Particle emissions from laboratory combustion of wildland fuels:: In situ optical and mass measurements

Time-resolved optical properties of smoke particles from the controlled laboratory combustion of mid-latitude wildland fuels were determined for the first time using advanced techniques, including cavity ring-down/cavity enhanced detection (CRD/CED) for light extinction and two-wavelength photoacoustic detection for light absorption. This experiment clearly resolves the dependence of smoke properties on fuel and combustion phase. Intensive flaming combustion during ponderosa pine wood (PPW) burning produces particles with a low single scattering albedo of 0.32 and a specific mass extinction efficiency of 8.9 m(2) g(-1). Burning white pine needles (WPN) features a prolonged smoldering phase emitting particles that are not light-absorbing and appear much larger in size with an extinction efficiency approximate to 5 m(2) g(-1). A Mie scattering model was formulated, which estimates the black carbon fraction in the PPW and WPN smoke particles at 66% and 12%, respectively. These observations may refine the current radiative forcing estimates for biomass burning emissions.