Stratospheric Ozone Variability Linked to Dynamical Forcing in the Arctic Winter 2023/2024

This paper investigates the seasonal and daily responses of the zonal‑mean O₃ mass‑mixing ratio to polar‑vortex disturbances during the boreal winter of 2023/2024, using MERRA‑2 data for the period 1 October 2023–30 April 2024. In addition to the expected latitudinal coupling during SSW events, the seasonal ozone field exhibited a pronounced zonally asymmetric distribution, referred to as the zonally asymmetric ozone oscillation (ZAOO), most evident in the lower stratosphere throughout the winter months. The seasonal behaviour of the ozone tendency was also investigated. To provide a plausible explanation for the observed features, a combination of the Quasi-biennial oscillation (QBO), dynamical transport, and photochemical processes was considered. For the first time, TEM diagnostics were applied to individual winter seasons and specific SSW events, enabling detailed examination of ozone‑tendency variability across latitude and altitude. The results provide clear quantification of the dynamical and net chemical contributions to both the seasonal (October–April) and specific SSW event ozone tendencies. These findings support systematic assessments of each intriguing winter and SSW event, offering new opportunities to identify links between SSW type and the dominant mechanisms shaping the ozone‑tendency response.