The proposed research seeks to develop a systematic understanding of the fundamental optical and life-cycle properties of biomass-burning aerosols from freshly emitted to several days of aging. The variations in aerosol properties will be quantified as a function of various combustion processes, such as: phase of burning, fuel type, and moisture content; as well as atmospheric processes such as oxidation, relative humidity and condensation of volatile organics. The significance of this research is to improve our understanding of the role that biomass-burning aerosols play in the direct radiative effects. Current models assume a spherical shape for these aerosols, whereas this research will combine laboratory and field experiments focused on the fractal shape of biomass-burning aerosols. This research has the potential to lead to two important societal benefits: reduced uncertainty in direct radiative forcing (DRF) effects from biomass-burning aerosols and the development of modules to enhance K-12 education through internet-based learning. This research and education plan uses the resources of Washington University's Institute for School Partnership (ISP), providing outreach to K-12 students and teachers in underrepresented minority communities.
The proposed research combines a significant theoretical component coupled with well-conceived laboratory experiments. The goal is to develop a look-up-table (LUT) to replace the Mie-theory based modeling efforts currently in use. This study proposes a significant effort aimed at reconciling predicted refractive index and asymmetry parameter determined experimentally and using numerically exact T-matrix codes. If successful, this could lead to transformative understanding of the physical and optic properties of biomass-burning aerosols. Specifically this new knowledge may help reduce uncertainties associated with direct radiative forcing due to biomass-burning aerosols. Datasets resulting from this research will improve parameterization of aerosol radiative transfer interaction in global and regional modeling efforts.
