Airborne measurements of aerosols and carbon dioxide during a prescribed fire experiment at a boreal forest site

During a prescribed fire experiment, CO2 and particle number concentrations, light scattering and absorption coefficients were measured from a Cessna 172 airplane. Peak number concentrations were (3 +/- 1) x 10(6) cm(-3) and they decreased faster than what can be explained by coagulation alone. The single-scattering albedo of particles grew from the values of 0.4 +/- 0.1 closest to the emissions to the values of 0.8 +/- 0.1 at the distance of 400 m from the emissions. The mean Angstrom exponent of absorption, 1.70 +/- 0.24, is in line with the published spectral absorption values of wood-smoke aerosol. The estimated emission factors were 1600 +/- 1020, 5.9 +/- 6.3 and 1.4 +/- 1.0 g kg(-1) (dry biomass), for CO2, particulate organic matter and black carbon (BC), respectively, and (4.8 +/- 2.9) x 10(15) particles per kg (dry biomass) for the particle number. The BC emission factor may be overestimated by a factor of about 1.6 +/- 0.2 due to condensation of organics on the filter of the absorption photometer. During the smoldering phase, there were clear indications of new particle formation.