% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@ARTICLE{Cooper:890221,
      author       = {Cooper, Owen and Schultz, Martin G. and Schröder, Sabine
                      and Chang, Kai-Lan and Gaudel, Audrey and Benítez, Gerardo
                      Carbajal and Cuevas, Emilio and Fröhlich, Marina and
                      Galbally, Ian E. and Molloy, Suzie and Kubistin, Dagmar and
                      Lu, Xiao and McClure-Begley, Audra and Nédélec, Philippe
                      and O’Brien, Jason and Oltmans, Samuel J. and
                      Petropavlovskikh, Irina and Ries, Ludwig and Senik, Irina
                      and Sjöberg, Karin and Solberg, Sverre and Spain, Gerard T.
                      and Spangl, Wolfgang and Steinbacher, Martin and Tarasick,
                      David and Thouret, Valerie and Xu, Xiaobin},
      title        = {{M}ulti-decadal surface ozone trends at globally
                      distributed remote locations},
      journal      = {Elementa},
      volume       = {8},
      issn         = {2325-1026},
      address      = {Washington, DC},
      publisher    = {BioOne},
      reportid     = {FZJ-2021-00810},
      pages        = {23},
      year         = {2020},
      abstract     = {Extracting globally representative trend information from
                      lower tropospheric ozone observations is extremely difficult
                      due to the highly variable distribution and interannual
                      variability of ozone, and the ongoing shift of ozone
                      precursor emissions from high latitudes to low latitudes.
                      Here we report surface ozone trends at 27 globally
                      distributed remote locations (20 in the Northern Hemisphere,
                      7 in the Southern Hemisphere), focusing on continuous time
                      series that extend from the present back to at least 1995.
                      While these sites are only representative of less than
                      $25\%$ of the global surface area, this analysis provides a
                      range of regional long-term ozone trends for the evaluation
                      of global chemistry-climate models. Trends are based on
                      monthly mean ozone anomalies, and all sites have at least 20
                      years of data, which improves the likelihood that a robust
                      trend value is due to changes in ozone precursor emissions
                      and/or forced climate change rather than naturally occurring
                      climate variability. Since 1995, the Northern Hemisphere
                      sites are nearly evenly split between positive and negative
                      ozone trends, while 5 of 7 Southern Hemisphere sites have
                      positive trends. Positive trends are in the range of 0.5–2
                      ppbv decade–1, with ozone increasing at Mauna Loa by
                      roughly $50\%$ since the late 1950s. Two high elevation
                      Alpine sites, discussed by previous assessments, exhibit
                      decreasing ozone trends in contrast to the positive trend
                      observed by IAGOS commercial aircraft in the European lower
                      free-troposphere. The Alpine sites frequently sample
                      polluted European boundary layer air, especially in summer,
                      and can only be representative of lower free tropospheric
                      ozone if the data are carefully filtered to avoid boundary
                      layer air. The highly variable ozone trends at these 27
                      surface sites are not necessarily indicative of free
                      tropospheric trends, which have been overwhelmingly positive
                      since the mid-1990s, as shown by recent studies of
                      ozonesonde and aircraft observations.},
      cin          = {JSC},
      ddc          = {550},
      cid          = {I:(DE-Juel1)JSC-20090406},
      pnm          = {512 - Data-Intensive Science and Federated Computing
                      (POF3-512) / Earth System Data Exploration (ESDE)},
      pid          = {G:(DE-HGF)POF3-512 / G:(DE-Juel-1)ESDE},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000538766300001},
      doi          = {10.1525/elementa.420},
      url          = {https://juser.fz-juelich.de/record/890221},
}