Aerosol optical properties, such as light absorption and scattering, are important for understanding how aerosols affect the global radiation budget and for comparison with data gathered from remote sensing. It has been established that the optical properties of aerosols are wavelength dependent, although the importance of this wavelength dependence is not well understood. Here, airborne measurements of these optical properties were used to calculate the Angstrom absorption exponent, a parameter that characterizes the wavelength dependence of light absorption by aerosols, and single scattering albedo, which represents the relative magnitude of light scattering to total optical depth (scattering and absorption combined). Aerosols produced by biomass burning in Saskatchewan, Canada in July 2008 and a forest fire in Southern California, U.S. in June 2016 were included in this analysis. These wildfires were sampled by the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) and NASA Student Airborne Research Program (SARP) missions. Aerosol absorption was measured using a particle soot photometer (PSAP) at 470, 532 and 660 nm. Scattering was measured using a 3-wavelength (450, 550 and 700 nm) nephelometer. Angstrom absorption exponents were calculated at 470 and 660 nm and single scattering albedos were calculated at 450 and 550 nm. Results of this study indicate that disregarding the wavelength dependence of aerosol light absorption, as is routinely done in remote sensing measurements of aerosol optical properties, can understate the role of organic carbon components of aerosols.

Presentation Slides: https://www.scribd.com/document/321271583/Investigating-the-Spectral-Dependence-of-Biomass-Burning-Aerosol-Optical-Properties#fullscreen&from_embed