Tropical Stratospheric Circulation and Ozone Coupled to Pacific Multi-Decadal Variability

Abstract

Natural variability is a key element of the climate system and can mask human-induced changes. Here, we are interested in the naturally varying strength of the stratospheric global circulation and how this impacts the composition of the stratosphere. Using observations and model simulations, we show that slowly changing (multi-decadal) natural variability in the Pacific Ocean is reflected in the stratospheric circulation. This link helps us to better understand structural changes in the stratospheric circulation arising due to human interferences. In turn, slow transport variability reconciles recent low levels of ozone in the middle tropical stratosphere, which otherwise are in disagreement with the expected ozone recovery. These results have implications for both reconciling theory and observed changes in the stratospheric circulation, as well as better understanding the rate of stratospheric ozone recovery.