Impact of combustion phase on scattering and spectral absorption of Siberian biomass burning: studies in Large Aerosol Chamber

Impact of Siberian biomass burning phase on optical properties of smoke aerosols is investigated in small-scale fires performed in a Large Aerosol Chamber (LAC). The analyses have revealed the influence of combustion temperature on scattering and light absorption of pine and debris smoke. Scattering in smoldering phase is significantly exceeding the flaming one. Spectral absorption obtained throughout the near-ultraviolet to near-infrared spectral region emphasizes the high absorption Angstrom exponent (AAE), up to 4.4 for fresh debris smoke, and a large fraction of light-absorbing brown carbon (BrC) in the smoldering phase. In opposite, open flaming smoke shows low AAE around 1, typical for high-temperature fossil fuel combustion while mixed fires emit particles absorbing with the intermediate AAE characteristics.