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@ARTICLE{Diallo:911982,
      author       = {Diallo, Mohamadou A. and Ploeger, Felix and Hegglin,
                      Michaela Imelda and Ern, Manfred and Grooß, Jens-Uwe and
                      Khaykin, Sergey and Riese, Martin},
      title        = {{S}tratospheric water vapour and ozone response to the
                      quasi-biennial oscillation disruptions in 2016 and 2020},
      journal      = {Atmospheric chemistry and physics},
      volume       = {22},
      number       = {21},
      issn         = {1680-7316},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {FZJ-2022-05212},
      pages        = {14303 - 14321},
      year         = {2022},
      abstract     = {The quasi-biennial oscillation (QBO) is a major mode of
                      climate variability in the tropical stratosphere with
                      quasi-periodically descending westerly and easterly winds,
                      modulating transport and distributions of key greenhouse
                      gases such as water vapour and ozone. In 2016 and 2020,
                      anomalous QBO easterlies disrupted the QBO's mean period of
                      about 28 months previously observed. Here, we quantify the
                      impact of these two QBO disruption events on the
                      Brewer–Dobson circulation and respective distributions of
                      water vapour and ozone using the ERA5 reanalysis and
                      Microwave Limb Sounder (MLS) satellite observations,
                      respectively. In 2016, both water vapour and ozone in the
                      lower stratosphere decreased globally during the QBO
                      disruption event by up to about $20 \%.$ In 2020, the
                      lower-stratospheric ozone only weakly decreased during the
                      QBO disruption event, by up to about $10 \%,$ while the
                      lower-stratospheric water vapour increased by up to about
                      $15 \%.$ These dissimilarities in the anomalous
                      circulation and the related ozone response between the year
                      2016 and the year 2020 result from differences in the
                      tropical upwelling and in the secondary circulation of the
                      QBO caused by differences in anomalous planetary and gravity
                      wave breaking in the lower stratosphere near the equatorward
                      upper flanks of the subtropical jet. The anomalous planetary
                      and gravity wave breaking was stronger in the lower
                      stratosphere between the tropopause and the altitude of
                      about 23 km during the QBO disruption events in 2016 than
                      in 2020. However, the differences in the response of
                      lower-stratospheric water vapour to the QBO disruption
                      events between the year 2016 and the year 2020 are mainly
                      due to the differences in cold-point temperatures induced by
                      Australian wildfire, which moistened the lower stratosphere,
                      thereby obscuring the impact of the QBO disruption event in
                      2020 on water vapour in the lower stratosphere. Our results
                      highlight the need for a better understanding of the causes
                      of the QBO disruption, their interplay with other modes of
                      climate variability in the Indo-Pacific region, including
                      the El Niño–Southern Oscillation (ENSO) and the Indian
                      Ocean Dipole (IOD), and their impacts on water vapour and
                      ozone in the upper troposphere/lower stratosphere in the
                      face of a changing climate.},
      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:000879750300001},
      doi          = {10.5194/acp-22-14303-2022},
      url          = {https://juser.fz-juelich.de/record/911982},
}