Southern Ocean Circulation

This project will improve understanding of Southern Ocean change through a system of integrated observations, analysis and model simulations designed to detect, attribute and interpret change.

The circulation of the Southern Ocean strongly influences climate, sea level, biogeochemical cycles and biological productivity at both regional and global scales. Changes in the circulation of the Southern Ocean will therefore have large and widespread impacts. The magnitude of these impacts cannot be estimated by simply extrapolating present trends because of feedbacks that will alter the pace of change, possibly abruptly.  Such feedback mechanisms, with global consequences, include changes in the overturning circulation (the dominant mechanism responsible for ocean heat transport), a decrease in sea ice and a reduced ability of the Southern Ocean to sequester carbon.Sustained observations of the Southern Ocean circulation are critical to detecting and interpreting future change. ACE researchers and our partners will significantly add to Southern Ocean observing systems using ships, satellites, floats and moorings. These observations will for the first time provide multi-year measurements of the sinking of Antarctic Bottom Water which drives vertical circulation and deep mixing in the global ocean. ACE researchers will also sample beneath the sea ice and, through extensive international collaborations, document the evolution of the physical and biogeochemical state throughout the Southern Ocean at all depths.
Argo Float
These increased observations and process studies will improve numerical models of the Southern Ocean circulation; provide information on the response to and role of the ocean in climate change; and enable detection of any ongoing changes. Observations of change provide a particularly relevant and rigorous test for models:  if models can reproduce patterns of past change, we have more confidence in their ability to project the future.  New climate change detection and attribution methods will be applied to the Southern Ocean to determine the nature and causes of changes. In particular, we aim to distinguish between the effects of natural changes, the impacts of climate change caused by mankind’s emission of greenhouse gases and the effects of other human-induced changes such as ozone depletion. Knowledge of the evolving state of the Southern Ocean and attribution of the causes of observed changes will lead to an assessment of the sensitivity to future change. Improved understanding of key processes and their connection to lower latitudes and Australia will provide insight into the regional and global impacts of change in the Southern Ocean circulation and sea ice.

View: Dr Steve Rintoul discusses new technologies used to measure changes in the Southern Ocean

Projects and project leaders

Evolving State of the Southern Ocean: Dr Steve Rintoul

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