Emission ratios of trace gases and particles for Siberian forest fires on the basis of mobile ground observations

Abstract

Abstract. Boreal forest fires are currently recognized as a significant factor in climate change and air quality problems. Although emissions of biomass burning products are widely measured in many regions, there is still lack of information on the composition of wildfire emissions in Siberia, a region known for its severe wildfire activity. Emission ratios (ERs) are important characteristics of wildfire emissions as they may be used to calculate the mass of species emitted into the atmosphere due to combustion of a known mass of biomass fuel. We analyze observations of carbon dioxide (CO 2 ), carbon monoxide (CO), methane (CH 4 ), total nonmethane hydrocarbons (NMHCs), nitrogen oxides NO x (= NO + NO 2 ), particulate matter (PM 3 ), and black carbon (BC) within two forest fire plume transects made by the moving railway observatory during TRanscontinental Observations Into the Chemistry of the Atmosphere (TROICA) expeditions. Slopes in linear regressions of excess levels of the pollutants are used to obtain ER CO / CO 2 = 10-15 %, ER CH 4 / CO = 8-10 %, ER NMHC / CO = 0.11-0.21 % ppmC ppmC −1 , ER NO x / CO = 1.5-3.0 ppb ppm −1 , ER PM 3 / CO = 320-385 ng m −3 µg m −3 −1 , and ER BC / CO = 6.1-6.3 µg m −3 ppm −1 , which fall within the range of uncertainty of the previous estimates, being at the higher edge for ER CH 4 / CO , ER NMHC / CO , and ER PM 3 / CO and at the lower edge for ER NO x / CO . The relative uncertainties comprise 5-15 % of the estimated ER CH 4 / CO , ER NMHC / CO , and ER PM / CO and 10-20 % of ER NO x / CO , ER CO / CO 2 , and ER BC / CO . The uncertainties are lower than in many other similar studies and associated mainly with natural variability of wildfire emissions.

Boreal forest fire CO and CH<sub>4</sub> emission factors derived from tower observations in Alaska during the extreme fire season of 2015

“…Analysis of these data indicates that smoldering processes may have a higher contribution to total wildfire emissions from North American boreal forests than previous estimates derived from aircraft sampling. To quantify the spatial and temporal variability of individual fires and their influence on CO, CH 4 , and CO 2 at the CRV tower, we coupled a fire emissions inventory, the Alaska Fire Emissions Database (AKFED) (Veraverbeke et al, 2015), with an atmospheric transport model, the Polar Weather Research and Forecasting Stochastic Time Integrated Lagrangian Transport (PWRF-STILT) model (Henderson et al, 2015). This modeling analysis indicated that the number of 2015 wildfires sampled in our study is comparable to the total number of North American boreal forest fires sampled in past work.…”

“…We coupled a fire emission model, the Alaskan Fire Emissions Database (AKFED) (Veraverbeke et al, 2015), with an atmospheric transport model, the Polar Weather Research and Forecasting Stochastic Time Integrated Lagrangian Transport model (PWRF-STILT) (Henderson et al, 2015), to estimate fire contributions to trace gas variability at the CRV tower, following Wiggins et al (2016). For this application, STILT (Lin et al, 2007) was used to estimate the adjoint of PWRF (Skamarock et al, 2005;Chang et al, 2014;Henderson et al, 2015) during the summer of 2015 at the location of the CRV tower to generate surface influence functions that relate surface ecosystem fluxes from Alaska to trace mole fractions at CRV.…”

“…The daily burned area in AKFED was mapped using thermal imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) within fire perimeters from the Alaska Large Fire Database. Both above-and belowground carbon consumption were modeled as a function of elevation, day of burning, pre-fire tree cover, and difference normalized burn ratio (dNBR) measurements derived from 500 m MODIS surface reflectance bands (Veraverbeke et al, 2015). AK-FED predicted carbon emissions from fires with a temporal resolution of 1 d and a spatial resolution of 450 m. We regridded AKFED to the same spatial resolution as the atmospheric transport model (0.5 • ) for the model coupling.…”

“…This was achieved by calculating the total CO contribution from each individual 0.5 • grid cell from the AKFED × PWRF-STILT combined model and utilizing the fire perimeters from the Alaska Large Fire Database (data provided by the Bureau of Land Management (BLM) Alaska Fire Service, on behalf of the Alaska Wildland Fire Coordinating Group (AWFCG) and Alaska Interagency Coordination Center (AICC)) to identify the location of individual fires. AKFED uses the same fire perimeter database for burned area and carbon emissions estimates (Veraverbeke et al, 2015). We determined an individual fire's contribution to CO at the CRV tower by setting all emissions in AKFED for a particular grid cell to zero and rerunning the model cou-E. B. Wiggins et al: Boreal forest fire CO and CH 4 emission factors pling with PWRF-STILT.…”

DETECTION Of ATMOSPHERIC POLLUTION SOURCES BY USING CROSS-PLUME SCANNING METHOD AND MOBILE RAILwAY LABORATORY

“…The modern TROICA mobile railroad laboratory, which was manufactured in 2004 after a special design, is equipped with high-precision instruments intended for monitoring the gas and aerosol composition of the atmosphere and the radiative and meteorological characteristics and also for monitoring the soil, water, and vegetation pollution. At present, the laboratory is able of continuous real-time monitoring the concentrations of ozone (O 3 ), nitrogen oxides (NO and NO 2 ), carbon oxides (CO and CO 2 ), methane (CH 4 ) and a sum of non-methane hydrocarbons (NMHC), sulfur dioxide (SO 2 ), ammonia (NH 3 ), about 30 volatile organic compounds (VOCs), and radon ( 222 Rn) and its decay products, the mass and number concentrations of aerosol particles (including soot) in the size range from 2 nm to 15 µm, and the entire spectrum of meteorological parameters and solar-radiation characteristics with a high temporal resolution (from 10 s to 20 min), see (Berezina et al 2013), , (Vasileva et al 2017). As a result of cooperation between a number of Russian and world scientific centers, a series of 15 international experiments on observations of the state of the atmosphere over vast Russian regions, from Moscow to Vladivostok and from Murmansk to Kislovodsk, was performed.…”