Cleaner Skies during the COVID-19 Lockdown

Voigt, Christiane; Lelieveld, J.; Schläger, Hans; Schneider, Johannes; Curtius, Joachim; Meerkötter, R.; Sauer, Daniel; Bugliaro, Luca; Bohn, Birger; Crowley, John N.; Erbertseder, Thilo; Groβ, Silke; Hahn, Valerian; Li, Qiang; Mertens, Mariano; Pöhlker, Mira L.; Pozzer, Andrea; Schumann, U.; Tomsche, Laura; Williams, Jonathan; Zahn, Andreas; Borrmann, Stephan; Bräuer, Tiziana; Dörich, Raphael; Dörnbrack, Andreas; Edtbauer, Achim; Ernle, Lisa; Fischer, H.; Giez, Andreas; Granzin, Manuel; Grewe, Volker; Harder, Hartwig; Heinritzi, Martin; Holanda, Bruna A.; Jöckel, Patrick; Kaiser, Katharina; Krüger, Ovid O.; Lucke, Johannes; Marsing, Andreas; Martin, A.; Matthes, Sigrun; Pöhlker, Christopher; Pöschl, Ulrich; Reifenberg, Simon F.; Ringsdorf, Akima; Scheibe, Monika; Tadić, Ivan; Zauner-Wieczorek, Marcel; Henke, Rolf; Rapp, Markus

doi:10.1175/bams-d-21-0012.1

Cited by 37 publications

(31 citation statements)

References 108 publications

(64 reference statements)

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“…We compare the results of EMeRGe EU to BLUESKY including the CAFE EU project (Chemistry of the Atmosphere: Field Experiment in Europe), from 23 May until 9 June 2020 (Voigt et al, 2022). The central point during BLUESKY was to investigate the effects of the COVID-19 confinements on the atmosphere.…”

Section: Studied Areamentioning

confidence: 99%

“…4,6 and 5), is that during BLUESKY in 2020 low air traffic volume allowed us to perform more near-surface measurement flights. These measurements also include manoeuvres referred to as low approaches (Voigt et al, 2022), i.e. a landing manoeuvre without ground contact followed by a take-off.…”

Section: Studied Areamentioning

confidence: 99%

“…The measurements were carried out with a single particle soot photometer (SP2) mounted on the HALO (High Altitude and LOng range) research aircraft. This study compares data from in situ measurements during non-confinement conditions in July 2017 (during the EMeRGe EU campaign, Andrés Hernández et al, 2022) with those affected by reduced emissions in May and June 2020 (during the BLUESKY campaign, Voigt et al, 2022). The measurements were performed while most of the lockdown confinements were still active; however, the strictest lockdown was between the middle of March until the middle of May (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Black carbon aerosol reductions during COVID-19 confinement quantified by aircraft measurements over Europe

et al. 2022

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Abstract. The abrupt reduction in human activities during the first lockdown of the COVID-19 pandemic created unprecedented atmospheric conditions. To quantify the changes in lower tropospheric air pollution, we conducted the BLUESKY aircraft campaign and measured vertical profiles of black carbon (BC) aerosol particles over western and southern Europe in May and June 2020. We compared the results to similar measurements of the EMeRGe EU campaign performed in July 2017 and found that the BC mass concentrations (MBC) were reduced by about 48 %. For BC particle number concentrations, we found comparable reductions. Based on ECHAM/MESSy Atmospheric Chemistry (EMAC) chemistry-transport model simulations, we found differences in meteorological conditions and flight patterns responsible for about 7 % of the MBC reductions. Accordingly 41 % of MBC reductions can be attributed to reduced anthropogenic emissions. Our results reflect the strong and immediate positive effect of changes in human activities on air quality and the atmospheric role of BC aerosols as a major air pollutant in the Anthropocene.

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Section: Studied Areamentioning

confidence: 99%

Section: Studied Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Black carbon aerosol reductions during COVID-19 confinement quantified by aircraft measurements over Europe

et al. 2022

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“…The decrease in air pollution and aircraft emissions provided a unique opportunity for analysis of the resulting changes in the atmosphere. The reduced pollution levels gave rise to anomalous blue skies, hence the name "BLUESKY" (Voigt et al, 2022). The project was carried out in May and June 2020 covering an area from the Mediterranean region in southern Europe (approximately 35 • N) up to the North Atlantic flight corridor (approximately 60 • N).…”

