“This is a ground-breaking study that uses cutting-edge underwater technology to investigate a critical region of Antarctica in unprecedented detail,” said British Antarctic Survey Physics, which was not involved in the study. says oceanographer Peter Davis. “Never before have we been able to observe ice-sea interactions occurring within basal crevasses on Antarctic ice shelf grounding lines at such fine spatial scales.”
Icefin discovered that ocean currents move water through crevasses, but the mechanics within the crevasse create water. more movement. Since the height of the crevasse is 50 meters, the pressure at the top is lower than at the bottom of the opening. The freezing point of seawater decreases as you get deeper into the ocean, and ice melts more easily as you go deeper into the ocean. As a result, the seawater in this crevasse is frozen at the top, but melting at the opening.
Thawing and freezing cycles cause water to move. When the ice melts, fresh water is produced, and because it is less dense than seawater, it rises to the top of the crevasse. But when seawater freezes at the top, it releases salt, which causes downwells. So this creates churn. “Within just 50 meters of terrain, thaw-induced flotation and freezing-induced subsidence occur,” Washam says.
This is where the surface shape of the ice really matters. If the ice is flat, a protective layer of cold water can build up. “This barrier forms between the relatively warm ocean and the cold ice,” says Alexander Lovell, the institute’s director. ice and climate group He studies Antarctic glaciers at Georgia Tech, but is not involved in the research. If ice doesn’t mix with warm water, it won’t melt easily. “It’s just sitting there,” he says.
But as Icefin has shown, the underside of an ice shelf can have a golf-ball-like depression. “The rougher the interface, the more likely there will be turbulence as water flows over it, and that turbulence mixes the water,” says Lovell. This jagged terrain can melt faster than the flat part of the ice shelf’s belly.
This dynamic is not well represented in models of melting Antarctic glaciers, and could be why they are melting faster than scientists predicted, Lovell said. “There have been various ideas about the cause of this difference, but by actually observing the ground truth from actual glaciers, we can determine that “this idea is correct and this idea is incorrect.” Please help us improve these models,” says Lovell. This is to explain what is already happening and to predict future changes.
