The new TC-BC method and online instrument for the measurement of carbonaceous aerosols

Rigler, Martin; Drinovec, Luka; Lavrič, Gašper; Vlachou, Athanasia; Prévôt, Andrê S. H.; Jaffrezo, Jeań Luc; Stavroulas, Iasonas; Sciare, Jean; Burger, Judita; Kranjc, Irena; Turšič, Janja; Hansen, A. D. A.; Močnik, Griša

doi:10.5194/amt-2019-376

Cited by 1 publication

(1 citation statement)

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“…Moreover, EC measurements are used to calibrate the MAC value that aethalometers use to derive BC mass from the absorption coefficient. Even though BC is equated to EC for the purpose of calibration, EC to BC ratio measurements in BB literature are highly variable ranging from 0.3 to 1.6 and appear to be strongly related to the aerosol type, the degree of atmospheric processing (Rigler et al, 2019;Salako et al, 2012) and the MCE of the fire (Aurell et al, 2017). Using the manufacturer-defined MAC of 7.8 m 2 g -1 , BC concentrations and the difference compared to the EC concentrations were 223 μg m -3 (-71%), 16 μg m -3 (-56%) and 57 μg m -3 (+20%), for the experiments at FLARE, TROPOS and KNP, respectively.…”

Section: Ebc Mass Concentration Measurementsmentioning

confidence: 99%

An Unmanned Aerial System (UAS) based methodology for measuring biomass burning emission factors

Vernooij

Winiger

Wooster

et al. 2022

Preprint

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Abstract. Biomass burning (BB) emits large quantities of greenhouse gases (GHG) and aerosols that impact climate and adversely affect human health. Although much research has focused on quantifying BB emissions on regional to global scales, field measurements of BB emission factors (EFs) are sparse, clustered and indicate high spatio-temporal variability. EFs are generally calculated from ground- or aeroplane measurements with respective potential biases towards smouldering or flaming combustion products. Unmanned aerial systems (UAS) have the potential to measure BB EFs in fresh smoke, targeting different parts of the plume at relatively low cost. We propose a light-weight UAS-based method to measure EFs for carbon monoxide (CO), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), as well as PM2.5 (TSI Sidepak AM520) and equivalent black carbon (eBC, microAeth AE51) using a combination of a sampling system with Tedlar bags which can be analysed on the ground and airborne aerosol sensors. In this study, we address the main uncertainties associated with this approach (1) the degree to which taking a limited number of samples is representative for the integral smoke plume and including (2) the reliability of the lightweight aerosol sensors. This was done for prescribed burning experiments in the Kruger national park, South Africa where we compared fire-averaged EF from UAS-sampled bags for savanna fires to integrated EFs from co-located mast measurements. Both measurements matched reasonably well with linear R2 ranging from 0.81 to 0.94. Both aerosol sensors are not factory calibrated for BB particles and therefore require additional calibration. In a series of smoke chamber experiments, we compared the lightweight sensors to high-fidelity equipment to empirically determine specific calibration factors (CF) for measuring BB particles. For the PM mass concentration from a TSI Sidepak AM520, we found an optimal CF of 0.27, using a scanning mobility particle sizer and gravimetric reference methods, albeit that the CF varied for different vegetation fuel types. Measurements of eBC from the Aethlabs AE51 aethalometer agreed well with the multi-wavelength aethalometer (AE33) (linear R2 of 0.95 at λ = 880 nm) and the wavelength corrected Multi-Angle Absorption Photometer (MAAP, R2 0.83 measuring at λ = 637 nm). However, the high variability in observed BB mass absorption cross-section (MAC) values (5.2 ± 5.1 m2 g-1) suggested re-calibration may be required for individual fires. Overall, our results indicate that the proposed UAS setup can obtain representative BB EFs for individual savanna fires if proper correction factors are applied and operating limitations are well understood.

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Section: Ebc Mass Concentration Measurementsmentioning

confidence: 99%