51. Sarajevo Canton Winter Field Campaign 2018 : particulate air pollution in a global hotspotKatja Džepina, Vaios Moschos, Anna Tobler, Francesco Canonaco, Deepika Bhattu, Roberto Casotto, Athanasia Vlachou, Jasna Huremović, Sabina Žero, Griša Močnik, 2020, published scientific conference contribution abstract Abstract: Nowadays, urban centres in countries of the Western Balkan region (including Bosnia and Herzegovina (B&H)) are experiencing some of the poorest European and global air quality due to the extensive use of solid fuels (e.g., wood, coal) and old vehicle fleet. Western Balkan countries lack state-of-the-art atmospheric sciences research despite high levels of ambient pollution, which makes the efforts to understand the mechanisms of their air pollution imperative. The city of Sarajevo, the capital of B&H, is situated in a basin surrounded by mountains. Particularly during the winter months, topography and meteorology cause significant pollution episodes.
The Sarajevo Canton Winter Field Campaign 2018 (SAFICA) took place from Dec 04, 2017 to Mar 15, 2018 with on-line aerosol measurements and collection of daily, continuous filter PM10 samples for off-line laboratory analyses. SAFICA aimed to give the first detailed characterization of the Western Balkans aerosol composition including organic aerosol (OA) to elucidate aerosol emission sources and atmospheric processing and to estimate the adverse health effects. PM10 samples (ntotal=180) were collected at four sites in the Sarajevo Canton: a) Bjelave and b) Pofalići (urban background); c) Otoka (urban); d) Ivan Sedlo (remote). The urban sites were distributed along the city basin to study the pollutants’ urban evolution and the remote site was chosen to compare urban to background air masses.
SAFICA PM10 samples underwent different off-line laboratory chemical analyses: 1) Bulk chemical composition of the total filter-collected water-soluble inorganic and OA by a high-resolution Aerodyne Aerosol Mass Spectrometer (AMS). The measured AMS OA spectra were further analysed by Positive Matrix Factorization (PMF) using the graphical user interface SoFi (Source Finder) to separate OA into subtypes characteristic for OA sources and atmospheric processes. 2) Organic and elemental carbon (OC/EC), water-soluble organic carbon, polycyclic aromatic hydrocarbons, levoglucosan, and 14C content of total carbon to evaluate OA chemical composition. 3) Major inorganic anions and cations to evaluate aerosol inorganic species. 4) Metal content in aerosol determined by two analytical techniques (AAS and ICP-MS). SAFICA on-line measurements of black carbon (Aethalometer) and the particle number concentration (Condensation Particle Counter and Optical Particle Sizer) enabled the insights into the daily evolution of primary pollutants and an assessment of aerosol size and number distribution.
The combined SAFICA results for on- and off-line measurements will be presented. Our results show that the carbon-containing species make ~2/3 of PM10 mass and the majority are oxygenated, water-soluble OA species with an average OM/OC = 1.9 (Fig.1). Urban air pollution crises in the Western Balkan will be put in the context of local, regional and global air quality. Finally, we will present the scientific questions opened by SAFICA, including the advantages and limitations of SAFICA data set, and give the recommendations for future studies.
Keywords: Sarajevo, urban air pollution, PM10, PM2.5
Published in RUNG: 26.05.2021; Views: 2480; Downloads: 20
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52. The determination of highly time-resolved and source-separated black carbon emission rates using radon as a tracer of atmospheric dynamicsAsta Gregorič, Luka Drinovec, Irena Ježek, Janja Vaupotič, Matevž Lenarčič, Domen Grauf, Longlong Wang, Maruška Mole, Samo Stanič, Griša Močnik, 2020, original scientific article Keywords: black carbon, radon, air pollution, biomass burning, Aethalometer
Published in RUNG: 10.05.2021; Views: 2346; Downloads: 0
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53. Intercomparison and characterization of 23 Aethalometers under laboratory and ambient air conditions: : procedures and unit-to-unit variabilitiesAndrea Cuesta-Mosquera, Griša Močnik, Luka Drinovec, Thomas Müller, Sascha Pfeifer, Maria Cruz Minguillon, Björn Briel, Paul Buckley, Vadimas Dudoitis, Javier Fernández-García, 2021, original scientific article Abstract: Aerosolized black carbon is monitored worldwide to quantify its impact on air quality and climate. Given its importance, measurements of black carbon mass concentrations must be conducted with instruments operating in quality-checked and ensured conditions to generate data which are reliable and comparable temporally and geographically.
