41. Comparing black-carbon- and aerosol-absorption-measuring instruments – a new system using lab-generated soot coated with controlled amounts of secondary organic matterDaniel M. Kalbermatter, Griša Močnik, Luka Drinovec, Bradley Visser, Jannis Röhrbein, Matthias Oscity, Ernest Weingartner, Antti-Pekka Hyvärinen, Konstantina Vasilatou, 2022, original scientific article Abstract: We report on an inter-comparison of black-carbon- and aerosol-absorption-measuring instruments with laboratory-generated soot particles coated with controlled amounts of secondary organic matter (SOM). The aerosol generation setup consisted of a miniCAST 5201 Type BC burner for the generation of soot particles and a new automated oxidation flow reactor based on the micro smog chamber (MSC) for the generation of SOM from the ozonolysis of α-pinene. A series of test aerosols was generated with elemental to total carbon (EC TC) mass fraction ranging from about 90 % down to 10 % and single-scattering albedo (SSA at 637 nm) from almost 0 to about 0.7. A dual-spot Aethalometer AE33, a photoacoustic extinctiometer (PAX, 870 nm), a multi-angle absorption photometer (MAAP), a prototype photoacoustic instrument, and two prototype photo-thermal interferometers (PTAAM-2λ and MSPTI) were exposed to the test aerosols in parallel. Significant deviations in the response of the instruments were observed depending on the amount of secondary organic coating. We believe that the setup and methodology described in this study can easily be standardised and provide a straightforward and reproducible procedure for the inter-comparison and characterisation of both filter-based and in situ black-carbon-measuring (BC-measuring) instruments based on realistic test aerosols.
Keywords: black carbon, aerosol absorption, secondary organic aerosol, coating
Published in RUNG: 01.02.2022; Views: 1872; Downloads: 49
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42. Experimental dataset - A dual-wavelength photothermal aerosol absorption monitor: design, calibration and performanceLuka Drinovec, Uroš Jagodič, Luka Pirker, Miha Škarabot, Mario Kurtjak, Kristijan Vidović, Luca Ferrero, Bradley Visser, Jannis Röhrbein, Ernest Weingartner, Daniel Kalbermatter, Konstantina Vasilatou, Tobias Bühlmann, Celine Pascale, Thomas Müller, Alfred Wiedensohler, Griša Močnik, complete scientific database of research data Keywords: photothermal interferometer, aerosol light absorption coefficient
Published in RUNG: 14.01.2022; Views: 1990; Downloads: 28
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43. Contribution of coal combustion to black carbon : coupling tracers with the aethalometer modelC. Blanco-Alegre, Paulo Fialho, A. I. Calvo, A. Castro, E. Coz, F. Oduber, A. S. H. Prevot, Griša Močnik, C. Alves, F. Giardi, G. Pazzi, R. Fraile, 2022, original scientific article Keywords: absorption coefficient, coal-mining, equivalent black carbon, meteorological variables, seasonal pattern
Published in RUNG: 03.01.2022; Views: 1801; Downloads: 0
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44. Detection of mineral dust concentration in Mediterranean and Central Europe by measuring optical absorption of dust particlesMatic Ivančič, Irena Ježek, Martin Rigler, Asta Gregorič, Balint Alfoldy, Luka Drinovec, JEAN SCIARE, Michael Pikridas, FLORIN UNGA, Andrés Alastuey, Marco Pandolfi, Jesús Yus-Díez, Griša Močnik, 2020, unpublished conference contribution Keywords: mineral dust, optical absorption, virtual impactor
Published in RUNG: 22.11.2021; Views: 2151; Downloads: 0
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45. Bioaerosol partitioning between the interstitial and condensed phase in mixed-phase clouds : lecture NOSA Symposium 2021, March 16th 2021, onlineTina Šantl Temkiv, Miha Živec, Mojca Benčina, Samo Stanič, Griša Močnik, 2021, unpublished conference contribution Keywords: bioaerosol, aerosol, mixed-phase clouds, LIDAR
Published in RUNG: 22.11.2021; Views: 1983; Downloads: 45
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46. Determination of high-time resolution mineral dust concentration in real-time by optical absorption measurementsMatic Ivančič, Irena Ježek, Martin Rigler, Asta Gregorič, Bálint Alföldy, Rok Podlipec, Luka Drinovec, Griša Močnik, 2021, published scientific conference contribution abstract Keywords: mineral dust, concentration, aerosols, air quality
Published in RUNG: 17.11.2021; Views: 1880; Downloads: 13
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47. The determination of source-separated black carbon emission rates using radon as a tracer of atmospheric dynamicsAsta Gregorič, Luka Drinovec, Janja Vaupotič, Irena Ježek, Matic Ivančič, Janja Turšič, Griša Močnik, 2021, published scientific conference contribution abstract Keywords: black carbon, emission rate, aethalometer, radon
