Rare, unusually large ozone hole develops over the Arctic-Canadian region


A huge area of sustained ozone depletion has developed over the Arctic-Canadian region — too late for the winter season, too early for spring, and unusually strong for the northern hemisphere.

The ozone layer is a natural layer of protective gas in the upper atmosphere that shields living things on Earth from harmful ultraviolet radiation from the Sun.

Under an ozone hole, this protective layer is gone, which may cause problems for living organisms as more of the harmful UV radiation penetrates.

“In the past days/weeks, we have been monitoring the onset of unusually strong ozone depletion over the north polar regions,” Severe Weather Europe (SWE) meteorologists noted.

“We already had a big drop in the minimum ozone values in late November 2019 and January 2020, due to [the] development of a ‘mini’ ozone hole over northern Europe.”

SWE said these small ozone holes over the North Pole do not develop because of a chemical destruction process, like over the Antarctic due to the aerosols.

False-color view of total ozone over the Arctic pole on March 16, 2020. The purple and blue colors are where there is the least ozone, and the yellows and reds are where there is more ozone. Credit: NASA/Goddard

Northern hemisphere ozone status November 1, 2020 – March 16, 2020

Northern hemisphere ozone status for the month of March — 1979 – 2019

A minimum ozone graph also shows two powerful low spikes in late November and January, but these were short-lived events that likely happens each year during the cold season.

“What really got our attention, was the overall reduction of ozone, in early March, when the values should actually be going up slowly,” said SWE.

“Something was off, and this time it was not just a quick low spike from a mini ozone hole, but a proper ozone destruction process.”


Image credit: P. Newman (NASA), E. Nash (SSAI), R. McPeters (NASA), S. Pawson (NASA)

SWE’s research showed that the ozone hole over the South pole develops due to a chemical process that tears the ozone– this process entails very cold air which is below -78 C (108.4 °F), sunlight, as well as human emissions of hazardous chloro-fluorocarbon (CFCs) and hydro-fluorocarbon (HFCs) aerosols.

Cold temperature lets stratospheric clouds to establish, and then sunlight reacts with the clouds to begin a photochemical process that breaks the ozone, resulting in the formation and growth of the ozone hole.

“As we mentioned, ozone destruction also needs sunlight, which is why this process is limited over the north pole,” SWE said.

“By late February and March when sunlight reaches the pole, the stratosphere over the north pole is usually not cold enough anymore to produce these clouds, which are essential for the ozone destruction process.”

The stratosphere can be unusually cold in some years, like this year, and it can generate stratospheric clouds at the same time that sunlight touches the pole, triggering ozone destruction.



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