In this study, we report the results from the largest characterization and intercomparison of filter-based absorption photometers, the Aethalometer model AE33, belonging to several European monitoring networks. Under controlled laboratory conditions, a total of 23 instruments measured mass concentrations of black carbon from three well-characterized aerosol sources: synthetic soot, nigrosin particles, and ambient air from the urban background of Leipzig, Germany. The objective was to investigate the individual performance of the instruments and their comparability; we analyzed the response of the instruments to the different aerosol sources and the impact caused by the use of obsolete filter materials and the application of maintenance activities.
Differences in the instrument-to-instrument variabilities from equivalent black carbon (eBC) concentrations reported at 880 nm were determined before maintenance activities (for soot measurements, average deviation from total least square regression was −2.0 % and the range −16 % to 7 %; for nigrosin measurements, average deviation was 0.4 % and the range −15 % to 17 %), and after they were carried out (for soot measurements, average deviation was −1.0 % and the range −14 % to 8 %; for nigrosin measurements, the average deviation was 0.5 % and the range −12 % to 15 %). The deviations are in most of the cases explained by the type of filter material employed by the instruments, the total particle load on the filter, and the flow calibration.
The results of this intercomparison activity show that relatively small unit-to-unit variability of AE33-based particle light absorbing measurements is possible with well-maintained instruments. It is crucial to follow the guidelines for maintenance activities and the use of the proper filter tape in the AE33 to ensure high quality and comparable black carbon (BC) measurements among international observational networks.
Keywords: black carbon, aerosol, absorption, filter absorption photometer, aethaloemter
Published in RUNG: 03.05.2021; Views: 1993; Downloads: 0
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54. Determination of Aethalometer multiple-scattering enhancement parameters and impact on source apportionment during the winter 2017/18 EMEP/ACTRIS/COLOSSAL campaign in MilanVera Bernardoni, Luca Ferrero, Ezio Bolzacchini, Alice Corina Forello, Asta Gregorič, Dario Massabo, Griša Močnik, Paolo Prati, Martin Rigler, Luca Santagostini, 2021, original scientific article Abstract: In the frame of the EMEP/ACTRIS/COLOSSAL campaign in Milan during winter 2018, equivalent black carbon measurements using the Aethalometer 31 (AE31), the Aethalometer 33 (AE33), and a Multi-Angle Absorption Photometer (MAAP) were carried out together with levoglucosan analyses on 12 h resolved PM2.5 samples collected in parallel.
From AE31 and AE33 data, the loading-corrected aerosol attenuation coefficients (bATN) were calculated at seven wavelengths (λ, where λ values are 370, 470, 520, 590, 660, 880, and 950 nm). The aerosol absorption coefficient at 637 nm (babs_MAAP) was determined by MAAP measurements. Furthermore, babs was also measured at four wavelengths (405, 532, 635, 780 nm) on the 12 h resolved PM2.5 samples by a polar photometer (PP_UniMI).
After comparing PP_UniMI and MAAP results, we exploited PP_UniMI data to evaluate the filter multiple-scattering enhancement parameter at different wavelengths for AE31 and AE33. We obtained instrument- and wavelength-dependent multiple-scattering enhancement parameters by linear regression of the Aethalometer bATN against the babs measured by PP_UniMI. We found significant dependence of the multiple-scattering enhancement parameter on filter material, hence on the instrument, with a difference of up to 30 % between the AE31 and the AE33 tapes. The wavelength dependence and day–night variations were small – the difference between the smallest and largest value was up to 6 %.
Data from the different instruments were used as input to the so-called “Aethalometer model” for optical source apportionment, and instrument dependence of the results was investigated. Inconsistencies among the source apportionment were found fixing the AE31 and AE33 multiple-scattering enhancement parameters to their usual values. In contrast, optimised multiple-scattering enhancement parameters led to a 5 % agreement among the approaches.
Also, the component apportionment “MWAA model” (Multi-Wavelength Absorption Analyzer model) was applied to the dataset. It was less sensitive to the instrument and the number of wavelengths, whereas significant differences in the determination of the absorption Ångström exponent for brown carbon were found (up to 22 %).
