of wildfire volatile organic compound emissions and urban ozone precursors

Anthropogenic emissions have and continue to degrade air quality and alter chemical regimes in the atmosphere. Emissions of greenhouse gases have increased global temperatures, contributed to increasingly arid conditions, and exacerbated wildfire seasonal lengths and intensities. Wildfires emit a wide array of carcinogenic, highly reactive volatile organic compounds (VOCs). Urban emissions of oxides of nitrogen leads to the formation of secondary pollutants like ozone and organic aerosols. Prediction and mitigation of pollution events requires the understanding of complex VOC oxidation pathways. This work employs ground observations to further constrain VOC emissions from wildfires, assess the accuracy of ground-monitoring network HCHO measurements and determine temporal changes in urban HCHO concentrations, and evaluate the accuracy of satellite products when monitoring NO2 over airports. We use measurements from a proton transfer reaction time-of-flight mass spectrometer to develop emission factors (EFs) for 15 species for an understudied temperate forest biome in New South Wales, Australia. We conclude that EFs are applicable across geographically different but analogous biomes for modeling purposes. We then evaluate the precision and accuracy of three fast measurement, in-situ HCHO monitors and compare with observations from the TO-11A methodology at a photochemical assessment monitoring station in Atlanta. We find that TO-11A measurements are biased low, and that decreases in HCHO concentrations since 1999 are small. Finally, we use NO2 vertical profile measurements from a Pandora spectrometer and profile estimates from chemistry transport model to recalculate satellite retrievals. We find the recalculated quantities are biased low relative to independent ground observations.

Date

2024-08-01

Resource Type

Text

Resource Subtype

Dissertation

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