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What's wrong with these deep wounds in the Antarctic ice?



  In order to arrive at an answer, data had to be collected with floating sensors floating under the ice.
In order to arrive at an answer, data had to be collected with floating sensors floating under the ice. SOCCOM project / Hannah Zanowski

During the Australian winter, which extends from June to September the Antarctic is covered with nearly seven million square miles of ice. For several decades, scientists who view satellite imagery of these frozen swaths notice blue-black cavities in which water and ice open to the air and the sky. These jagged holes are known as Polynyas, and they can be huge ̵

1; in 2016 and 2017, the cuts in the Weddell Sea were more than 13,000 square miles wide . They also persist in the icy, windy darkness as temperatures drop relentlessly to -58 degrees Fahrenheit.

We still do not know much about these mines: for example, we are not sure yet how they affect the atmosphere – they may release carbon dioxide that has stagnated and stored in the deep ocean – and that's what it's unclear they mean to creatures that swim in them. (Analogs in the Arctic, for example, become food-rich oases.) In Antarctica, scientists are still arguing over an even more fundamental question: how the hell do these holes get there?

  This satellite image of Polynya near Maud Rise (center) was taken in September 2017.
This satellite image of Polynya near Maud Rise (center) was taken in September 2017. NASA Earth Observatory

To answer that, a team of researchers at the University of Washington led a creative approach that combined different perspectives, from deep diving to high-flying. The study, recently published in Nature was co-authored by researchers from the Scripps Institution of Oceanography and supported by satellite imagery, free-floating sensors, and a sea elephant brigade with head-strapped instruments. [19659009] The researchers had a happy break when some of the floating bodies used in the Southern Ocean's Carbon and Climate Observation and Modeling project appeared near Maud Rise, an underwater mountain where satellites have been in the last few years Years of polynya pictures. Looking more closely at the events in the water, the researchers concluded that Polynyas are "due to a combination of factors that need to occur simultaneously," says Ethan Campbell, a Ph.D. student in oceanography at the University of New York, Washington Main author of the study.

  This sea elephant with a small hat of instruments was extremely cute, but not as useful as the swimmer to actually gather data.
This sea elephant with a little hat made of instruments was extremely cute, but not as useful as the swimmer, to actually collect data. Courtesy of Dan Costa / University of California, Santa Cruz

The team found that warmer, saltier water is being pushed from deeper depths to the surface around the mountain. Then, when storms break in, a "deep, intense, vertical" mix begins, says Campbell, who continues to stir the water column. All of this triggers a pattern that repeats itself repeatedly, according to of the NASA Earth Observatory until the surrounding air warms up in the spring or the water gets brighter and fresher. The study takes up some aspects of earlier findings: as a recent study in which Maud-Rise-Polynya was attributed in 2017 to polar cyclones chewing ice, this team found that " Storms are essential, "Campbell adds.

Campbell and his associates discovered that it is all these elements that work together – winds and warm, salty water that flows to the surface and then cools and sinks into a constant turmoil – leading to Polynyas. "Several of these things could happen in a given year, but if you do not get them, you will not get Polynya," co-author Stephen Riser, an oceanographer at the University of Washington, said in a statement. [19659016] Scientific American reported that there is still much to be learned about what will happen to the holes as the climate continues to change – melting glaciers, for example, could add a supply of fresh water, potentially reducing the amount of water will probably migrate, but increasingly wild wind could exacerbate the flow. At least now, researchers are closer to understanding exactly how Polynyas originate in the Antarctic.


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