Published in RUNG: 17.11.2021; Views: 2014; Downloads: 42
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48. Bora flow characteristics in a complex valley environmentMarija Bervida, Samo Stanič, Griša Močnik, Longlong Wang, Klemen Bergant, Xiaoquan Song, 2021, original scientific article Abstract: This paper complements the existing studies of Bora flow properties in the Vipava valley with the study of Bora turbulence in a lower region of the troposphere. The turbulence characteristics of Bora flow were derived from high resolution Doppler wind lidar measurements during eight Bora wind episodes that occurred in November and December 2019. Based on the vertical profiles of wind velocity, from 80 to 180 m above the valley floor, the turbulence intensity related to all three spatial directions and the along-wind integral length scales related to three velocity components were evaluated and compared to the approximations given in international standards. The resulting turbulence characteristics of Bora flow in a deep mountain valley exhibited interesting behaviour, differing from the one expected and suggested by standards. The intensity of turbulence during Bora episodes was found to be quite strong, especially regarding the expected values for that particular category of terrain. The specific relationship between along-wind, lateral and vertical intensity was evaluated as well. The scales of turbulence in the along-wind direction were found to vary widely between different Bora episodes and were rather different from the approximations given by standards, with the most significant deviations observed for the along-wind length scale of the vertical velocity component. Finally, the periodicity of flow structures above the valley was assessed, yielding a wide range of possible periods between 1 and 10 min, thus confirming some of the previous observations from the studies of Bora in the Vipava valley.
Keywords: doppler wind lidar, Bora wind, turbulence intensity, complex terrain, turbulence integral length scale
Published in RUNG: 05.11.2021; Views: 2210; Downloads: 42
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49. Characterization of non-refractory (NR) PM[sub]1 and source apportionment of organic aerosol in Kraków, PolandAnna Tobler, Alicja Skiba, Francesco Canonaco, Griša Močnik, Pragati Rai, Gang Chen, Jakub Bartyzel, Miroslaw Zimnoch, Katarzyna Styszko, Jaroslaw Nęcki, 2021, original scientific article Abstract: Kraków is routinely affected by very high air pollution levels, especially during the winter months. Although a lot of effort has been made to characterize ambient aerosol, there is a lack of online and long-term measurements of non-refractory aerosol. Our measurements at the AGH University of Science and Technology provide the online long-term chemical composition of ambient submicron particulate matter (PM1) between January 2018 and April 2019. Here we report the chemical characterization of non-refractory submicron aerosol and source apportionment of the organic fraction by positive matrix factorization (PMF). In contrast to other long-term source apportionment studies, we let a small PMF window roll over the dataset instead of performing PMF over the full dataset or on separate seasons. In this way, the seasonal variation in the source profiles can be captured. The uncertainties in the PMF solutions are addressed by the bootstrap resampling strategy and the random a-value approach for constrained factors.
We observe clear seasonal patterns in the concentration and composition of PM1, with high concentrations during the winter months and lower concentrations during the summer months. Organics are the dominant species throughout the campaign. Five organic aerosol (OA) factors are resolved, of which three are of a primary nature (hydrocarbon-like OA (HOA), biomass burning OA (BBOA) and coal combustion OA (CCOA)) and two are of a secondary nature (more oxidized oxygenated OA (MO-OOA) and less oxidized oxygenated OA (LO-OOA)). While HOA contributes on average 8.6 % ± 2.3 % throughout the campaign, the solid-fuel-combustion-related BBOA and CCOA show a clear seasonal trend with average contributions of 10.4 % ± 2.7 % and 14.1 %, ±2.1 %, respectively. Not only BBOA but also CCOA is associated with residential heating because of the pronounced yearly cycle where the highest contributions are observed during wintertime. Throughout the campaign, the OOA can be separated into MO-OOA and LO-OOA with average contributions of 38.4 % ± 8.4 % and 28.5 % ± 11.2 %, respectively.
