AGU's 2024 Annual Meeting (invited)

Recent studies reveal that stratospheric ozone’s response to increased CO2 tends to mitigate subsequent responses of several circulation features. For example, ozone changes dampen the acceleration of the stratosphere Brewer-Dobson Circulation (BDC) and invoke an equatorward shift of the tropospheric eddy-driven jet (EDJ). Although present in several modeling frameworks, the physical mechanisms for these results remain unclear. Further, it is not yet known how the interactive ozone impact compares in magnitude to the direct radiative CO2 forcing or surface warming. In this study, we design idealized simulations with the NASA Goddard Institute for Space Studies (GISS) E2.2 model in both a fully coupled and atmosphere-only configuration. The atmosphere-only configuration is used to decompose the full atmospheric response to CO2 into three components: the direct CO2 response, the response to sea surface temperature changes, and the response to the interactive ozone. This decomposition reveals that the ozone impact to mitigate an acceleration of the Brewer-Dobson Circulation is as large as the direct CO2 radiative response. In the troposphere, the ozone impact is limited to the Southern Hemisphere where its equatorward shift of the EDJ is slightly weaker than the direct radiative response’s poleward shift. The relevant processes connecting these ozone changes to the circulation response throughout the whole atmosphere are discussed.