A026-07
Impact of wildfires on formation of secondary organic aerosols over the Amazon rainforest

Monday, 7 December 2020: 19:24
Virtual
ManishKumar Shrivastava1, Quazi Rasool1, Bin Zhao1, Brian John Gaudet2, Shantanu Jathar3, Ali Akherati4, John E Shilling1, Johannes Schneider5, Christiane Schulz6 and Helmut Ziereis7, (1)Pacific Northwest National Laboratory, Richland, WA, United States, (2)Pennsylvania State University, Department of Meteorology and Atmospheric Science, University Park, PA, United States, (3)Colorado State University, Mechanical Engineering, Fort Collins, CO, United States, (4)Colorado State University, Fort Collins, United States, (5)Max Planck Institute for Chemistry, Mainz, Germany, (6)Max Planck Institute for Chemistry, Particle Chemistry Department, Mainz, Germany, (7)German Aerospace Center (DLR), Institute of Atmospheric Physics, Oberpfaffenhofen, Germany
Recorded Presentation
Abstract:
The Amazon rainforest is a unique natural laboratory to understand how human activities and wildfires perturb the formation of secondary organic aerosols (SOA). SOA is a major component of fine aerosols and cloud condensation nuclei (CCN) over the Amazon and affects aerosol-cloud-radiation interactions. We present an integrated model-measurement study of how formation of SOA and its composition changes in the Amazon due to the influence of wildfires during the dry season. We include new developments of multi-phase chemistry of SOA within the Weather Research and Forecasting Model coupled to chemistry (WRF-Chem) and the wildfire plume-rise model based on our latest understanding. Within WRF-Chem, we simulate SOA formation from two major volatile organic compound (VOC) classes found in wildfire emissions: oxygenated aromatics (e.g., phenol, catechol) and heterocyclic compounds (e.g., furan, alkylfurans) based on a simplified volatility basis set (VBS) model derived from fitting environmental chamber experiments. Simulations show that BBSOA concentrations are higher than natural biogenic SOA by a factor of 2-6 over wildfire regions. Wildfires also increase CCN concentrations by more than an order of magnitude compared to background CCN concentrations over hotspots of wildfire emissions regions. In addition, wildfires change atmospheric chemistry over the pristine Amazon by increasing NOx, which catalyzes oxidant production and thus increases biogenic SOA formation by factors of 2-4 compared to the background SOA. Model results are evaluated with aircraft-based field measurements over the Amazon including the Green Ocean Amazon (GoAmazon 2014/5) using the DOE G-1 aircraft and the ACRIDICON-CHUVA field campaign using the German High Altitude and Long-range research aircraft (HALO) during September 2014. This study provides new insights about how wildfires affect the spatial distribution of SOA and CCN over the Amazon.
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