Arctic Ozone Amplifies Stratospheric Circulation Extremes

Abstract Stratospheric ozone has long been suspected to drive interactions involving chemistry, radiation, and the circulation. However, the significance of these interactions, the underlying mechanisms, and the specific conditions that facilitate them remain poorly understood. In this study, we use a dry dynamical-core model with a simplified linear ozone scheme and a shortwave radiation parameterization to investigate these interactions. Our analysis, based on two long control simulations with either interactive or prescribed ozone, reveals that interactive ozone increases the persistence and interannual variability of the stratospheric circulation during northern spring, a period with sufficient solar radiation over the northern polar cap. This effect is closely linked to late-winter extreme stratospheric circulation events, such as stratospheric sudden warmings (SSWs) and vortex intensifications (VIs). While interactive ozone does not alter the frequency of these events, the ozone perturbations induced by the circulation amplify the associated temperature and wind anomalies. Specifically, late-winter VIs are followed by a colder and more persistent polar vortex in spring when interactive ozone is used, compared to fixed ozone. This results in a 5-day delay in the breakdown date of the vortex and a more positive North Atlantic Oscillation at the surface. Although interactive ozone also amplifies perturbations following SSWs, these effects are less pronounced than those observed for VIs. Our findings contribute to a growing body of evidence highlighting the importance of ozone–dynamics interactions for simulating the stratospheric circulation, its variability, and its surface impacts.