Kiwi-led Antarctic HiPSMI project hoped to help with climate change understanding

A New Zealander-led project in Antarctica is pushing the boundaries of science and engineering thanks to a wheelie bin of ice and a swimming pool.

The team, funded by the Marsden Fund, has designed a cutting-edge device to measure the temperature of supercooled ocean water under sea ice.

The collaboration with Norwegian and US scientists has resulted in a High Precision Supercooling Measurement Instrument (HiPSMI) that's sent under the ice on the Icefin, a small, remotely-operated submersible robot to take temperature measurements.

But before getting to the ice of Antarctica, the team had to spend two weeks in isolation at a lodge in Methven.

While there they used the wheelie bin of ice and the lodge's pool to test HiPSMI, and made some technical improvements to it before their Antarctic excursion.

Sea ice usually freezes at -1.9 degrees Celsius, but not when fresh water flows beneath the ice shelf and mixes with the salty sea water, said Dr Inga Smith from the University of Otago.

"Then it becomes what's called supercooled, so it's still liquid but actually below the freezing point. It then snap freezes into crystals called frazil, they attach to the sea ice and form platelet ice," Smith said.

"We're really pushing the edge of polar engineering here, operating in these really cold temperatures and making high-precision measurements of that supercooling," she said.

The knowledge gained from accurate measurements of water temperature can help with both climate change modeling as well as weather prediction, said Maren Richter, a PhD student from the University of Otago.

The Icefin robot being examined by the team
Photo credit: Anthony Powell / Antarctic New Zealand

"We know more about the dark side of the moon than we know about what's going on underneath the Ross Ice Shelf," she said.

"These measurements help to inform understanding of how the system that is the ocean, the ice and the atmosphere works together, and how that all interconnects.

"These are all calculated by large scale models and the more accurate we can make these models, even on really small scales like this, the more accurate it will be on larger scales like informing weather in the future in New Zealand," she said.

Once the team got to Antarctica, they worked out of an ice camp on McMurdo Sound owned by NIWA.

Sarah Williamson, chief executive of Antarctica New Zealand, said the camp was key to the success of the team.

"They managed to collect oceanographic and sea ice data for 17 of the 20 days at the ice camp, and  HiPSMI data on eight of those days," she said.

"It's always satisfying when we can support this world-leading science so successfully in Antarctica, particularly when it has such important ramifications for the rest of the planet."