Vertical structure of upper-stratospheric and mesospheric ozone during polar stratospheric warmings

Sudden Stratospheric Warmings (SSWs) provide a direct route for dynamical and chemical coupling between the troposphere, stratosphere, mesosphere and lower thermosphere (MLT), but the vertical structure and event-to-event diversity of the associated ozone response are still not well quantified. We examine five Northern Hemisphere warmings (2009, 2011, 2013, 2019, and 2025) using Aura/MLS and TIMED/SABER temperature and ozone observations together with ERA5 reanalysis. Polar-cap (≥70°N) time–height temperature and ozone diagnostics are used to track anomalies from the lower stratosphere to the upper mesosphere (down to 0.001 hPa).

Major midwinter SSWs followed by elevated stratopause (ES) formation (2009, 2013, 2019) exhibit the strongest vertically coherent response: pronounced mesospheric cooling and a strong enhancement of the secondary ozone maximum near 0.01–0.003 hPa (≈80–90 km), with ozone nearly doubling shortly after onset. In contrast, the April 2011 final warming and the March 2025 major–final event show only weak mesospheric anomalies. In the lower–middle stratosphere (100–10 hPa), ozone increases persist for weeks after onset, while ES-type events are followed later by marked upper-stratospheric ozone decreases (10–1 hPa), consistent with the descent of NOx-rich MLT air during post-SSW recovery. Agreement across MLS, SABER, and ERA5 indicates that these coupled signals are robust and that SSW morphology controls the vertical reach of stratosphere–MLT coupling. We additionally present preliminary diagnostics of the 2026 SSW to place this event in the same framework.