Shown here is the chemical ozone loss in northern winter as well its effects on mid latitudes in Europe. For example, in winter 2010/2011 there was a very high ozone depletion in the area of the Arctic polar vortex. In the frame of the Knowledge Platform "Earth and Environment" (ESKP) the effects this ozone loss at mid latitudes are explained and documented on a daily basis. An early warning system for such events is thus established. The basis is simulations with the Jülich chemical transport model CLaMS, which uses innovative transport and mixing algorithms to calculation of the exchange of air masses between polar and mid Latitudes (e.g. interference of low-ozone air in Europe). The realistic simulations are initialized by satellite observations and driven by ECMWF meteorological analyzes.
The ozone depletion in the polar vortex is determined by the temperature. For polar ozone loss, the temperature must drop below a threshold of approximately -78°C. For the Arctic winters of 2010-2020 the Calculations of ozone loss and Estimates from temperature are shown. To explain and assess the results, it is also explained how the UV increase on the ground develops in the course of spring for the case of different ozone losses. Calculated ozone loss and ozone column as well as the calculated from it maximum UV index (at noon with a clear sky) are considered Map display shown for the individual days.
Typically, the ozone columns in the Arctic are still higher than in the Antarctic despite ozone depletion, so that in the Arctic spring there is so far at most a moderate UV radiation at the ground.
The calculations for the current winter 2019/2020 show so far somewhat above average ozone depletion. Since the end of January the statospheric temperatures are very low and the polar vortex remains stable. End of February the average column ozone loss reached about 70 DU, the second highest value in the last decade after 2016. On 10 March the calculated average ozone loss was 95 DU, which corresponds to the maximum value for 2011, that was however only reached in late March. On 14 March, the value of 110 DU was exceeded thus the ozone loss this year is the highest of the years considered here.
Last winter 2018/2019 the stratospheric temperatures were too high for significant chlorine-catalyzed ozone depletion. A so-called "major warming" in early January led to the warming the stratosphere to split off a part of the polar vortex.
In recent years, Winter 2010/2011 and 2015/2016 were particularly noteworthy, as they were characterized by a cold, stable polar vortex, which with clear corresponding ozone depletion. This yielded only a slight increase in UV radiation, which is typically low in our latitudes in March. Extremely high UV values like in the Antarctic spring under the ozone hole did not occur so far in the Arctic.
The stratospheric temperatures in winter 2015/2016 were as low as never seen in recent decades before with the result of a very high ozone loss of over 100 DU. The lower ozone columns resulted in a slight increase in UV radiation on the ground. However, the UV radiation is in these latitudes is low at this time of year. When these air masses of the polar vortex moved towards mid-latitudes, the UV index in early March is as high as normally expected in late March. Extremely high UV values as in the Antarctic spring under the ozone hole did not yet occur in the Arctic.
The images below show the geographical distribution of the calculated ozone column (top) and ozone loss (bottom) for March 28, 2011. Shown is the total column between 12 and 22 km altitude in Dobson Units (DU).