Scientists solve mystery of Antarctic hole

Twice size of Wales The rare opening in the sea ice puzzled researchers when it occurred during the winters of 2016 and 2017

Scientists have solved the mystery behind the appearance of an Antarctic hole twice the size of Wales.

The rare opening in the sea ice puzzled researchers when it occurred during the winters of 2016 and 2017.

In winter 2017, the so-called Maud Rise polynya was especially large, growing from 9,500 square kilometers in mid-September to about 80,000 square kilometers by late October.

However, a study published Wednesday (1 May) in Science Advances reveals a key process that had eluded scientists as to how the opening was able to form and persist for several weeks.

The team of researchers from the University of Southampton, the University of Gothenburg and the University of California San Diego studied the Maud Rise polynya – named after the submerged mountain-like feature in the Weddell Sea, over which it grows.

They found the polynya was brought on by complex interactions between the wind, ocean currents, and the unique geography of the ocean floor, transporting heat and salt towards the surface.

In Antarctica, the surface of the ocean freezes over in the winter, with sea ice covering an area about twice the size of the continental United States.

In coastal areas, openings in the sea ice occur every year. Here, strong coastal winds blow off the continent and push the ice away, exposing the seawater below. It is much rarer for these polynyas to form in sea ice over the open ocean, hundreds of kilometres away from the coast where the seas are thousands of meters deep.

Aditya Narayanan, a Postdoctoral Research Fellow at the University of Southampton, who led the research, said: “The Maud Rise polynya was discovered in the 1970s when remote sensing satellites that can see sea ice over the Southern Ocean were first launched.”