Modeling ocean ventilation

A team of researchers that includes NCAR’s Synte Peacock and Frank Bryan has carried out the first-ever century-long global ocean simulations with high enough resolution to capture mesoscale eddies, using supercomputers at NCAR and Oak Ridge National Laboratory.

The model tracked chlorofluorocarbons (CFCs) and other chemical tracers that yield information about ocean ventilation, the process by which water is transferred downward from the ocean’s surface and circulated around the globe. The research shines light on the link between changes in concentrations of pollutants and climate change, as oceans play a critical role in Earth’s balance of heat, water, and chemicals such as carbon dioxide.

Most previous studies of CFC distributions using ocean models have been done using coarse resolutions (grid spacing greater than 100 kilometers, or 62 miles), due to limits on computational power. The team needed a model with a resolution on the order of kilometers to tens of kilometers to resolve features such as narrow currents and eddies. With the help of NCAR’s bluefire and Jaguar, a Cray supercomputer at Oak Ridge, the researchers were able to apply one of the most realistic, fine-scale global eddying models ever run, and the only one to simulate such a large set of tracer distributions.

CFCs, which become inert (non-reactive) once in the water, are an ideal tool for tracing ocean ventilation, and they also help test the accuracy of circulation models. Understanding the process of ocean ventilation will help scientists project the oceanic uptake and redistribution of all atmospheric gases, including anthropogenic carbon dioxide. “This will ultimately increase our understanding of the role that oceanic activity plays in climate change,” Synte says.

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