Wildfire smoke in the Siberian Arctic in summer: source characterization and plume evolution from airborne measurements
1Laboratoire des Sciences du Climat et de l'Environnement/IPSL, CNRS-CEA-UVSQ, Orme des Merisiers, CEA Saclay, Gif sur Yvette, France
2Norwegian Institute for Air Research, Kjeller, Norway
3Laboratoire d'Aérologie, CNRS-UPS, Toulouse, France
4Institute of Atmospheric Optics, SB-RAS, Tomsk, Russia
5UPMC Univ. Paris 06; Univ. Versailles St-Quentin; CNRS/INSU, LATMOS-IPSL, Paris, France
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 YAK-AEROSIB/POLARCAT experiment. During a "golden day" (11 July 2008) a number of biomass burning plumes were encountered with CO concentration 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 μg m−3. These high concentrations were caused by forest fires in the vicinity of the landing airport in Yakutsk where during the descent measurements in fresh smoke could be made. We estimate a combustion efficiency of 90±3% based on CO and CO2 measurements. The emission factor of CO emitted was 59.6±15.2 g CO per kilogram of dry matter burned, suggesting an increase in the average northern hemispheric CO concentration 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 g BC 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.
The transport of identified biomass burning plumes was investigated using the FLEXPART Lagrangian model. Based on sampling of wildfire plumes from the same source but with different atmospheric ages derived from FLEXPART, we estimate that the e-folding lifetimes of EBC and ultra fine particles (between 3.5 and 200 nm in size) against removal and growth processes are 5.1 and 5.5 days, respectively, supporting lifetimes estimates used in various modelling studies.