SOCCOM3: Science to Predict the Future of the Southern Ocean and its Global Impacts

The Southern Ocean plays a disproportionately large role, relative to its size, in Earth’s biogeochemical (BGC) cycles, responsible for ~40% of the annual global ocean uptake of anthropogenic CO2 from the atmosphere. Due to its important role in the carbon cycle and similarly important role in ocean heat uptake, the Southern Ocean exercises significant control on global climate. Recent hemispheric declines in sea ice and increased storms, warming, and precipitation signal major alterations in the Southern Ocean’s climate state. Understanding their impact on ocean carbon cycling is critical as declines in organic carbon production could transition the Southern Ocean from a global carbon sink to a carbon source. The Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project was launched in 2014 with a vision to transform our understanding of the Southern Ocean’s role in the carbon, heat and nutrient systems by combining innovative observations and advanced numerical modeling. An array of state-of-the-art BGC-Argo profiling floats has been deployed throughout the Southern Ocean, transforming it from the least to the best BGC-observed ocean basin. Using observations, assimilation of observations into models, and climate-scale modeling of carbon, nitrate, and oxygen cycling, SOCCOM3 will continue to produce fundamental new understanding of Southern Ocean biogeochemistry and physics, during this era of unprecedented change. SOCCOM has been in place long enough to produce significant advances in understanding Southern Ocean processes, but not long enough to discern the differences between natural climate variability and the anthropogenic trend. SOCCOM3 is capitalizing on this seminal system to enable understanding of these differences and translate this to improved climate prediction. The circumpolar BGC profiling float observations will be extended to 13 years of deployments through annual replenishments, including two new biological sensors to enhance study of changing ocean biomass, productivity, and carbon export. The lengthening record will allow researchers to track annual-to-interannual changes in pH, air-sea CO2 flux, and carbon inventories, and their linkage with physically and biologically driven processes. BGC state estimation will be extended to the Antarctic coast and to global coverage and will be used to test process-level understanding and provide initial conditions for future projections. Finally, the climate/BGC modeling component, including mesoscale-eddying coupled climate models and Earth System Models, will translate our growing understanding of the current ocean into a projection of the future, emphasizing the Southern Ocean’s two-way role in global climate. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.