Lagged ENSO teleconnection mechanisms driving Antarctic stratospheric ozone depletion variability

The interaction between the El Niño-Southern Oscillation (ENSO) and Antarctic stratospheric ozone represents an important tropical-polar coupling mechanism. Using satellite-based observations, reanalysis datasets, and simulations from the global three-dimensional chemical-transport (TOMCAT) and chemistry-climate (WACCM) models, this study investigates how sea surface temperature anomalies (SSTA) associated with ENSO influence ozone variability. The results show that the peak phase of ENSO significantly impacts the interannual variability of Antarctic spring (September–October) stratospheric ozone in decaying years. Specifically, during the decaying year of El Niño (or La Niña), lower stratospheric ozone depletion is reduced (or enhanced) in Antarctic springtime. During the peak phase of El Niño, tropical SSTA intensifies convection and weakens upper tropospheric winds over the central and eastern equatorial Pacific, allowing more wave momentum fluxes from the troposphere into the stratosphere. In the decaying years, anomalous wave trains in both the troposphere and stratosphere link the tropical lower-atmospheric dynamics with the mid-high latitude stratospheric dynamics. Moreover, in the Southern Hemisphere under El Niño, the enhanced upward propagation of planetary waves accelerates the Brewer-Dobson circulation (BDC) and decelerates the mid-latitudes stratospheric zonal wind. Concurrently, polar stratospheric warming destabilizes the polar vortex in the decaying year, suppressing Antarctic springtime ozone depletion. In contrast, following La Niña, these coupling mechanisms typically reverse, leading to mid-latitude stratospheric zonal wind acceleration and polar stratospheric cooling, which strengthen the polar vortex and thus enhance ozone depletion. These findings advance understanding of ENSO-ozone teleconnections and inform ozone recovery predictions.