Keywords: black carbon, filter photometer, Aethalometer, source apportionment
Published in RUNG: 16.04.2021; Views: 2252; Downloads: 0
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56. The impact of cloudiness and cloud type on the atmospheric heating rate of black and brown carbon in the Po ValleyLuca Ferrero, Asta Gregorič, Griša Močnik, Martin Rigler, Sergio Cogliati, Francesca Barnaba, Luca Di Liberto, Gian Paolo Gobbi, Niccolò Losi, Ezio Bolzacchini, 2021, original scientific article Abstract: We experimentally quantified the impact of cloud fraction and cloud type on the heating rate (HR) of black and brown carbon (HRBC and HRBrC). In particular, we examined in more detail the cloud effect on the HR detected in a previous study (Ferrero et al., 2018). High-time-resolution measurements of the aerosol absorption coefficient at multiple wavelengths were coupled with spectral measurements of the direct, diffuse and surface reflected irradiance and with lidar–ceilometer data during a field campaign in Milan, Po Valley (Italy). The experimental set-up allowed for a direct determination of the total HR (and its speciation: HRBC and HRBrC) in all-sky conditions (from clear-sky conditions to cloudy). The highest total HR values were found in the middle of winter (1.43 ± 0.05 K d−1), and the lowest were in spring (0.54 ± 0.02 K d−1). Overall, the HRBrC accounted for 13.7 ± 0.2 % of the total HR, with the BrC being characterized by an absorption Ångström exponent (AAE) of 3.49 ± 0.01. To investigate the role of clouds, sky conditions were classified in terms of cloudiness (fraction of the sky covered by clouds: oktas) and cloud type (stratus, St; cumulus, Cu; stratocumulus, Sc; altostratus, As; altocumulus, Ac; cirrus, Ci; and cirrocumulus–cirrostratus, Cc–Cs). During the campaign, clear-sky conditions were present 23 % of the time, with the remaining time (77 %) being characterized by cloudy conditions. The average cloudiness was 3.58 ± 0.04 oktas (highest in February at 4.56 ± 0.07 oktas and lowest in November at 2.91 ± 0.06 oktas). St clouds were mostly responsible for overcast conditions (7–8 oktas, frequency of 87 % and 96 %); Sc clouds dominated the intermediate cloudiness conditions (5–6 oktas, frequency of 47 % and 66 %); and the transition from Cc–Cs to Sc determined moderate cloudiness (3–4 oktas); finally, low cloudiness (1–2 oktas) was mostly dominated by Ci and Cu (frequency of 59 % and 40 %, respectively).
HR measurements showed a constant decrease with increasing cloudiness of the atmosphere, enabling us to quantify for the first time the bias (in %) of the aerosol HR introduced by the simplified assumption of clear-sky conditions in radiative-transfer model calculations. Our results showed that the HR of light-absorbing aerosol was ∼ 20 %–30 % lower in low cloudiness (1–2 oktas) and up to 80 % lower in completely overcast conditions (i.e. 7–8 oktas) compared to clear-sky ones. This means that, in the simplified assumption of clear-sky conditions, the HR of light-absorbing aerosol can be largely overestimated (by 50 % in low cloudiness, 1–2 oktas, and up to 500 % in completely overcast conditions, 7–8 oktas).
The impact of different cloud types on the HR was also investigated. Cirrus clouds were found to have a modest impact, decreasing the HRBC and HRBrC by −5 % at most. Cumulus clouds decreased the HRBC and HRBrC by −31 ± 12 % and −26 ± 7 %, respectively; cirrocumulus–cirrostratus clouds decreased the HRBC and HRBrC by −60 ± 8 % and −54 ± 4 %, which was comparable to the impact of altocumulus (−60 ± 6 % and −46 ± 4 %). A higher impact on the HRBC and HRBrC suppression was found for stratocumulus (−63 ± 6 % and −58 ± 4 %, respectively) and altostratus (−78 ± 5 % and −73 ± 4 %, respectively). The highest impact was associated with stratus, suppressing the HRBC and HRBrC by −85 ± 5 % and −83 ± 3 %, respectively. The presence of clouds caused a decrease of both the HRBC and HRBrC (normalized to the absorption coefficient of the respective species) of −11.8 ± 1.2 % and −12.6 ± 1.4 % per okta. This study highlights the need to take into account the role of both cloudiness and different cloud types when estimating the HR caused by both BC and BrC and in turn decrease the uncertainties associated with the quantification of their impact on the climate.
