Evolution of Atmospheric Brown Carbon in Wildfire Smoke Plumes during the 2019 FIREX-AQ and 2023 AEROMMA Field Campaigns

JHAO-HONG CHEN, Umamaheshwara Rao Puttu, Robert J. Yokelson, Vanessa Selimovic, Nicholas Wagner, Joshua P. Schwarz, Han N. Huynh, Adam Ahern, Ming Lyu, Lu Xu, Washington University in St. Louis

     Abstract Number: 252
     Working Group: Aerosol Chemistry

Abstract
Atmospheric brown carbon (BrC) is the light-absorbing fraction of organic aerosol (OA), a major component of particulate matter (PM) emitted from wildfires and plays an important role in climate models to account for global radiative forcing. The evolution of BrC is still not well understood due to several factors, including the variation of wildfire emissions from various fuel types and variable combustion conditions, and the limitation of the assumption of the pseudo-Lagrangian sampling from aircraft measurements. To account for the impacts of fuel types, we group the fuel types into several clusters according to their similarities. We find that BrC from different fuel types behaves differently, which partly explains the observed variability of BrC evolution in the field. Further, to mitigate the fluctuations from emission sources, we normalize the measured BrC in the field by the estimated BrC emission ratio based on the 2016 FIREX FireLab study. This method can largely explain the variability of measured BrC during the 2019 FIREX-AQ and 2023 AEROMMA field campaigns. Overall, this study helps constrain the climate model to account for the global radiative forcing by providing a comprehensive information of evolution and lifetime of BrC from wildfires.