Evidence that the spectral dependence of light absorption by aerosols is affected by organic carbon

The wavelength dependence of light absorption by aerosols collected on filters is investigated throughout the near‐ultraviolet to near‐infrared spectral region. Measurements were made using an optical transmission method. Aerosols produced by biomass combustion, including wood and savanna burning, and by motor vehicles, including diesel trucks, are included in the analysis. These aerosol types were distinguished by different wavelength (λ) dependences in light absorption. Light absorption by the motor vehicle aerosols exhibited relatively weak wavelength dependence; absorption varied approximately as λ −1 , indicating that black carbon (BC) was the dominant absorbing aerosol component. By contrast, the biomass…