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*Polar watch* An ozone hole (mini) has formed over the North pole and Scandinavia! Ozone levels have dropped to over 50 Dobson units below normal.

The ozone hole that we usually talk about, can be found over the South pole. There, ozone is being destroyed in a man-powered chemical process every year. But, the North pole also has its own smaller version, called a “mini” ozone hole!

In case you are not familiar with this process, we encourage you to check out our coverage of the Antarctic ozone hole. There we talk about what is the ozone hole and why it forms in the first place.

Ozone is the protective layer that shields us from dangerous ultraviolet (UV) radiation. Under an ozone hole, that protective layer is gone, which can cause problems for living organisms, as more of the harmful solar UV radiation gets through. UV radiation is well-known to cause skin cancer in humans, if  one is frequently exposed. Below we see an example of the ozone hole over Antarctica in September 2000. Image is from the NASA ozone monitoring service. We usually look at the ozone values over the entire lower atmosphere. That shows precisely how much total protection is there between us and the Sun. We measure the ozone concentration in Dobson units.

The ozone hole over the South pole forms because of a chemical process that destroys ozone. That process includes very cold air (below -78°C), sunlight and is powered by human emissions of harmful chloro-fluorocarbon (CFC’s) and hydro-fluorocarbon (HFC’s) aerosols. Over the North pole, this process is much less intense due to the lack of required conditions, and is not nearly strong enough in most years to develop a large ozone hole, such as we see over the South pole. Instead, we still see smaller ozone holes forming from more natural causes, which are officially labeled as “mini” ozone holes. The latest analysis shows that such a “mini” ozone hole has developed over the polar circle into Northern Europe/Scandinavia and over northwest Russia. Images show the total ozone values in the entire atmosphere, where we can see low values over the regions. The second image is from NASA analysis on November 20th. The polar circle regions under this mini ozone hole are heading towards the polar night, where the Sun is at a very low angle, or does not rise at all. So this current event is not really harmful, but is very interesting from a scientific/educational standpoint.

The NCEP analysis on November 22 at 00UTC also revealed the mini ozone hole over the broader Scandinavian region. The animation below from NASA, shows the formation sequence of the ozone hole.

The anomaly plot that we did, shows ozone values quite below normal, in some places over 60 Dobson units (25%) lower than normal for this time of the year, compared to the 32-year ERA-5 records.

These “mini” ozone holes over the North pole do not form because of a chemical destruction process. Here the ozone is not destroyed, but just re-arranged/dispersed by specific weather circulation patterns. That dispersion reduces ozone concentrations over larger areas, creating a hole in the ozone layer, which can be just as harmful as its larger counterpart over the South pole. A mini ozone hole can last a few days to weeks, unlike the Antarctic ozone hole which lasts 3-4 months! But many indivisual mini ozone holes cam form over the North pole during the cold season from November to February. The image below from NASA, shows an example of formation and dissipation of a mini ozone hole in January 2012. Sudden stratospheric warming events and general polar vortex dynamics also play a very important role in the circulation and distribution of ozone across the Northern hemisphere.

We will keep you updated on any important further development. While you wait for more updates, make sure to check out our latest winter forecast: