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Abstract:
Under climate change, stratospheric ozone abundances will respond to temperature and circulation alterations, leading to chemistry-climate feedbacks and modulating the dynamical sensitivity, which are critical aspects in future climate projections. Results from previous studies show a significant inter-model discrepancy in climatic impacts of ozone changes under elevated CO2 levels. However, the many factors that are included and coupled in the ozone response make it difficult to distinguish the contribution of individual processes, therefore limit our understanding of the sources of uncertainty in the chemistry-climate feedback. This work aims to investigate the influence of CO2, and how its increased abundances will affect stratospheric ozone. We use SOlar Climate Ozone Links (SOCOL) v4.0, a climate-chemistry model with interactive chemistry and atmosphere-ocean dynamics to conduct Diagnostic, Evaluation and Characterization of Klima (DECK) experiments. In addition to coupled experiments, we also conduct offline radiative transfer modeling with Parallel Offline Radiative Transfer (PORT) to diagnose the radiative effects of ozone. Having more and updated models and larger range of equilibrium climate sensitivity compared to Coupled Model Intercomparison Project 5 (CMIP5), comparisons between CMIP6 model runs and previous SOCOL-MPIOM runs are conducted to better assess the inter-model discrepancy. This study further analyzes processes such as changes in the Brewer-Dobson circulation that may lead to the shift in global ozone distribution. We then look at potential drivers of these processes and quantify ozone climate feedbacks, along with their uncertainty across models. Finally, we evaluate the importance of interactive chemistry by comparing CMIP with interactive and non-interactive chemistry.
