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- ItemIntercomparison and characterization of 23 Aethalometers under laboratory and ambient air conditions: procedures and unit-to-unit variabilities(Katlenburg-Lindau : European Geosciences Union, 2021) Cuesta-Mosquera, Andrea; Močnik, Griša; Drinovec, Luka; Müller, Thomas; Pfeifer, Sascha; Minguillón, María Cruz; Briel, Björn; Buckley, Paul; Dudoitis, Vadimas; Fernández-García, Javier; Fernández-Amado, María; Ferreira De Brito, Joel; Riffault, Veronique; Flentje, Harald; Heffernan, Eimear; Kalivitis, Nikolaos; Kalogridis, Athina-Cerise; Keernik, Hannes; Marmureanu, Luminita; Luoma, Krista; Marinoni, Angela; Pikridas, Michael; Schauer, Gerhard; Serfozo, Norbert; Servomaa, Henri; Titos, Gloria; Yus-Díez, Jesús; Zioła, Natalia; Wiedensohler, AlfredAerosolized 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 qualitychecked 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 wellcharacterized 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 wellmaintained 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. © 2021 Author(s). This work is distributed under the Creative Commons Attribution 4.0 License.
- ItemChanges in black carbon emissions over Europe due to COVID-19 lockdowns(Katlenburg-Lindau : European Geosciences Union, 2021) Evangeliou, Nikolaos; Platt, Stephen M.; Eckhardt, Sabine; Lund Myhre, Cathrine; Laj, Paolo; Alados-Arboledas, Lucas; Backman, John; Brem, Benjamin T.; Fiebig, Markus; Flentje, Harald; Marinoni, Angela; Pandolfi, Marco; Yus-Dìez, Jesus; Prats, Natalia; Putaud, Jean P.; Sellegri, Karine; Sorribas, Mar; Eleftheriadis, Konstantinos; Vratolis, Stergios; Wiedensohler, Alfred; Stohl, AndreasFollowing the emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) responsible for COVID-19 in December 2019 in Wuhan (China) and its spread to the rest of the world, the World Health Organization declared a global pandemic in March 2020. Without effective treatment in the initial pandemic phase, social distancing and mandatory quarantines were introduced as the only available preventative measure. In contrast to the detrimental societal impacts, air quality improved in all countries in which strict lockdowns were applied, due to lower pollutant emissions. Here we investigate the effects of the COVID-19 lockdowns in Europe on ambient black carbon (BC), which affects climate and damages health, using in situ observations from 17 European stations in a Bayesian inversion framework. BC emissions declined by 23 kt in Europe (20 % in Italy, 40 % in Germany, 34 % in Spain, 22 % in France) during lockdowns compared to the same period in the previous 5 years, which is partially attributed to COVID-19 measures. BC temporal variation in the countries enduring the most drastic restrictions showed the most distinct lockdown impacts. Increased particle light absorption in the beginning of the lockdown, confirmed by assimilated satellite and remote sensing data, suggests residential combustion was the dominant BC source. Accordingly, in central and Eastern Europe, which experienced lower than average temperatures, BC was elevated compared to the previous 5 years. Nevertheless, an average decrease of 11 % was seen for the whole of Europe compared to the start of the lockdown period, with the highest peaks in France (42 %), Germany (21 %), UK (13 %), Spain (11 %) and Italy (8 %). Such a decrease was not seen in the previous years, which also confirms the impact of COVID-19 on the European emissions of BC.