Using data from the Tropomi instrument on ESA’s Copernicus Sentinel-5 Precursor satellite (also known as Sentinel-5P), a team of scientists from the German Aerospace Center (DLR) has noticed a strong reduction of ozone concentrations over the Arctic.
DLR researchers spotted an unusual ozone mini-hole over the Arctic. Image credit: DLR / BIRA / ESA.
The ozone layer is a natural, protective layer of gas in the stratosphere that shields life from the Sun’s harmful ultraviolet radiation, which is associated with skin cancer and cataracts, as well as other environmental issues.
The ‘ozone hole’ most commonly referenced is the hole over Antarctica, forming each year during autumn.
Small ozone holes have occasionally been spotted over the North Pole, but the depletion over the Arctic this year is much larger compared to previous years.
“The ozone hole we observe over the Arctic this year has a maximum extension of less than 1 million km2,” said Dr. Diego Loyola, a researcher at the DLR.
“This is small compared to the Antarctic hole, which can reach a size of around 20 to 25 million km2 with a normal duration of around 3 to 4 months.”
Even though both poles endure ozone losses during winter, the Arctic’s ozone depletion tends to be significantly less than Antarctica.
The ozone hole is driven by extremely cold temperatures (below minus 80 degrees Celsius), sunlight, wind fields and substances such as chlorofluorocarbons.
Arctic temperatures do not usually plummet as low as in Antarctica. However, this year, powerful winds flowing around the North Pole trapped cold air within what is known as the ‘polar vortex’ — a circling whirlpool of stratospheric winds.
By the end of the polar winter, the first sunlight over the North Pole initiated this unusually strong ozone depletion — causing the hole to form. However, its size is still small compared to what can usually be observed in the southern hemisphere.
“Since 14 March, the ozone columns over the Arctic have decreased to what is normally considered ozone hole levels, which are less than 220 Dobson Units,” Dr. Loyola said.
“We expect the hole to close again during mid-April 2020.”
“The Tropomi total ozone measurements are extending Europe’s capability of the continuous global ozone monitoring from space since 1995,” said Sentinel-5P mission manager Dr. Claus Zehner, of ESA.
“In this time, we have not witnessed an ozone hole formation of this size over the Arctic.”
