Wildfire Emissions and Air Quality: A Case Study on Forest Fires in Southern Orléans, France

Wildfire events are increasing globally due to climate change, with significant adverse impacts on regional air quality and global climate. In the middle of September 2020, a wildfire event occurred in Souesmes (Loir-et-Cher, France), and its plume spread out to 200 km around in the following day as observed by the MODIS satellite. Based on comprehensive field measurements at a suburban atmospheric observation site (~50 km northwest from the wildfire location) in Orléans, young fire plumes were identified. Significant increases in trace gases (CO, CH₄, N₂O, VOCs, etc.) and particles (including black carbon) were found within the BB plumes. Molar enhancement ratios, defined as EF (X) = ∆X/∆CO (where X represents the target species), of various trace gases and black carbon within young plumes were determined accordingly and compared with previous studies. Changes in the ambient ions (ammonium, sulfate, nitrate, chloride, nitrite, etc. in the particle- and gas-phase) and aerosol properties (e.g., aerosol water content, pH) were also quantified and discussed. Furthermore, along with trajectory model (FLEXPART) simulations, we found that the Global Fire Assimilation System (GFAS) may underestimate emissions (e.g., CO) of this small wildfire while other inventories (GFED, FINN) showed significant overestimation. Estimation of emissions of this fire event was conducted and compared with GFAS emissions. Related atmospheric implications are also presented and discussed.