Response of stratospheric water vapor and ozone to the unusual timing of El Niño and the QBO disruption in 2015–2016

摘要

The stratospheric circulation determines the transport and lifetime of keytrace gases in a changing climate, including water vapor and ozone, whichradiatively impact surface climate.The unusually warm El Niño–Southern Oscillation (ENSO) event aligned with adisrupted Quasi-Biennial Oscillation (QBO) caused an unprecedented perturbationto this circulation in 2015–2016.Here, we quantify the impact of the alignment of these two phenomena in 2015–2016on lower stratospheric water vapor and ozone from satellite observations. We showthat the warm ENSO event substantially increased water vapor and decreased ozonein the tropical lower stratosphere.The QBO disruption significantly decreased global lower stratospheric water vaporand tropical ozone from early spring to late autumn.Thus, this QBO disruption reversed the lower stratosphere moistening triggeredby the alignment of the warm ENSO event with westerly QBO in early boreal winter.Our results suggest that the interplay of ENSO events and QBO phases will becrucial for the distributions of radiatively active trace gasesin a changing future climate, when increasing El Niño-like conditions anda decreasing lower stratospheric QBO amplitude are expected.