UV increase due to ozone loss
The chemical depletion of ozone in the stratosphere causes an increase of ultraviolet radiation on the ground. The UV index is a measure of the danger of the UV radiation. It corresponds to the sunburn-effective solar irradiance.
This is a sample calculation [1], how the UV index typically changes at a certain latitude in winter and spring. Shown are noontime values of the UV index at clear sky for the range of the observed ozone columns of the years 2000 and 2012 (black) and corresponding values for a given decrease the ozone column (blue). The selection of the two values for geographical latitude and ozone loss can be altered. The anthropogenically induced polar ozone depletion takes place within the polar vortex, which in winter and spring is well separated from the mid-latitudes. After the breakdown of the polar vortex (in the Northern hemisphere typically at the latest in early April), ozone-rich air from mid-latitudes will be transported back into the polar regions.
In contrast to the Southern hemisphere, there are typically no significant increases to very high UV indices in polar high latitudes in the Northern hemisphere in the relevant period until April.
These graphs show how the maximum UV index (at noontime at clear sky) would change due to ozone depletion in the Arctic polar vortex.
| [1] | The mean values and standard deviations of the ozone columns were calculated from the database of Bodeker-Scientific (http://www.bodekerscientific.com). Calculation of the UV index for cloudless sky according to the method of Allaart et al. (Meteorological Applications, 11, 59-65, 2004) |
The table below gives an indication of the importance of the different UV indices:
| UV-Index | Evaluation | Protection |
|---|---|---|
| 0 – 2 | low | No protection required |
| 3 – 5 | moderate | Protection required: hat, T-shirt, sunglasses, sunscreen |
| 6 – 7 | high | Protection required: hat, T-shirt, sunglasses, sunscreen |
| 8 – 10 | very high | additional protection required: avoid staying outside if possible |
| ≥ 11 | extreme | additional protection required: avoid staying outside if possible |
