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Abstract The Southern Ocean (SO) plays a crucial role in the process of sequestering heat and carbon dioxide from the atmosphere and transferring them to the deep ocean. This process is intricately linked to the formation of Antarctic Intermediate Water (AAIW) and Subantarctic Mode Water (SAMW), which are pivotal components of the Meridional Overturning Circulation (MOC) and have a substantial impact on the global climate balance. AAIW and SAMW take shape in specific regions of the Southern Ocean due to the influence of strong winds, buoyancy fluxes, and their effects, such as convection, the development of thick mixed layers, and wind‐driven subduction. These water masses subsequently flow northward, contributing to the ventilation of the intermediate layers within the subtropical gyres. In this study, our focus lies on investigating the regional aspects of AAIW and SAMW transformation in CMIP6 models. We accomplish this by analyzing the relationship between the meridional transport of these water masses and air‐sea fluxes, particularly Ekman pumping, freshwater fluxes, and heat fluxes. Our findings reveal that the highest transformation rates occur in the Indian sector of the Southern Ocean, with notable values also observed in the southeast Pacific and south of Africa. Additionally, we assess the potential changes in these formation regions under future scenarios projected for the end of the 21st century. Although the patterns of formation regions remain consistent, there is a significant decrease in the transformation process. 

Abstract Subduction in the Antarctic circumpolar region of the Southern Ocean (SO) results in the formation of Antarctic Intermediate Water (AAIW) and Subantarctic Mode Water (SAMW). Theoretical understanding predicts that subduction rates of these waters masses is driven by wind stress curl and buoyancy fluxes. The objective of this work is to evaluate the extent to which AAIW and SAMW variability are correlated to SO air‐sea fluxes and how potential changes to those forcings would impact the future water mass export rates. We correlate the water mass volume transport at 30°S with Ekman pumping, freshwater and heat fluxes in the Coupled Model Intercomparison Project. The export of these water masses varies across models, with most overestimating the total transport. Correlation coefficients between the air‐sea fluxes and exports are consistent with theoretical expectations. In the picontrol/historical scenarios, the highest correlations with AAIW export variability are heat flux, while Ekman pumping best explains SAMW. However, multivariate regressions show that both AAIW and SAMW export variability are better explained using the combination of all three fluxes. In future scenario simulations air‐sea fluxes trend significantly in the catastrophic scenario (RCP8.5 and SSP8.5). Both AAIW and SAMW are still highly correlated to the fluxes, but with different correlation coefficients. The dominant forcing components even change from the present simulations to the future scenario runs. Thus, correlations between AAIW and SAMW transports and air‐sea fluxes are not stationary in time, limiting the predictive skill of statistical models and highlighting the importance of using complex climate models.