What drives the deep
Professor Nathan Bindoff and his team at the University of Tasmania are using Raijin to investigate how the Southern ocean drives the Earth’s climate systems.
“The Earth’s poles are actually warmer than you would expect, and the equator is colder than you would expect, on the basis of the way the sun shines on the Earth,” says Professor Bindoff.
“This is because the oceans are circulating heat from the equator to the poles.”
Oceans are not just static bodies of water; constant movement and mixing in all directions results in a continuous shifting of energy, nutrients and heat.
These fine-scale motions have big impacts on the Earth’s climate equilibrium.
“In the atmosphere, we talk about highs and lows,” explains Professor Bindoff.
“The ocean has precisely the same thing occurring: weather systems that blow in blow out. We call these eddies. Eddies shift energy around in the water column and that energy balance is part of what sets the movement of heat from the equator to the poles.”
The team, including key researchers Max Nikurashin and Andreas Klocker is using complex 3D computer simulations to work out the different factors at play in eddy behaviour.
Their work, which is supported by three grants from the Australian Research Council, is informing multi-million dollar ship-based observational work.
“The only way we can do some aspects of ocean research is through computer simulation,” says Professor Bindoff.
“We are creating models to discover the role of different factors, such as ocean floor topography in the presence of really strong currents like the Antarctic Circumpolar Current.
“Using the results of these simulations, we have proposed observational experiments to go out and measure the same things to validate our models.
“So this is a great example of how theoretical simulations to some extent can drive observational science.”
The team’s simulations require millions of compute hours, hundreds of processes, and produce tens of terabytes of data – logistics that have only been made possible by recent advances in computational facilities such as NCI.
“Ten years ago you couldn’t have done this work,” says Professor Bindoff. “Now that computers are capable of these simulations, there’s been a renaissance in oceanography.
“The project’s results will guide the development of state-of-the-art global ocean and climate models and improve our ability to predict and respond more effectively to climate change.”