Estimation of black carbon emissions from Siberian fires using satellite observations of absorption and extinction optical depths

Abstract

Abstract. Black carbon (BC) emissions from open biomass burning (BB) are known to have a considerable impact on the radiative budget of the atmosphere at both global and regional scales; however, these emissions are poorly constrained in models by atmospheric observations, especially in remote regions. Here, we investigate the feasibility of constraining BC emissions from BB using satellite observations of the aerosol absorption optical depth (AAOD) and the aerosol extinction optical depth (AOD) retrieved from OMI (Ozone Monitoring Instrument) and MODIS (Moderate Resolution Imaging Spectroradiometer) measurements, respectively. We consider the case of Siberian BB BC emissions, which have the strong potential to impact the Arctic climate system. Using aerosol remote sensing data collected at Siberian sites of the AErosol RObotic NETwork (AERONET) along with the results of the fourth Fire Lab at Missoula Experiment (FLAME-4), we establish an empirical parameterization relating the ratio of the elemental carbon (EC) and organic carbon (OC) contents in BB aerosol to the ratio of AAOD and AOD at the wavelengths of the satellite observations. Applying this parameterization to the BC and OC column amounts simulated using the CHIMERE chemistry transport model, we optimize the parameters of the BB emission model based on MODIS measurements of the fire radiative power (FRP); we then obtain top-down optimized estimates of the total monthly BB BC amounts emitted from intense Siberian fires that occurred from May to September 2012. The top-down estimates are compared to the corresponding values obtained using the Global Fire Emissions Database (GFED4) and the Fire Emission Inventory–northern Eurasia (FEI-NE). Our simulations using the optimized BB aerosol emissions are verified against AAOD and AOD data that were withheld from the estimation procedure. The simulations are further evaluated against in situ EC and OC measurements at the Zotino Tall Tower Observatory (ZOTTO) and also against aircraft aerosol measurement data collected in the framework of the Airborne Extensive Regional Observations in SIBeria (YAK-AEROSIB) experiments. We conclude that our BC and OC emission estimates, considered with their confidence intervals, are consistent with the ensemble of the measurement data analyzed in this study. Siberian fires are found to emit 0.41±0.14 Tg of BC over the whole 5-month period considered; this estimate is a factor of 2 larger and a factor of 1.5 smaller than the corresponding estimates based on the GFED4 (0.20 Tg) and FEI-NE (0.61 Tg) data, respectively. Our estimates of monthly BC emissions are also found to be larger than the BC amounts calculated using the GFED4 data and smaller than those calculated using the FEI-NE data for any of the 5 months. Particularly large positive differences of our monthly BC emission estimates with respect to the GFED4 data are found in May and September. This finding indicates that the GFED4 database is likely to strongly underestimate BC emissions from agricultural burns and grass fires in Siberia. All of these differences have important implications for climate change in the Arctic, as it is found that about a quarter of the huge BB BC mass emitted in Siberia during the fire season of 2012 was transported across the polar circle into the Arctic. Overall, the results of our analysis indicate that a combination of the available satellite observations of AAOD and AOD can provide the necessary constraints on BB BC emissions.

Nonlinear behavior of organic aerosol in biomass burning plumes: a microphysical model analysis

“…The emission factors from Andreae (2019) for the boreal forest were used to specify initial concentrations of POA precursors as a function of the initial concentration of BB OA. Note that the original SOA formation scheme from the CHIMERE model was earlier used in the simulations of evolution of BB aerosol from Russian fires (Konovalov et al, 2015(Konovalov et al, , 2017(Konovalov et al, , 2018 and was found to produce rather negligible amounts of SOA in BB plumes.…”

“…Representing the processes involving SVOCs and IVOCs within the VBS framework has been shown to allow improving the performance of simulations of OA from vegetation fires with respect to simulations using the "conventional" OA modeling framework, in which these processes are basically disregarded and only specific volatile organic compounds (VOCs) are considered to be precursors of SOA (Hodzic et al, 2010;Shrivastava et al, 2015;Konovalov et al, 2015Konovalov et al, , 2017. Based on simulations using the VBS method, it has also been argued (Konovalov et al, 2015(Konovalov et al, , 2017 that disregard for the BB OA aging processes might be one of the main reasons for a strong underestimation of aerosol optical depth in BB plumes by chemistry-transport models using the conventional representation of OA evolution (e.g., Tosca et al, 2013;Konovalov et al, 2014Konovalov et al, , 2018Reddington et al, 2016;Petrenko et al, 2017). It should be noted, however, that the representation of the BB OA evolution within the VBS framework in chemistry-transport models is still associated with major uncertainties: while a variety of VBS schemes of different complexities have been suggested for BB OA modeling (e.g., Grieshop et al, 2009;Koo et al, 2014;Shrivastava et al, 2015;Ciarelli et al, 2017a;Tsimpidi et al, 2018), any of these schemes has only partially been constrained by laboratory or ambient measurements.…”

“…The scheme "C17" has been described and evaluated by Ciarelli et al (2017a, b). It is a relatively simple scheme which has been referred to as a hybrid 1.5-dimensional VBS (1.5-D-VBS) and is based on a similar scheme proposed by Koo et al (2014). The idea behind this scheme is to characterize sources, volatilities, chemical transformation, and oxidation state of a complex mixture of SVOCs by considering several surrogate species which are given average molecular compositions and molecular weights.…”

Fossil fuel combustion and biomass burning sources of global black carbon from GEOS-Chem simulation and carbon isotope measurements

“…This is a state-of-the-art global model for simulating global distribution of BC (Wang et al, 2011;Qi et al, 2017a, c). We use 15 size bins ranging from 3 nm to 10 µm, with tracers for sulfate, sea salt, organic aerosols, BC and dust (Pierce et al, 2007;Lee et al, 2009;D'Andrea et al, 2013;Kodros and Peirce, 2017). Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA2), meteorological data sets are used to drive model simulation at 4 • latitude × 5 • longitude horizontal resolution and 47 vertical layers from the surface to 0.01 hPa.…”

How Has the Hazard to Humans of Microorganisms Found in Atmospheric Aerosol in the South of Western Siberia Changed over 10 Years?

“…Western Siberia is a region in which global climatic changes are clearly manifested: permafrost thawing, decrease in snow cover time, temperature increase, powerful greenhouse gas emissions [35][36][37][38][39][40][41][42][43][44][45]. At the same time, changes in the state of health of the population of the region caused by these climatic changes are poorly studied (see, for example, [37,46,47]).…”