Keywords: air pollution, PM1, organic aerosol, black carbon, source apportionment, PMF
Published in RUNG: 08.10.2021; Views: 2072; Downloads: 0
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50. Determination of the multiple-scattering correction factor and its cross-sensitivity to scattering and wavelength dependence for different AE33 Aethalometer filter tapes : a multi-instrumental approachJesús Yus-Díez, Vera Bernardoni, Griša Močnik, Andrés Alastuey, Davide Ciniglia, Matic Ivančič, Xavier Querol, Noemí Perez, Cristina Reche, Martin Rigler, Roberta Vecchi, Sara Valentini, Marco Pandolfi, 2021, original scientific article Abstract: Providing reliable observations of aerosol particles' absorption properties at spatial and temporal resolutions suited to climate models is of utter importance to better understand the effects that atmospheric particles have on climate. Nowadays, one of the instruments most widely used in international monitoring networks for in situ surface measurements of light absorption properties of atmospheric aerosol particles is the multi-wavelength dual-spot Aethalometer, AE33. The AE33 derives the absorption coefficients of aerosol particles at seven different wavelengths from the measurements of the optical attenuation of light through a filter where particles are continuously collected. An accurate determination of the absorption coefficients from the AE33 instrument relies on the quantification of the non-linear processes related to the sample collection on the filter. The multiple-scattering correction factor (C), which depends on the filter tape used and on the optical properties of the collected particles, is the parameter with both the greatest uncertainty and the greatest impact on the absorption coefficients derived from the AE33 measurements.
Here we present an in-depth analysis of the AE33 multiple-scattering correction factor C and its wavelength dependence for two different and widely used filter tapes, namely the old, and most referenced, TFE-coated glass, or M8020, filter tape and the currently, and most widely used, M8060 filter tape. For performing this analysis, we compared the attenuation measurements from AE33 with the absorption coefficients measured with different filter-based techniques. On-line co-located multi-angle absorption photometer (MAAP) measurements and off-line PP_UniMI polar photometer measurements were employed as reference absorption measurements for this work. To this aim, we used data from three different measurement stations located in the north-east of Spain, namely an urban background station (Barcelona, BCN), a regional background station (Montseny, MSY) and a mountaintop station (Montsec d'Ares, MSA). The median C values (at 637 nm) measured at the three stations ranged between 2.29 (at BCN and MSY, lowest 5th percentile of 1.97 and highest 95th percentile of 2.68) and 2.51 (at MSA, lowest 5th percentile of 2.06 and highest 95th percentile of 3.06). The analysis of the cross-sensitivity to scattering, for the two filter tapes considered here, revealed a large increase in the C factor when the single-scattering albedo (SSA) of the collected particles was above a given threshold, up to a 3-fold increase above the average C values. The SSA threshold appeared to be site dependent and ranged between 0.90 to 0.95 for the stations considered in the study. The results of the cross-sensitivity to scattering displayed a fitted constant multiple-scattering parameter, Cf, of 2.21 and 1.96, and a cross-sensitivity factor, ms, of 1.8 % and 3.4 % for the MSY and MSA stations, respectively, for the TFE-coated glass filter tape. For the M8060 filter tape, Cf values of 2.50, 1.96 and 1.82 and ms values of 1.6 %, 3.0 % and 4.9 % for the BCN, MSY and MSA stations, respectively, were obtained. SSA variations also influenced the spectral dependence of C, which showed an increase with wavelength when SSA was above the site-dependent threshold. Below the SSA threshold, no statistically significant dependence of C on the wavelength was observed. For the measurement stations considered here, the wavelength dependence of C was to some extent driven by the presence of dust particles during Saharan dust outbreaks that had the potential to increase the SSA above the average values. At the mountaintop station, an omission of the wavelength dependence of the C factor led to an underestimation of the absorption Ångström exponent (AAE) by up to 12 %. Differences in the absorption coefficient determined from AE33 measurements at BCN, MSY and MSA of around 35 %–40 % can be expected when using the site-dependent experimentally obtained C value instead of the nominal C value. Due to the fundamental role that the SSA of the particles collected on the filter tape has in the multiple-scattering parameter C, we present a methodology that allows the recognition of the conditions upon which the use of a constant and wavelength-independent C is feasible.
Keywords: black carbon, aerosol absorption, filter photometer, artifact
Published in RUNG: 01.10.2021; Views: 2114; Downloads: 0
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