Optical and Particle Sizing Properties of Fresh Biomass Smoke

摘要

In a series of biomass smoke experiments, we measured aerosol optical properties and ultrafine sizing properties during a wildfire event in Colorado and in a laboratory study of fresh biomass smoke emissions. Aerosol optical properties and particle number and mass concentrations were affected by dynamic changes in ultrafine particle concentrations and sizes emitted from freshly emitted biomass smoke. Combustion phase was a key driver, and flaming combustion produced size distributions shifted toward smaller particles compared to smoldering combustion. Likewise, the aerosol optical properties were strongly impacted by these changes in combustion characteristics, affecting the relative importance of light scattering and absorption. Generally, the smoldering dominated fires produced an aerosol dominated by larger, more purely light scattering particles while flaming combustion produced more strongly absorbing, smaller particles (soot-like). Microphysical properties including the particle size distribution and how this impacts light scattering and absorption are key variables in determining smoke impacts on human health, visibility, climate and compliance with regulatory requirements.