Thirty years ago, the ozone hole was discovered which forms every winter and spring over the Antarctic continent. Meanwhile, the processes causing this ozone loss are well understood. Athropogenic emissions of chlorofluorocarbons (CFCs) did yield the release of chlorine compounds, which are able to catalytically destroy ozone. One important step in this mechanism is the so-called chlorine activation on stratospheric particles, a process that needs low temperatures below about -80 °C. One consequence of the ozone loss is the increase of UV radiation which enhances the risk of sunburn and skin cancer for humans, but also has consequences for other ecosystems.
The chlorine-catalyzed ozone loss also takes place in the Arctic spring, however, it is less developed in the northern hemisphere due to the generally warmer temperatures. Also, the Arctic ozone loss has a strong inter-annual variability. In the year 2011, stratospheric temperatures were very low, which caused the strongest Arctic ozone loss until present.
Within the project of the Earth System Knowledge Platform (ESKP), Forschungszentrum Jülich developed a web page, that does show the Arctic ozone loss of the current year in comparison with earlier years. In particular, the page shows:
- the determination of the atmospheric volume below a critical threshold temperature (VPSC), from which an estimate of the ozone loss can be determined
- Calculations of the ozone loss for the actual winter since November preformed by the Chemical Lagrangian Model of the Stratosphere (CLaMS), a model that was developed in Jülich
- the comparison of both these quantities with those from earlier winters
- a figure that illustrates the increase of UV radiation that would be caused by a certain ozone column loss to assess potential risks
For the winter 2014/2015, stratospheric temperatures were relatively warm, such that the ozone loss in this year is expected to be rather low. But in the actual winter (2015/2016) the temperatures are quite low. This has led to ozone depletion, that was never observed before in the Arctic. The depletion of ozone until the beginning of March amounts to over 100 DU. However, the UV index in middle Europe during that time is still quite low due to the low elevation of the sun. Caused by the the sudden stratospheric warming, the polar vortex starts to decay in early March. If remnants of the polar vortex are shifted towards mid-latitudes, the provided calculations could be used as an early warning system for possible increased UV exposures. These simulations can be accessed here.