Stratospheric water vapor and ozone response to different QBO disruption
events in 2016 and 2020
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 QBO disruptions on lower
stratospheric circulation, and water vapour and ozone using reanalyses
and satellite observations, respectively. Both constituents decrease
globally from early spring to late autumn during 2016, while they only
weakly decrease during 2020. These dissimilarities result from
differences in upwelling and cold-point tropopause temperatures caused
by anomalous planetary and gravity wave forcing. Our results highlight
the need for a better understanding of the causes of QBO disruptions,
their interplay with other modes of climate variability, and their
impacts on water vapor and ozone in the face of a changing climate.