Icebreaker cyclone encounter reveals faster decline in sea ice – sciencedaily

In August 2016, a huge storm comparable to a Category 2 hurricane hit the Arctic Ocean. The cyclone resulted in the third lowest extent of sea ice on record. But what made the 2016 High Arctic Cyclone particularly appealing to scientists was the proximity of the Korean icebreaker Araon.

For the first time ever, scientists have been able to see exactly what happens to the ocean and sea ice when a cyclone hits. Researchers at the University of Alaska Fairbanks and their international colleagues recently published a new study showing that sea ice shrank 5.7 times faster than normal during the storm. They were also able to prove that the rapid decline was due to processes triggered by cyclones in the ocean.

“Usually when storms come they reduce the sea ice, but scientists haven’t figured out what really caused them,” said lead author Xiangdong Zhang of the International Arctic Research Center of the United States. ‘UAF.

There was general speculation that sea ice was declining only because of atmospheric processes melting ice from above. Zhang and his team proved this theory to be incomplete using “in situ” observations directly inside the cyclone. The measurements reflected things like air and ocean temperature, radiation, wind, and ocean currents.

It was a fluke for science, and perhaps a little scary for those on board, that the icebreaker was able to capture data from the cyclone. Usually ships try to avoid such storms, but Araon had just sailed in the middle of an area covered with ice and was locked in a pack ice.

Thanks to the ship’s position so close to the storm, Xiangdong and his team were able to explain that the loss of sea ice from cyclones is mainly due to two oceanic physical processes.

First, strong swirling winds force surface waters away from the cyclone. This draws warm water deeper to the surface. Despite this rising hot water, a small layer of cool water remains directly under the sea ice.

This is where a second process comes into play. The strong winds from the cyclone act like a mixer, mixing the surface water.

Together, rising warm water and surface turbulence heat the entire upper water column of the ocean and melt sea ice from below.

Although the August storm only raged for 10 days, the effects lasted.

“It’s not just the storm itself,” Zhang explained. “It has lingering effects due to the enhanced feedback from albedo ice.”

The storm’s enlarged open water patches absorb more heat, which melts more sea ice, causing even more open water. From August 13 to 22, the amount of sea ice in the entire Arctic Ocean declined by 230,000 square miles, an area more than double the size of the state of Arizona.

Xiangdong is currently working with a new computer model for the Ministry of Energy to assess whether climate change will cause more cyclones in the Arctic. Previous research shows that over the past half century, the number and intensity of cyclones in the Arctic has increased. Some of these storms, like the largest arctic cyclone on record in 2012, also resulted in record low sea ice extent.

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Material provided by University of Alaska Fairbanks. Note: Content can be changed for style and length.

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