Research reveals 43-year-old mystery in Antarctica

A study conducted by NYU research scientist Abu Dhabi (NYUAD), Diana Francis, elucidated the mystery that has lasted four decades around the occurrence of a polynya – an unfrozen ocean body appeared in a thick layer of ice during the Antarctic winter almost two years ago.

The Maud-Rise polynya was sighted in mid-September 2017 in the center of an ice floe in the Lazarev Sea in Antarctica, which led researchers to question the causes of this phenomenon during the coldest and winter months of the Antarctic, when the ice is at its thickest. Because of its difficult location of access, NYUAD scientists used a combination of satellite observations and reanalysis data to discover cyclones (as intense as category 11 on the scale Beaufort) and the violent winds they carry on the ice pack cause the ice to move in the opposite direction. directions, which leads to the opening of the polynya.

At the time of discovery, the Maud-Rise Polynya had an area of ​​about 9,500 square kilometers (the equivalent of the landmass of the state of Connecticut) and had grown more than 740% to 800,000 square kilometers in a month. Finally, the polynya merged with the ocean when the ice started to retreat in early austral summer. Before 2017, it was known that this phenomenon only occurred in the 1970s, when satellite observations began to be used more and more, and have since puzzled scientists.

"Once opened, the polynya works like a window through the sea ice, transferring huge amounts of energy in winter between the ocean and the atmosphere, "said Francis. Because of their large size, on the open sea polynyas are able to influence climate at the regional and global levels by changing ocean circulation. It is important for us to identify the triggers of their occurrence in order to improve their representation in the models and their effects on the climate.

"Given the link between polynya and cyclones we demonstrated in this study it is assumed that polynya events may become more frequent in a warmer climate as these areas will be more exposed to more intense cyclones. Previous studies have shown that under a warmer climate, the activity of polar cyclones would intensify and that extratropical cyclones would move to the Antarctic, which could reduce the extent of ice polynya closer to the cyclone formation zone, "she added.