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@ARTICLE{Ern:1014378,
      author       = {Ern, Manfred and Diallo, Mohamadou A. and Khordakova, Dina
                      and Krisch, Isabell and Preusse, Peter and Reitebuch, Oliver
                      and Ungermann, Jörn and Riese, Martin},
      title        = {{T}he quasi-biennial oscillation ({QBO}) and global-scale
                      tropical waves in {A}eolus wind observations, radiosonde
                      data, and reanalyses},
      journal      = {Atmospheric chemistry and physics},
      volume       = {23},
      number       = {16},
      issn         = {1680-7316},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {FZJ-2023-03279},
      pages        = {9549 - 9583},
      year         = {2023},
      abstract     = {The quasi-biennial oscillation (QBO) of the stratospheric
                      tropical winds influences the global circulation over a wide
                      range of latitudes and altitudes. Although it has strong
                      effects on surface weather and climate, climate models have
                      great difficulties in simulating a realistic QBO, especially
                      in the lower stratosphere. Therefore, global wind
                      observations in the tropical upper troposphere and lower
                      stratosphere (UTLS) are of particular interest for
                      investigating the QBO and the tropical waves that contribute
                      significantly to its driving. In our work, we focus on the
                      years 2018–2022 and investigate the QBO and different
                      tropical wave modes in the UTLS region using global wind
                      observations made by the Aeolus satellite instrument and
                      three meteorological reanalyses: the fifth generation
                      European Centre for Medium-Range Weather Forecasts (ECMWF)
                      reanalysis (ERA-5), the Japanese 55-year Reanalysis (JRA-55)
                      of the Japan Meteorological Agency (JMA), and the Modern-Era
                      Retrospective Analysis for Research and Applications,
                      version 2 (MERRA-2). Further, we compare these data with
                      observations of selected radiosonde stations. By comparison
                      with Aeolus observations, we find that, on zonal average,
                      the QBO in the lower stratosphere is well represented in all
                      three reanalyses, with ERA-5 performing best. Averaged over
                      the years 2018–2022, agreement between Aeolus and the
                      reanalyses is better than 1 to 2 m s−1, with somewhat
                      larger differences during some periods. Differently from
                      zonal averages, radiosonde stations provide only local
                      observations and are therefore biased by global-scale
                      tropical waves, which limits their use as a QBO standard.
                      While reanalyses perform well on zonal average, there can be
                      considerable local biases between reanalyses and
                      radiosondes. We also find that, in the tropical UTLS, zonal
                      wind variances of stationary waves and the most prominent
                      global-scale traveling equatorial wave modes, such as Kelvin
                      waves, Rossby-gravity waves, and equatorial Rossby waves,
                      are in good agreement between Aeolus and all three
                      reanalyses (in most cases better than $20 \%$ of the peak
                      values in the UTLS). On zonal average, this supports the use
                      of reanalyses as a reference for comparison with
                      free-running climate models, while locally, certain biases
                      exist, particularly in the QBO wind shear zones and around
                      the 2019–2020 QBO disruption.},
      cin          = {IEK-7},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {2112 - Climate Feedbacks (POF4-211) / 2A3 - Remote Sensing
                      (CARF - CCA) (POF4-2A3)},
      pid          = {G:(DE-HGF)POF4-2112 / G:(DE-HGF)POF4-2A3},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:001167516500001},
      doi          = {10.5194/acp-23-9549-2023},
      url          = {https://juser.fz-juelich.de/record/1014378},
}