Section: Bluesky Campaign Descriptionmentioning

confidence: 99%

Distribution of hydrogen peroxide over Europe during the BLUESKY aircraft campaign

et al. 2022

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Abstract. In this work we present airborne in situ trace gas observations of hydrogen peroxide (H2O2) and the sum of organic hydroperoxides over Europe during the Chemistry of the Atmosphere – Field Experiments in Europe (CAFE-EU, also known as BLUESKY) aircraft campaign using a wet chemical monitoring system, the HYdrogen Peroxide and Higher Organic Peroxide (HYPHOP) monitor. The campaign took place in May–June 2020 over central and southern Europe with two additional flights dedicated to the North Atlantic flight corridor. Airborne measurements were performed on the High Altitude and LOng-range (HALO) research operating out of Oberpfaffenhofen (southern Germany). We report average mixing ratios for H2O2 of 0.32 ± 0.25, 0.39 ± 0.23 and 0.38 ± 0.21 ppbv in the upper and middle troposphere and the boundary layer over Europe, respectively. Vertical profiles of measured H2O2 reveal a significant decrease, in particular above the boundary layer, contrary to previous observations, most likely due to cloud scavenging and subsequent rainout of soluble species. In general, the expected inverted C-shaped vertical trend with maximum hydrogen peroxide mixing ratios at 3–7 km was not found during BLUESKY. This deviates from observations during previous airborne studies over Europe, i.e., 1.64 ± 0.83 ppbv during the HOOVER campaign and 1.67 ± 0.97 ppbv during UTOPIHAN-ACT II/III. Simulations with the global chemistry–transport model EMAC partly reproduce the strong effect of rainout loss on the vertical profile of H2O2. A sensitivity study without H2O2 scavenging performed using EMAC confirms the strong influence of clouds and precipitation scavenging on hydrogen peroxide concentrations. Differences between model simulations and observations are most likely due to difficulties in the simulation of wet scavenging processes due to the limited model resolution.

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“…Satellite-based observations revealed up to 50% reductions in boundary layer NO 2 over urban areas of Europe [ 101 ]. The aircraft-based measurements under the BLUESKY campaign showed large variabilities in reactive nitrogen and aerosols (20–70%) over German cities during the lockdown as compared to multi-year average data [ 101 ]. In situ measurements across the UK also showed reductions in NO 2 (up to 48%) but a slight increase in O 3 by ~11% [ 102 ].…”

Section: Covid-19 Lockdown: a Reality Checkmentioning

confidence: 99%

Mechanisms and Pathways for Coordinated Control of Fine Particulate Matter and Ozone

et al. 2022

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Purpose of Review Fine particulate matter (PM 2.5 ) and ground-level ozone (O 3 ) pose a significant risk to human health. The World Health Organization (WHO) has recently revised healthy thresholds for both pollutants. The formation and evolution of PM 2.5 and O 3 are however governed by complex physical and multiphase chemical processes, and therefore, it is extremely challenging to mitigate both pollutants simultaneously. Here, we review mechanisms and discuss the science-informed pathways for effective and simultaneous mitigation of PM 2.5 and O 3 . Recent Findings Global warming has led to a general increase in biogenic emissions, which can enhance the formation of O 3 and secondary organic aerosols. Reductions in anthropogenic emissions during the COVID-19 lockdown reduced PM 2.5 ; however, O 3 was enhanced in several polluted regions. This was attributed to more intense sunlight due to low aerosol loading and non-linear response of O 3 to NO x . Such contrasting physical and chemical interactions hinder the formulation of a clear roadmap for clean air over such regions. Summary Atmospheric chemistry including the role of biogenic emissions, aerosol-radiation interactions, boundary layer, and regional-scale transport are the key aspects that need to be carefully considered in the formulation of mitigation pathways. Therefore, a thorough understanding of the chemical effects of the emission reductions, changes in photolytic rates and boundary layer due to perturbation of solar radiation, and the effect of meteorological/seasonal changes are needed on a regional basis. Statistical emulators and machine learning approaches can aid the cumbersome process of multi-sector multi-species source attribution.

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Cleaner Skies during the COVID-19 Lockdown

Cited by 37 publications

References 108 publications

Black carbon aerosol reductions during COVID-19 confinement quantified by aircraft measurements over Europe

Black carbon aerosol reductions during COVID-19 confinement quantified by aircraft measurements over Europe

Distribution of hydrogen peroxide over Europe during the BLUESKY aircraft campaign

Mechanisms and Pathways for Coordinated Control of Fine Particulate Matter and Ozone

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