It appeared in 1973, seemingly from anywhere: a hole in sea ice off the coast of Antarctica. But this was no ordinary hole. It was so large that it could swallow California.
For the following three winters the place of mystical opening remained. It then largely disappeared before re-emerging in 2017, with the size of a giant meow.
Sometimes this giant hole with an appetite the size of the state is called a polyenia – an area of open water that is surrounded by sea ice, unlike an iceberg.
But the mysterious Waddell Polynesia – occurring above the sea plateau of Maud Rise in the waters of the Waddell Sea in the Southern Ocean – is an extreme example of this environmental phenomenon. Why it opens dramatically and still surprises scientists for so long.
Last year, researchers suggested that opening up to such abandonment required the coincidence of a series of climatic anomalies coming together at the same time for Waddell Polynesia.
Another 2019 study, led by atmospheric scientist Diana Francis, proposed what such anomaly was: scars from severe cyclones generated by atmospheric circulation that could pull floating sea ice in opposite directions and create giant openings. can do .
Francis, a senior scientist at the UAE’s Khalifa University, has just led a new study that sheds light on another, contributor to the event that has hitherto been overlooked: atmospheric rivers of warm, moist air.
In new research, Francis and his team analyzed atmospheric data dating back to the 1970s, and found that these ‘rivers in the sky’ played an “important role” in the creation of the 1973 and 2017 Waddell Polynesia events, Strong, steady flow in the days preceding both events is evident.
“I was surprised to see almost instant melting in sea ice covered by atmospheric rivers during the coldest months of the year in Antarctica,” Francis told Nature Middle East.
Researchers say atmospheric circulation carried a belt of warm, moist air from the coast of South America to the polar region, which induces melting through a combination of effects, including: the release of heat into the air mass; A local greenhouse effect created by water vapor; And contribute to cyclone dynamics.
“Atmospheric rivers make storms more intense because they provide more water vapor. They are interconnected, not independent,” Francis explained New scientist.
Weddell gives rise to Polinia’s monumental meltdown, which is unlikely to be the last word, but new insights broaden our understanding of how giant holes are made.
Given both atmospheric rivers and cyclones are predicted to increase in severity with global warming, this strange opening on the coast of Antarctica is something we can see more often, but we’ll have to wait and see.
The findings are stated in Science advance.