Observation, quantification and simulation of the physical and biogeochemical processes that determine the Southern Ocean’s state and transient response to external forcing are critical to our prediction of ocean ecosystems and the global carbon cycle. Advances in innovative sensors, data collection, state estimation, modeling capabilities, artificial intelligence and machine learning, as well as the workforce development that has accompanied these advances, have finally established the necessary infrastructure to permit a deeper understanding of the Southern Ocean’s processes that are relevant to ocean ecosystem health and for reducing uncertainties in near-term projections. These advances, however, have highlighted inconsistencies, assumptions and contradictions in established theory and understanding. This session will present new results, new tools and new techniques based on modeling and/or observational efforts that investigate biogeochemical processes, large-scale and mesoscale circulation, mixing, ocean-atmosphere and ocean-ice interactions, as well as strive to identify existing inconsistencies and assumptions that need to be re-examined.