On the predictability of springtime ozone depletion events using the ECCC Global Deterministic Prediction System

• Main Authors: de Grandpre, J, Ivanova, I, Rochon, Y. J, Jouan, C, Vaillancourt, P. A
• Format: Journal Article
• Language: English
• Published: 15-10-2024
• Subjects: Physics - Atmospheric and Oceanic Physics
• DOI: 10.48550/arxiv.2410.11592

Ozone depletion events are recurring phenomena in both polar regions,
characterized by significant interannual variability. In this study, the
Environment and Climate Change Canada (ECCC) Global Deterministic Prediction
System is used to investigate the medium-range predictability of ozone and
weather throughout the anomalous polar ozone depletion events of 2020. The
system includes ozone assimilation and makes use of a prognostic ozone field
for the computation of heating rates. The ozone scheme uses simplified
photochemical modules to represent the impact of both gas-phase and
heterogeneous reactions throughout polar ozone depletion events. The study
shows that during the Boreal and Austral spring seasons, the predictability of
the total ozone column exceeds 10 days and is comparable to the predictability
of large-scale weather variables. It also demonstrates that over both polar
regions, the inclusion of ozone radiative coupling has a significant impact on
the temperature and wind distributions throughout the stratosphere. Over
Antarctica, the ozone coupled forecasts are systematically colder at all lead
times, which helps eliminate a temperature bias present in the model using
climatological ozone. The strength of the polar vortex also increases
significantly throughout the lower stratosphere, in better agreement with zonal
wind analyses. Over the Arctic the use of an ozone-interactive model also
produces significant changes in the temperature and wind forecasts, but the
impact on the quality of the weather forecasts is generally neutral. The study
shows the overall benefits of using ozone coupled models in the highly
perturbed springtime conditions of the polar regions.