Evolution of brown carbon in wildfire plumes

摘要: Particulate brown carbon (BrC) in the atmosphere absorbs light at subvisible wavelengths and has poorly constrained but potentially large climate forcing impacts. BrC from biomass burning virtually unknown lifecycle atmospheric stability. Here, emitted intense wildfires was measured plumes transported over 2 days two main fires, during 2013 NASA SEAC4RS mission. Concurrent measurements of organic aerosol (OA) black (BC) mass concentration, BC coating thickness, absorption Angstrom exponent, OA oxidation state reveal that initial fires largely unstable. Using back trajectories to estimate transport time indicates decayed with a half-life 9 15 h, day night. Although most lost within day, possibly through chemical loss and/or evaporation, remaining persistent fraction likely determines background levels relevant for forcing.