University of Washington, Columbia University to use AUVs to study Antarctica's ice shelves
Researchers from the University of Washington (UW) and Columbia University are preparing to study Antarctica’s ice shelves from the ocean below, using battery-powered Seaglider AUVs.
According to GeekWire, the results of the study are expected to provide a better understanding of how ice retreats, and how climate change could “affect the loss of polar ice sheets and the resulting rise in sea levels.”
This study, which is being funded by billionaire philanthropist Paul Allen, could go a long way in proving that the devices from UW’s Applied Physics Laboratory (APL) are capable of doing this type of work.
During the week of Nov. 6, the APL team is performing what it is expecting to be its final round of testing for a fleet of three Seagliders, along with four profiling floats which are designed to provide detailed characterizations of the ocean-ice interface.
Within a few months, the AUVs will be deployed beneath one of West Antarctica’s ice shelves.
The deployment of the vehicles will take place from a South Korean icebreaking research vessel called the R/V Araon, and will be overseen by Jason Gobat of the University of Washington and Pierre Dutrieux of Columbia University’s Lamont-Doherty Earth Observatory. They will be deployed during a voyage that begins a week before Christmas.
The Seagliders have been designed to dive hundreds of yards into the sea to get beneath the ice. Previously, they have been used to study floating sea ice, but this will be the first time that they are used to navigate the “hazardous twists and turns” in underwater caves at the bottom of an Antarctic ice shelf.
As of right now, researchers do not know which ice shelf they will study, as they have to wait until the Korean Polar Research Institute’s icebreaker gets to Antarctica’s Amundsen Sea. Knut Christianson of the University of Washington says that because of its active dynamics, the Pine Island Glacier is preferred, but that area poses a risk because of the recent break-off of a huge iceberg, so observations on the scene will ultimately inform the research team’s decision.
When the Seagliders are deployed, they will be responsible for recording a variety of things, including readings for location and depth, water temperature, salinity and turbulence. Occasionally, the AUVs will return to the surface to relay their data back to UW using the Iridium satellite communications network.
As they study the physics of the receding polar ice shelves, the AUVs should be able to range as widely as 30 miles, thanks in large part to a network of acoustic navigation beacons.
Craig Lee, senior principal oceanographer at UW’s Applied Physics Laboratory, says that right now, researchers have a limited amount of data about the interface between polar ice and the underlying ocean.
Lee explains that “changes in polar ice sheets tend to be factored into climate models as parameters that merely approximate what will happen,” which leads to large margins of error in estimates for sea-level rise.
An example of this is nine years ago, when researchers from UW estimated that by the year 2100, water levels in Puget Sound could rise anywhere between 6 and 50 inches.
“If we can actually learn more about the processes, we can improve those parameterizations,” Lee says. “The hope is that by doing that, we narrow down the uncertainties and we get better predictions.”
According to researchers, there is a small chance that the Seagliders could be recovered a year after their deployment, but they are open about the likelihood of the AUVs not surviving their extended undersea mission. The AUVs and the floats cost about $100,000 and $30,000 each.
But the impact of this research is worth the cost, according to the research team, and Paul Allen’s team. In fact, Christianson says that just a few weeks’ worth of data “would be enough to advance the field of climate science.”
“If this mission is even slightly successful, the information could be very valuable,” Christianson adds.