Most people are familiar with the seasonal ozone hole over Antarctica, forming each year during autumn. Scientists have monitored this hole since the 1980s when its emergence sparked a global effort to reduce the use of chemicals, including some aerosol products, that contribute to the hole.
The Antarctica ozone hole also led to the creation of the 1987 Montreal Protocol – designed to protect the stratospheric ozone layer by reducing the production and use of ozone-depleting substances called CFCs in order to protect the Earth.
The ozone layer is a natural, protective layer of gas in the stratosphere that shields life from the Sun’s harmful ultraviolet radiation. NASA likens the ozone layer to an atmospheric sunscreen. It actually helps to keep our planet habitable – so holes in this layer are not wanted.
The new “mini-hole” over the Arctic
For the past several weeks, scientists from the German Aerospace Center (DLR) have noticed and been following the unusually strong depletion of ozone over the northern polar regions. Using data from the Tropomi instrument onboard the Copernicus Sentinel-5P satellite, – which measures spectral bands in the UV, VIS, NIR, and SWIR – scientists were able to watch the formation of the hole in the atmosphere.
In the past, according to Phys.org, mini ozone holes have occasionally been spotted over the North Pole, but the depletion over the Arctic this year is unusual because it is much larger compared to previous years.
Diego Loyola, from the German Aerospace Center, comments, “The ozone hole we observe over the Arctic this year has a maximum extension of less than 1 million sq km. This is small compared to the Antarctic hole, which can reach a size of around 20 to 25 million sq km with a normal duration of around 3 to 4 months.”
Significantly, unusual atmospheric conditions, including freezing temperatures in the stratosphere have caused the loss of ozone this year. The extremely cold temperatures (below -80°C), sunlight, wind fields and substances such as chlorofluorocarbons (CFCs) all played a role.
Diego says, “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. We expect the hole to close again during mid-April 2020.”
Claus Zehner, ESA’s Copernicus Sentinel-5P mission manager, adds, “The Tropomi total ozone measurements are extending Europe’s capability of the continuous global ozone monitoring from space since 1995. In this time, we have not witnessed an ozone hole formation of this size over the Arctic.”