Keywords: black carbon, brown carbon, cloud, atmospheric heating rate, climate change
Published in RUNG: 29.03.2021; Views: 2326; Downloads: 0
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57. Elucidating local pollution and site representativeness at the Jungfraujoch, Switzerland through parallel aerosol measurements at an adjacent mountain ridgeNicolas Bukowiecki, Benjamin Brem, Günther Wehrle, Griša Močnik, Stéphane Affolter, Markus Christian Leuenberger, Martine Collaud Coen, Maxime Hervo, Urs Baltensperger, Martin Gysel, 2021, original scientific article Abstract: Many long-term air pollution and climate monitoring stations face the issue of increasing anthropogenic activities in their vicinity. Furthermore, the spatial representativeness of the sites is often not entirely understood especially in mountainous terrain with complex topographic features. This study presents a 5-year comparison of parallel aerosol measurements (total particle number concentration and equivalent black carbon mass concentration) at the Jungfraujoch in the Swiss Alps (JFJ, 3580 m a.s.l.), and an adjacent mountain ridge, the Jungfrau East Ridge (JER, 3705 m a.s.l.), in 1000 m air-line distance to the main site. The parallel aerosol measurements reveal characteristic differences in the diurnal variations between the two sites under certain specific meteorological conditions. Our analysis estimates that on 20-40% of the days local activities at the Jungfraujoch have a clear influence on the measured time series of the total aerosol number concentration and the equivalent black carbon mass concentration. This influence is mainly seen in form of strong isolated spikes rather than by an increase in the on-site background concentration. They can thus be flagged during the data quality assurance process and filtered from those measurement parameters available at high time resolution. Removing the spikes from the original time series results in daily mean values for the total aerosol number concentration and equivalent black carbon mass concentration that are 5-10 % lower compared to the original signals. During nighttime with hardly any local pollution sources that cause spikes this percentage decreases towards 0%. The signal baselines at the Jungfraujoch and Jungfrau East Ridge correlate well during more than 50% of the days.
Keywords: aerosol long-term monitoring, equivalent black carbon, aerosol number concentration, spatial variation
Published in RUNG: 15.03.2021; Views: 1895; Downloads: 71
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58. Real-time characterization and source apportionment of fine particulate matter in the Delhi megacity area during late winterVipul Lalchandan, Varun Kumar, Anna Tobler, M.T. Navaneeth, Suneeti Mishra, J. G. Slowik, Deepika Bhattu, Pragati Rai, Rangu Satish, Dilip Ganguly, Tiwari Tiwari, Neeraj Rastogi, Tiwari Sashi, Griša Močnik, André S. H. Prévôt, Sachchida Tripathi, 2021, original scientific article Abstract: National Capital Region (NCR) encompassing New Delhi is one of the most polluted urban metropolitan areas in the world.
Real-time chemical characterization of fine particulate matter (PM1 and PM2.5) was carried out using three aerosol mass
spectrometers, two aethalometers, and one single particle soot photometer (SP2) at two sites in Delhi (urban) and one site located
~40 km downwind of Delhi, during January-March, 2018. The campaign mean PM2.5 (NR-PM2.5 + BC) concentrations at the two
urban sites were 153.8±109.4 μg.m-3 and 127.8±83.2 μg.m-3, respectively, whereas PM1 (NR-PM1 + BC) was 72.3 ± 44.0 μg.m-3
at the downwind site. PM2.5 particles were composed mostly of organics (43-44)% followed by chloride (14-17)%, ammonium
(9-11)%, nitrate (9%), sulfate (8-10)%, and black carbon (11-16)%, whereas PM1 particles were composed of 47% organics,
13% sulfate as well as ammonium, 11% nitrate as well as chloride, and 5% black carbon. Organic aerosol (OA) source
apportionment was done using positive matrix factorization (PMF), solved using an advanced multi-linear engine (ME-2) model.
Highly mass-resolved OA mass spectra at one urban and downwind site were factorized into three primary organic aerosol
(POA) factors including one traffic-related and two solid-fuel combustion (SFC), and three oxidized OA (OOA) factors.
Whereas unit mass resolution OA at the other urban site was factorized into two POA factors related to traffic and SFC, and one
OOA factor. OOA constituted a majority of the total OA mass (45-55)% with maximum contribution during afternoon hours
~(70-80)%. Significant differences in the absolute OOA concentration between the two urban sites indicated the influence of local emissions on the oxidized OA formation. Similar PM chemical composition, diurnal and temporal variations at the three
sites suggest similar type of sources affecting the particulate pollution in Delhi and adjoining cities, but variability in mass concentration suggest more local influence than regional.
Keywords: source apportionment, air pollution, particulate matter, Delhi
Published in RUNG: 25.01.2021; Views: 3324; Downloads: 0
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59. Aircraft vertical profiles during summertime regional and Saharan dust scenarios over the north-western Mediterranean basin: aerosol optical and physical propertiesJesús Yus-Díez, Marina Ealo, Marco Pandolfi, Noemi Perez, Gloria Titos, Griša Močnik, Xavier Querol, A. Alastuey, 2021, original scientific article Abstract: Accurate measurements of the horizontal and vertical distribution of atmospheric aerosol particle optical properties are key for a better understanding of their impact on the climate. Here we present the results of a measurement campaign based on instrumented flights over north-eastern Spain. We measured vertical profiles of size-segregated atmospheric particulate matter (PM) mass concentrations and multi-wavelength scattering and absorption coefficients in the western Mediterranean basin (WMB). The campaign took place during typical summer conditions, characterized by the development of a vertical multi-layer structure, under both summer regional pollution episodes (REGs) and Saharan dust events (SDEs). REG patterns in the region form under high insolation and scarce precipitation in summer, favouring layering of highly aged fine-PM strata in the lower few kma.s.l.
