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@ARTICLE{Ploeger:893188,
      author       = {Ploeger, Felix and Diallo, Mohamadou and Charlesworth,
                      Edward and Konopka, Paul and Legras, Bernard and Laube,
                      Johannes C. and Grooß, Jens-Uwe and Günther, Gebhard and
                      Engel, Andreas and Riese, Martin},
      title        = {{T}he stratospheric {B}rewer–{D}obson circulation
                      inferred from age of air in the {ERA}5 reanalysis},
      journal      = {Atmospheric chemistry and physics},
      volume       = {21},
      number       = {11},
      issn         = {1680-7324},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {FZJ-2021-02612},
      pages        = {8393 - 8412},
      year         = {2021},
      abstract     = {This paper investigates the global stratospheric
                      Brewer–Dobson circulation (BDC) in the ERA5 meteorological
                      reanalysis from the European Centre for Medium-Range Weather
                      Forecasts (ECMWF). The analysis is based on simulations of
                      stratospheric mean age of air, including the full age
                      spectrum, with the Lagrangian transport model CLaMS
                      (Chemical Lagrangian Model of the Stratosphere), driven by
                      reanalysis winds and total diabatic heating rates.
                      ERA5-based results are compared to results based on the
                      preceding ERA-Interim reanalysis. Our results show a
                      significantly slower BDC for ERA5 than for ERA-Interim,
                      manifesting in weaker diabatic heating rates and higher age
                      of air. In the tropical lower stratosphere, heating rates
                      are $30 \%–40 \%$ weaker in ERA5, likely correcting a
                      bias in ERA-Interim. At 20 km and in the Northern
                      Hemisphere (NH) stratosphere, ERA5 age values are around the
                      upper margin of the uncertainty range from historical tracer
                      observations, indicating a somewhat slow–biased BDC. The
                      age trend in ERA5 over the 1989–2018 period is negative
                      throughout the stratosphere, as climate models predict in
                      response to global warming. However, the age decrease is not
                      linear but steplike, potentially caused by multi-annual
                      variability or changes in the observations included in the
                      assimilation. During the 2002–2012 period, the ERA5 age
                      shows a similar hemispheric dipole trend pattern as
                      ERA-Interim, with age increasing in the NH and decreasing in
                      the Southern Hemisphere (SH). Shifts in the age spectrum
                      peak and residual circulation transit times indicate that
                      reanalysis differences in age are likely caused by
                      differences in the residual circulation. In particular, the
                      shallow BDC branch accelerates in both reanalyses, whereas
                      the deep branch accelerates in ERA5 and decelerates in
                      ERA-Interim.},
      cin          = {IEK-7},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {2112 - Climate Feedbacks (POF4-211) / DFG project 429838442
                      - Wie wirken sich natürliche Variabilität und anthropogen
                      bedingte Änderungen auf die stratosphärische Brewer-Dobson
                      Zirkulation und den Ozonfluss in die Troposphäre aus?},
      pid          = {G:(DE-HGF)POF4-2112 / G:(GEPRIS)429838442},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000659136400002},
      doi          = {10.5194/acp-21-8393-2021},
      url          = {https://juser.fz-juelich.de/record/893188},
}