Analyzing the Impact of Evolving Combustion Conditions on the Composition of Wildfire Emissions Using Satellite Data
Lindsey D. Anderson (University of Colorado - Boulder)
Barbara Dix (University of Colorado - Boulder)
Jordan Schnell (University of Colorado - Boulder, National Oceanic and Atmospheric Administration)
Robert Yokelson (University of Montana)
J. Pepijn Veefkind (Royal Netherlands Meteorological Institute (KNMI), TU Delft - Atmospheric Remote Sensing)
Ravan Ahmadov (National Oceanic and Atmospheric Administration)
Joost de Gouw (University of Colorado - Boulder)
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Abstract
Wildfires have become larger and more frequent because of climate change, increasing their impact on air pollution. Air quality forecasts and climate models do not currently account for changes in the composition of wildfire emissions during the commonly observed progression from more flaming to smoldering combustion. Laboratory measurements have consistently shown decreased nitrogen dioxide (NO2) relative to carbon monoxide (CO) over time, as they transitioned from more flaming to smoldering combustion, while formaldehyde (HCHO) relative to CO remained constant. Here, we show how daily ratios between column densities of NO2 versus those of CO and HCHO versus CO from the Tropospheric Monitoring Instrument (TROPOMI) changed for large wildfires in the Western United States. TROPOMI-derived emission ratios were lower than those from the laboratory. We discuss reasons for the discrepancies, including how representative laboratory burns are of wildfires, the effect of aerosols on trace gas retrievals, and atmospheric chemistry in smoke plumes.
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