Known as polynyas or semipermanent area of open water in sea ice, this Weddell polynya is quite mysterious in terms of its origin.
A giant hole as large as the state of ME has opened up in Antarctica's Weddell Sea for the second year in a row, confusing scientists due to its unusual characteristics. At 16,000 square miles, the 2017 Weddell polynya is roughly the size of Switzerland, and it's thought to be "driven by the upwelling of warm water, which releases heat to the air, before becoming cooler and denser, and sinking".
The cooling of the warmer ocean water when it reaches the surface may also have a broader impact on the ocean's temperature, but Moore says outside of local weather effects, scientists aren't sure what this polynya will mean for Antarctica's oceans and climate, and whether it is related to climate change.
Researchers said the event marks the second year in a row in which the polynya has formed, although it was not as large last year.
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The Southern Ocean has a fairly layered structure, and above the layer of warmer and salt water is a layer of cold and relatively fresh water. An enormous hole in the sea ice just opened up for no apparent reason, and researchers are at a loss as to why it might've happened.
For the first time, this polynya was discovered in 1974 by scientists from the Princeton Southern Hemisphere Climate Research Group.
NASA's Aqua satellite captured this image of a polynya off the coast of Antarctica, near Ross Island and McMurdo Station on November 16, 2011. Then it wasn't seen for four decades, reopened for a few weeks a year ago and has emerged yet again.
The hole first showed up on satellite images on September 9 and the researchers said it would be premature to blame the polynya on climate change. Then it reheats in deeper areas, allowing the cycle to continue.
At its largest extent, this winter's polynya had an area of open water close to 80,000 square kilometres (km2), he said.
However, the recently discovered polynya is "deep in the ice pack", which is rather unusual, Moore said.