QUOCA – QUasibiennial oscillation and Ozone Chemistry interactions in the Atmosphere

It has long been recognized that radiative and dynamical feedbacks from stratospheric ozone can impact the Quasi-Biennial Oscillation (QBO). In other words, the changes in stratospheric ozone caused by QBO-driven changes in temperature and circulation alter the heating rates and overall QBO structure.  The ozone feedback on the QBO has been examined mainly in the context of recent historical climate (e.g., Butchart et al.; 2003, Shibata and Deushi; 2005, Shibata; 2021, Butchart et al.; 2023), but a review of this literature reveals large uncertainties in the magnitude – and even sign – of the ozone feedback on both the QBO period and amplitude.  One recent study has examined how ozone feedbacks on the QBO may change during rapid climate change, modeled as an abrupt quadrupling of atmospheric carbon dioxide concentrations (4 x CO₂) (DallaSanta et al.; 2021), but this topic remains relatively unexplored.  In general, methodological differences make it difficult to pinpoint and understand the drivers of conflicting conclusions drawn from previous studies.  The QUOCA working group addresses these issues by proposing a common set of chemistry climate models to assess the robustness of QBO-ozone feedbacks.