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@ARTICLE{Tang:1020603,
      author       = {Tang, Angela C. I. and Flechard, Christophe R. and Arriga,
                      Nicola and Papale, Dario and Stoy, Paul. C. and Buchmann,
                      Nina and Cuntz, Matthias and Douros, John and Fares, Silvano
                      and Knohl, Alexander and Šigut, Ladislav and Simioni,
                      Guillaume and Timmermans, Renske and Grünwald, Thomas and
                      Ibrom, Andreas and Loubet, Benjamin and Mammarella, Ivan and
                      Belelli Marchesini, Luca and Nilsson, Mats B. and Peichl,
                      Matthias and Rebmann, Corinna and Schmidt, Marius and
                      Bernhofer, Christian and Berveiller, Daniel and Cremonese,
                      Edoardo and El-Madany, Tarek S. and Gharun, Mana and
                      Gianelle, Damiano and Hörtnagl, Lukas and Roland, Marilyn
                      and Varlagin, Andrej and Fu, Zheng and Heinesch, Bernard and
                      Janssens, Ivan A. and Kowalska, Natalia and Dušek, Jiří
                      and Gerosa, Giacomo and Mölder, Meelis and Tuittila,
                      Eeva-Stiina and Loustau, Denis},
      title        = {{D}etection and {A}ttribution of an {A}nomaly in
                      {T}errestrial {P}hotosynthesis in {E}urope {D}uring the
                      {C}ovid-19 {L}ockdown},
      journal      = {The science of the total environment},
      volume       = {903},
      issn         = {0048-9697},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier Science},
      reportid     = {FZJ-2024-00298},
      pages        = {1-14 / 166149},
      year         = {2023},
      abstract     = {Carbon dioxide (CO2) uptake by plant photosynthesis,
                      referred to as gross primary production (GPP) at the
                      ecosystem level, is sensitive to environmental factors,
                      including pollutant exposure, pollutant uptake, and changes
                      in the scattering of solar shortwave irradiance (SWin) −
                      the energy source for photosynthesis. The 2020 spring
                      lockdown due to COVID-19 resulted in improved air quality
                      and atmospheric transparency, providing a unique opportunity
                      to assess the impact of air pollutants on terrestrial
                      ecosystem functioning. However, detecting these effects can
                      be challenging as GPP is influenced by other meteorological
                      drivers and management practices. Based on data collected
                      from 44 European ecosystem-scale CO2 flux monitoring
                      stations, we observed significant changes in spring GPP at
                      34 sites during 2020 compared to 2015–2019. Among these,
                      14 sites showed an increase in GPP associated with higher
                      SWin, 10 sites had lower GPP linked to atmospheric and soil
                      dryness, and seven sites were subjected to management
                      practices. The remaining three sites exhibited varying
                      dynamics, with one experiencing colder and rainier weather
                      resulting in lower GPP, and two showing higher GPP
                      associated with earlier spring melts. Analysis using the
                      regional atmospheric chemical transport model (LOTOS-EUROS)
                      indicated that the ozone (O3) concentration remained
                      relatively unchanged at the research sites, making it
                      unlikely that O3 exposure was the dominant factor driving
                      the primary production anomaly. In contrast, SWin increased
                      by 9.4 $\%$ at 36 sites, suggesting enhanced GPP possibly
                      due to reduced aerosol optical depth and cloudiness. Our
                      findings indicate that air pollution and cloudiness may
                      weaken the terrestrial carbon sink by up to 16 $\%.$
                      Accurate and continuous ground-based observations are
                      crucial for detecting and attributing subtle changes in
                      terrestrial ecosystem functioning in response to
                      environmental and anthropogenic drivers.},
      cin          = {IBG-3},
      ddc          = {610},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {2173 - Agro-biogeosystems: controls, feedbacks and impact
                      (POF4-217)},
      pid          = {G:(DE-HGF)POF4-2173},
      typ          = {PUB:(DE-HGF)16},
      doi          = {10.1016/j.scitotenv.2023.166149},
      url          = {https://juser.fz-juelich.de/record/1020603},
}