When you hear the term “dragon-skin,” ice no-one would blame you if you instantly thought of the Game of Thrones series; however, this is a real phenomenon. Recently, a team of Antarctic scientists observed the bizarre and rare scaly ice in the Ross Sea, known as “dragon-skin.”
It’s autumn in Antarctica, and while most South Pole expeditions have departed, the U.S. icebreaker research vessel Nathaniel B. Palmer continued to plow toward the heart of an Antarctic polynya.
Polynyas are areas of open water against Antarctica that are “ice factories,” with 10 times the average amount of sea ice produced due to the strength of local “katabatic” winds that flow from the interior of Antarctica.
Twenty-seven scientists from eight countries who are studying the winter behavior of coastal polynyas were given the chance to see the “dragon-skin” ice, which proved to be an early highlight. IMAS researcher Dr. Guy Williams said in a statement:
“Dragon-skin ice is very rare, bizarre evidence of a darker chaos in the cryospheric realm, not seen in Antarctica since 2007.
“Imagine your standard ice cube tray, filled once. After a week, you get one tray of ice cubes. But if you empty and re-fill the tray each night, you get so much more.
“That is what the katabatic winds are doing in the polynya, removing the ice, exposing the water and making more ice form.”
Dr. Williams said enhanced sea ice growth has a vitally important effect on the local and global oceanography. Seawater essentially freezes as freshwater ice, with the salty brine being rejected during the formation of the ice.
This makes the underlying water very cold and dense, enough to ultimately sink to the abyssal layer of the major ocean basins. This then kick-starts the southern limb of the global overturning circulation.
“We are currently at ground zero of a hurricane-strength (65+ knots) katabatic wind event in the Terra Nova Bay polynya, in the Ross Sea, West Antarctica. It’s quite incredible to experience such an epic demonstration of polar ocean-atmospheric interaction.
“After a couple of weeks of work in the advancing sea ice pack to the north, we have found ourselves once again strapping everything down as the winds and waves buffet our progress.
“We will spend the next two weeks taking advantage of quiet periods when the katabatic winds drop off to observe the increase in salinity of the shelf waters below polynyas as brine-rejected during sea-ice formation rains down to depths below 3,280 feet (1000 m) in the Drygalski Trough.”
Although dragon-skin ice is a rare sight, it may simply be because people are not in Antarctica during the winter often enough to see it.
Even though dragon-skin ice may be the natural result of physics, it certainly reminds us that even the most distant corners of our planet can be filled with otherworldly beauty.
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