Biomass-burning smoke episodes in Finland from eastern European wildfires

Biomass burning emissions from intensive wildfires in eastern Europe were observed in Finland in the spring of 2006 and in the late of summers 2006 and 2010. The smoke plumes were detected at three ground-measurement stations around Finland and in the lower troposphere after long-range transport from fire areas. The vertical extent of the smoke was estimated by flight measurements over southern Finland and the measurements were compared with CALIPSO satellite data from 29 July 2010. The history of the arriving air masses was analysed by using backward trajectories and MODIS fire detections. The smoke plumes had elevated concentrations of aerosol particle number, black carbon, CO, CO2, SO2, O-3 and NOx, and the differences as compared with the background air were clear. The smoke was observed to be highly scattering, with a single-scattering albedo of 0.96 +/- 0.01. The median particle size was 60%-250% larger during the plume days than during July August on average, and the growth of smoke particles was observed even after long-range transport of several hundreds of kilometres.