Colloquium: Dr. Arthur J. Sedlacek | Brookhaven National Laboratory

TITLE:  Piecing Together the Lifecycle of Biomass Burning Aerosols:

ABSTRACT: 

Aerosols emitted from wildfires and agricultural burns, collectively referred to as biomass burning (BB), are recognized to perturb Earth’s climate through the “direct” effect (the scattering and absorption of incoming shortwave radiation), the “semi-direct” effect (evaporation of cloud drops and modification of atmospheric dynamics), and “indirect” effects (influencing cloud formation and precipitation). These events are an important aerosol source, providing an estimated 50% of anthropogenically influenced fine carbonaceous particles and are responsible for about 40% of the global atmospheric inventory of black carbon (BC) – the most important particulate warming agent. 
Additionally, the scientific community now recognizes that these events also generate light-absorbing organic compounds, known as brown carbon (BrC). The overall impact of these particles on the atmospheric radiation balance, either forcing the atmosphere to heat or to cool, depends on the abundance, cloud forming activity, and refractive index (specifically the absorption) of emitted primary particles and secondary aerosol species. 

During the summer and fall of 2013, the Department of Energy’s Atmospheric Radiation Measurement (ARM) program sponsored an aircraft study to  investigate the near source evolution (< 5 hrs) of biomass burning aerosol (BBA) particles. This field campaign, known as BBOP (Biomass Burning Observation Project), represents the first time that near source evolution of BB aerosol particles was exclusively targeted with research aircraft. This campaign has provided new insights into the near-source evolution of BBA. Participation in the 2017-18 DOE LASIC (Layered Atlantic Smoke Interactions with Clouds) and 2016-18 NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) campaigns are now complementing our near source work by providing key measurements on very aged (1-2 weeks) biomass burning plumes thereby allowing the unprecedented opportunity to examine the lifecycle of these aerosols. 

I will introduce the importance and associated complexities of biomass burning, talk briefly about how measurements of these events are conducted, and highlight examples of how atmospheric processing can alter smoke aerosols.