Southern Ocean Overtuning Fingerprint Experiment

2026-07-22

The Southern Ocean overturning circulation exerts a powerful influence on Earth’s climate, and SOFIE is the first project seeking to detect and objectively measure the hydrographic fingerprint of changes in this overturning.The deep waters upwelling in the Southern Ocean account for up to half of the annual oceanic uptake of anthropogenic carbon from the atmosphere, dominate the global oceanic heat uptake with up to three quarters of the additional heat influx to the ocean occurring south of 30°S, and are a rich source of the nutrients that fertilise the majority of global ocean biological productivity north of 30°S.According to numerical studies, there is consensus that in response to increased westerly winds such as those occurring within contemporary climate change, variations in the overturning circulation are likely to be substantial.However, there is no established approach to provide observational evidence that these variations have occurred or are occurring in oceanographic measurements;and the lack of such an approach stems from the uncertain fingerprint of Southern Ocean overturning circulation changes on measurable oceanographic variables.Based on preliminary results supported by recent studies, SOFIE proposes that changes in the overturning circulation affect discernibly the ocean interior density structure from surface to depth across the Southern Ocean.We will rigorously test this hypothesis in the state-of-the-art numerical NEMO-OPA model, and assess in-situ evidence of overturning changes from the pan–Antarctic Argo network.To do this, SOFIE will combine model diagnostics of the Southern Ocean overturning circulation with the application to the model and in-situ fields of a novel algorithm characterising the vertical structure of the ocean.Given the ocean overturning’s sensitivity to changes in atmospheric forcing,SOFIE results will be a major step to constrain the changing ability of the Southern Ocean to slow down the rate of global climate change.

United Kingdom (UK)

2026-02-01