The REG scenario prevailed during the entire measurement campaign. Additionally, African dust outbreaks and plumes from northern African wildfires influenced the study area. The vertical profiles of climate-relevant intensive optical parameters such as single-scattering albedo (SSA); the asymmetry parameter (g); scattering, absorption and SSA Ångström exponents (SAE, AAE and SSAAE); and PM mass scattering and absorption cross sections (MSC and MAC) were derived from the measurements. Moreover, we compared the aircraft measurements with those performed at two GAW–ACTRIS (Global Atmosphere Watch–Aerosol, Clouds and Trace Gases) surface measurement stations located in north-eastern Spain, namely Montseny (MSY; regional background) and Montsec d'Ares (MSA; remote site).
Airborne in situ measurements and ceilometer ground-based remote measurements identified aerosol air masses at altitudes up to more than 3.5 kma.s.l.
The vertical profiles of the optical properties markedly changed according to the prevailing atmospheric scenarios. During SDE the SAE was low along the profiles, reaching values < 1.0 in the dust layers. Correspondingly, SSAAE was negative, and AAE reached values up to 2.0–2.5, as a consequence of the UV absorption increased by the presence of the coarse dust particles. During REG, the SAE increased to > 2.0, and the asymmetry parameter g was rather low (0.5–0.6) due to the prevalence of fine PM, which was characterized by an AAE close to 1.0, suggesting a fossil fuel combustion origin. During REG, some of the layers featured larger AAE (> 1.5), relatively low SSA at 525 nm (< 0.85) and high MSC (> 9 m2 g−1) and were associated with the influence of PM from wildfires. Overall, the SSA and MSC near the ground ranged around 0.85 and 3 m2 g−1, respectively, and increased at higher altitudes, reaching values above 0.95 and up to 9 m2 g−1. The PM, MSC and MAC were on average larger during REG compared to SDE due to the larger scattering and absorption efficiency of fine PM compared with dust. The SSA and MSC had quite similar vertical profiles and often both increased with height indicating the progressive shift toward PM with a larger scattering efficiency with altitude.
This study contributes to our understanding of regional-aerosol vertical distribution and optical properties in the WMB, and the results will be useful for improving future climate projections and remote sensing or satellite retrieval algorithms.
Keywords: aerosol, climate change, Saharan dust, black carbon, aerosol absorption, aerosol scattering
Published in RUNG: 14.01.2021; Views: 2378; Downloads: 0
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60. Hidden black carbon air pollution in hilly rural areas - a case study of Dinaric depressionKristina Glojek, Asta Gregorič, Griša Močnik, Andrea Cuesta-Mosquera, A. Wiedensohler, Luka Drinovec, Matej Ogrin, 2020, original scientific article Abstract: Air pollution is not an exclusively urban problem as wood burning is a widespread practice in rural areas. As we lack information on the air quality situation in rural mountainous regions, our aim is to examine equivalent black carbon (eBC) pollution in a typical rural karst area in the settlement of Loški Potok (Slovenia). eBC mass concentrations were measured by Aethalometer (AE-33) at two sites in Retje karst depression. The rural village station was located at the bottom of the karst depression whereas the rural background station was positioned at the top of the hill. We showthe diurnal variation of equivalent black carbon mass concentrations for different seasons. In the populated karst depression, the major source of eBC pollution are households using wood as a heating fuel reaching the highest mass concentrations in winter. Diurnal pattern of eBC from biomass burning and traffic differ due to different source activity and it is influenced by typical formation of a cold air pool from late afternoon until late morning, restricting the dispersion of local emissions. The large difference in mass concentrations between the lowest part of the village (rural station) and the top of the hill (rural background station) indicates that in a vertically stratified and stable atmosphere local sources of black carbon have a major impact onair quality conditions in the area studied. Since in Alpine and Dinaric regions there are many similar inhabited areas, we can expect similar air quality conditions also in other rural hilly areas with limited self-cleaning air capacity.
Keywords: air pollution, black carbon, hidden geographies, diurnal variation, biomass burning, relief depressions, Loški Potok, Slovenia
Published in RUNG: 04.01.2021; Views: 2325; Downloads: 0
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