03 Jun 2022
03 Jun 2022
Status: this preprint is currently under review for the journal ACP.

Stratospheric water vapor and ozone response to different QBO disruption events in 2016 and 2020

Mohamadou A. Diallo1, Felix Ploeger1,2, Michaela I. Hegglin1,2,3, Manfred Ern1, Jens-Uwe Grooß1, Sergey Khaykin4, and Martin Riese1,2 Mohamadou A. Diallo et al.
  • 1Institute of Energy and Climate Research, Stratosphere (IEK–7), Forschungszentrum Jülich, 52 425 Jülich, Germany
  • 2Institute for Atmospheric and Environmental Research, University of Wuppertal, Wuppertal, Germany
  • 3Department of Meteorology, University of Reading, Reading, UK
  • 4Laboratoire Atmosphères, Milieux, Observations Spatiales, UMR CNRS 8190, IPSL, Sorbonne Univ./UVSQ, Guyancourt, France

Abstract. The Quasi-Biennial Oscillation (QBO) is a major mode of climate variability with periodically descending westerly and easterly winds in the tropical stratosphere, modulating transport and distributions of key greenhouse gases such as water vapor and ozone. In 2016 and 2020, anomalous QBO easterlies disrupted the QBO’s 28–month period previously observed. Here, we quantify the impact of these two QBO disruption events on the Brewer–Dobson circulation, water vapour and ozone using the ERA5 reanalysis and satellite observations, respectively. Both lower stratospheric trace gases decrease globally during the 2015–2016 QBO disruption event, while they only weakly decrease during the 2019–2020 QBO disruption event. These dissimilarities in the circulation anomalous response to the QBO disruption events result from differences in the tropical upwelling caused by anomalous planetary and gravity wave forcing in the lower stratosphere near the equatorward flanks of the subtropical jet. The differences in the response of lower stratospheric water vapor to the 2015–2016 and 2019–2020 QBO disruption events are due to the cold–point temperature differences induced by the Australian wildfire, which moistened the lower stratosphere, therefore, hidding the 2019–2020 QBO disruption impact. Our results highlight the need for a better understanding of the causes of QBO disruption events, their interplay with other climate variability modes, and their impacts on water vapor and ozone in the face of a changing climate.

Mohamadou A. Diallo et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-382', Anonymous Referee #1, 14 Jun 2022
  • RC2: 'Comment on acp-2022-382', Anonymous Referee #2, 30 Jun 2022
  • RC3: 'Comment on acp-2022-382', Anonymous Referee #3, 30 Jun 2022

Mohamadou A. Diallo et al.

Mohamadou A. Diallo et al.


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Short summary
The QBO disruption events in both 2016 and 2020 decreased lower stratospheric water vapor and ozone. Differences in the strength and depth of the anomalous lower stratospheric circulation, ozone and water vapor are due to differences in tropical upwelling and cold point temperature. Tropical upwelling differences are due to lower stratospheric planetary and gravity wave breaking and cold point temperature differences to Australian wildfire.