Wildfire smoke in the Siberian Arctic in summer: Source characterization and plume evolution from airborne measurements

Abstract

We present airborne measurements of carbon dioxide (CO2), carbon monoxide (CO), ozone (O3), equivalent black carbon (EBC) and ultra fine particles over North- Eastern Siberia in July 2008 performed during the YAKAEROSIB/ POLARCAT experiment. During a "golden day" (11 July 2008) a number of biomass burning plumes were encountered with CO mixing ratio enhancements of up to 500 ppb relative to a background of 90 ppb. Number concentrations of aerosols in the size range 3.5-200 nm peaked at 4000 cm ?3 and the EBC content reached 1.4 μgm?3. These high concentrations were caused by forest fires in the vicinity of the landing airport in Yakutsk where measurements in fresh smoke could be made during the descent. We estimate a combustion efficiency of 90±3% based on CO and CO2 measurements and a CO emission factor of 65.5±10.8 gCO per kilogram of dry matter burned. This suggests a potential increase in the average northern hemispheric CO mixing ratio of 3.0-7.2 ppb per million hectares of Siberian forest burned. For BC, we estimate an emission factor of 0.52±0.07 gBC kg?1, comparable to values reported in the literature. The emission ratio of ultra-fine particles (3.5-200 nm) was 26 cm?3 (ppb CO) ?1, consistent with other airborne studies. © 2009 Author(s).