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@ARTICLE{Voigt:912324,
      author       = {Voigt, Christiane and Lelieveld, Jos and Schlager, Hans and
                      Schneider, Johannes and Curtius, Joachim and Meerkötter,
                      Ralf and Sauer, Daniel and Bugliaro, Luca and Bohn, Birger
                      and Crowley, John N. and Erbertseder, Thilo and Groß, Silke
                      and Hahn, Valerian and Li, Qiang and Mertens, Mariano and
                      Pöhlker, Mira L. and Pozzer, Andrea and Schumann, Ulrich
                      and Tomsche, Laura and Williams, Jonathan and Zahn, Andreas
                      and Andreae, Meinrat and Borrmann, Stephan and Bräuer,
                      Tiziana and Dörich, Raphael and Dörnbrack, Andreas and
                      Edtbauer, Achim and Ernle, Lisa and Fischer, Horst and Giez,
                      Andreas and Granzin, Manuel and Grewe, Volker and Harder,
                      Hartwig and Heinritzi, Martin and Holanda, Bruna A. and
                      Jöckel, Patrick and Kaiser, Katharina and Krüger, Ovid O.
                      and Lucke, Johannes and Marsing, Andreas and Martin, Anna
                      and Matthes, Sigrun and Pöhlker, Christopher and Pöschl,
                      Ulrich and Reifenberg, Simon and Ringsdorf, Akima and
                      Scheibe, Monika and Tadic, Ivan and Zauner-Wieczorek, Marcel
                      and Henke, Rolf and Rapp, Markus},
      title        = {{C}leaner {S}kies during the {COVID}-19 {L}ockdown},
      journal      = {Bulletin of the American Meteorological Society},
      volume       = {103},
      number       = {8},
      issn         = {0003-0007},
      address      = {Boston, Mass.},
      publisher    = {ASM},
      reportid     = {FZJ-2022-05516},
      pages        = {E1796 - E1827},
      year         = {2022},
      abstract     = {During spring 2020, the COVID-19 pandemic caused massive
                      reductions in emissions from industry and ground and
                      airborne transportation. To explore the resulting
                      atmospheric composition changes, we conducted the BLUESKY
                      campaign with two research aircraft and measured trace
                      gases, aerosols, and cloud properties from the boundary
                      layer to the lower stratosphere. From 16 May to 9 June 2020,
                      we performed 20 flights in the early COVID-19 lockdown phase
                      over Europe and the Atlantic Ocean. We found up to $50\%$
                      reductions in boundary layer nitrogen dioxide concentrations
                      in urban areas from GOME-2B satellite data, along with
                      carbon monoxide reductions in the pollution hot spots. We
                      measured $20\%–70\%$ reductions in total reactive
                      nitrogen, carbon monoxide, and fine mode aerosol
                      concentration in profiles over German cities compared to a
                      10-yr dataset from passenger aircraft. The total aerosol
                      mass was significantly reduced below 5 km altitude, and the
                      organic aerosol fraction also aloft, indicative of decreased
                      organic precursor gas emissions. The reduced aerosol optical
                      thickness caused a perceptible shift in sky color toward the
                      blue part of the spectrum (hence BLUESKY) and increased
                      shortwave radiation at the surface. We find that the $80\%$
                      decline in air traffic led to substantial reductions in
                      nitrogen oxides at cruise altitudes, in contrail cover, and
                      in resulting radiative forcing. The light extinction and
                      depolarization by cirrus were also reduced in regions with
                      substantially decreased air traffic. General
                      circulation–chemistry model simulations indicate good
                      agreement with the measurements when applying a reduced
                      emission scenario. The comprehensive BLUESKY dataset
                      documents the major impact of anthropogenic emissions on the
                      atmospheric composition.},
      cin          = {IEK-8},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-8-20101013},
      pnm          = {2111 - Air Quality (POF4-211)},
      pid          = {G:(DE-HGF)POF4-2111},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000886646700005},
      doi          = {10.1175/BAMS-D-21-0012.1},
      url          = {https://juser.fz-juelich.de/record/912324},
}