1. Changes in black carbon emissions over Europe due to COVID-19 lockdownsNikolaos Evangeliou, Stephen M. Platt, Sabine Eckhardt, Cathrine Lund Myhre, Paolo Laj, L. Alados-Arboledas, John Backman, Benjamin T. Brem, Markus Fiebig, Jesús Yus-Díez, 2021, izvirni znanstveni članek Opis: Abstract. Following 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.
Ključne besede: black carbon, covid-19, emissions, Europe
Objavljeno v RUNG: 13.05.2024; Ogledov: 12; Prenosov: 0
 Celotno besedilo (11,03 MB)
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2. Recommendations for reporting equivalent black carbon (eBC) mass concentrations based on long-term pan-European in-situ observationsMarjan Savadkoohi, Marco Pandolfi, Olivier Favez, Jean-Philippe Putaud, Konstantinos Eleftheriadis, Markus Fiebig, Philip Hopke, Paolo Laj, A. Wiedensohler, Griša Močnik, 2024, izvirni znanstveni članek Opis: A reliable determination of equivalent black carbon (eBC) mass concentrations derived from filter absorption photometers (FAPs) measurements depends on the appropriate quantification of the mass absorption cross-section (MAC) for converting the absorption coefficient (babs) to eBC. This study investigates the spatial–temporal variability of the MAC obtained from simultaneous elemental carbon (EC) and babs measurements performed at 22 sites. We compared different methodologies for retrieving eBC integrating different options for calculating MAC including: locally derived, median value calculated from 22 sites, and site-specific rolling regression MAC. The eBC concentrations that underwent correction using these methods were identified as LeBC (local MAC), MeBC (median MAC), and ReBC (Rolling MAC) respectively. Pronounced differences (up to more than 50 %) were observed between eBC as directly provided by FAPs (NeBC; Nominal instrumental MAC) and ReBC due to the differences observed between the experimental and nominal MAC values. The median MAC was 7.8 ± 3.4 m2/g from 12 aethalometers at 880 nm, and 10.6 ± 4.7 m2/g from 10 MAAPs at 637 nm. The experimental MAC showed significant site and seasonal dependencies, with heterogeneous patterns between summer and winter in different regions. In addition, long-term trend analysis revealed statistically significant (s.s.) decreasing trends in EC. Interestingly, we showed that the corresponding corrected eBC trends are not independent of the way eBC is calculated due to the variability of MAC. NeBC and EC decreasing trends were consistent at sites with no significant trend in experimental MAC. Conversely, where MAC showed s.s. trend, the NeBC and EC trends were not consistent while ReBC concentration followed the same pattern as EC. These results underscore the importance of accounting for MAC variations when deriving eBC measurements from FAPs and emphasizes the necessity of incorporating EC observations to constrain the uncertainty associated with eBC.
Ključne besede: equivalent black carbon, mass absorption cross-section, filter absorption photometers, elemental carbon, absorption, site specific MAC, rolling MAC
Objavljeno v RUNG: 04.03.2024; Ogledov: 381; Prenosov: 3
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