Abstract
Abstract. Chemistry transport models (CTMs) are an indispensable tool for studying and predicting atmospheric and climate effects associated with carbonaceous aerosol from open biomass burning (BB); this type of aerosol is known to contribute significantly to both global radiative forcing and to episodes of air pollution in regions affected by wildfires. Improving model performance requires systematic comparison of simulation results with measurements of BB aerosol and elucidation of possible reasons for discrepancies between them, which, by default, are frequently attributed in the literature to uncertainties in emission data. Based on published laboratory data on the atmospheric evolution of BB aerosol and using the volatility basis set (VBS) framework for organic aerosol modeling, we examined the importance of taking gas-particle partitioning and oxidation of semi-volatile organic compounds (SVOCs) into account in simulations of the mesoscale evolution of smoke plumes from intense wildfires that occurred in western Russia in 2010. Biomass burning emissions of primary aerosol components were constrained with PM10 and CO data from the air pollution monitoring network in the Moscow region. The results of the simulations performed with the CHIMERE CTM were evaluated by considering, in particular, the ratio of smoke-related enhancements in PM10 and CO concentrations (ΔPM10 and ΔCO) measured in Finland (in the city of Kuopio), nearly 1000 km downstream of the fire emission sources. It is found that while the simulations based on a "conventional" approach to BB aerosol modeling (disregarding oxidation of SVOCs and assuming organic aerosol material to be non-volatile) strongly underestimated values of ΔPM10/ΔCO observed in Kuopio (by a factor of 2), employing the "advanced" representation of atmospheric processing of organic aerosol material resulted in bringing the simulations to a much closer agreement with the ground measurements. Furthermore, taking gas-particle partitioning and oxidation of SVOCs into account is found to result in a major improvement of the agreement of simulations and satellite measurements of aerosol optical depth, as well as in considerable changes in predicted aerosol composition and top-down BB aerosol emission estimates derived from AOD measurements.
Highlights
Carbonaceous aerosol originating from open biomass burning (BB) plays a major role in the atmosphere by affecting both climate processes and air quality (Andreae and Merlet, 2001; Langmann et al, 2009)
We used the volatility basis set (VBS) framework for organic aerosol (OA) modeling to simulate the mesoscale evolution of aerosol from open biomass burning for the case of the mega-fire event that occurred in Russia in the summer of 2010
We modified the VBS scheme in the CHIMERE chemistry transport model by using data from laboratory experiments aimed at studying gas-particle partitioning and oxidation processes in the mixtures of gases and aerosols emitted from biomass burning (BB)
Summary
Carbonaceous aerosol originating from open biomass burning (BB) plays a major role in the atmosphere by affecting both climate processes and air quality (Andreae and Merlet, 2001; Langmann et al, 2009). Konovalov et al.: Mesoscale evolution of biomass burning aerosol. Episodes of a major impact of aerosol emissions from fires on regional air quality have been reported worldwide (e.g., Heil and Goldammer, 2001; Andreae et al, 2002; Sinha et al, 2003; Bertschi and Jaffe, 2005; Konovalov et al, 2011; Strand et al, 2012; Andreae et al, 2012; Engling et al, 2014). The physical and chemical properties of BB aerosol and its sources and evolution have to be adequately represented in atmospheric numerical models aimed at analyzing and predicting climate change and air pollution phenomena (e.g., Kiehl et al, 2007; Goodrick et al, 2012)
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