The vast icy ocean current that circles around Antarctica is so huge that it carries 100 times more water than all the world's rivers combined, yet its influence on the world's climate is barely understood.
But now, with concern growing about the impact of global climate change, a new international research project aims to use the awesome powers of supercomputers to quickly fill that black hole in our knowledge of the world's largest ocean current.
The joint French-Australian study should make climate-change predictions more accurate but it could also improve weather forecasting in Australia, which feels the chilly influence of its polar neighbour in winter particularly.
"When it comes to the Southern Ocean, we're still 10 to 15 years behind what is known about the North Atlantic and North Pacific oceans," says Professor Matthew England, a UNSW oceanographer.
"The Antarctic Circumpolar Current is the world's largest ocean current but there's still a huge uncertainty about its influence on global climate. We hope to close that gap within the next five years."
Professor England, an Australian Research Council Federation Fellow with the UNSW School of Mathematics, is working on the project with Dr Ann Marie Treguier, from Laboratoire de Physique des Oceans and Dr Steve Rintoul from CSIRO marine and atmospheric research.
Together they are testing ocean-modelling software that gives an unprecedented ability to analyse and model currents on a five-kilometre grid of the ocean.
"Global warming, rising salinity, soil loss, loss of habitat and drought are just some of the environmental challenges facing Australia in the next fifty years," Professor England says.
"This work is crucial because our ability to forecast the effects of climate change will depend on having reliable climate prediction systems.
"We urgently need solid information about what influence this current is having and it's not feasible to physically sample and directly observe such a massive body of water at high resolution.
"It transports 130 million cubic metres of water every second and is a key part of the Southern Ocean that encircles Antarctica: it measures twice the area of mainland Australia, or 20 million square kilometres."
The team will use a computer model known as ORCA025 that can run 10 years of ocean modelling over a seven-day period on a powerful computer at the CNRS Computer Centre in France. http://www.cnrs.fr/index.html
"One of our goals is to understand how heat and salt get transported within and out of the Southern Ocean - which has direct implications for Australian climate. Our research will significantly improve our knowledge of the dynamics of the Southern Ocean, which has a major influence on global climate patterns.
"Dr Treguier's experience and unique ocean-modelling capabilities will bring new understanding of the Southern Ocean circulation, using one of the world's most powerful ocean models," Professor England says.
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