Ozone hole reaches its maximum extent
Scientists from the Copernicus Atmosphere Monitoring Service confirm that the ozone hole over the Antarctic is one of the largest and deepest in recent years. Analyses show that the hole has reached its maximum size.
The Copernicus Atmosphere Monitoring Service (CAMS), implemented by the European Centre for Medium-Range Weather Forecasts (ECMWF) on behalf of the European Commission, reports that as the ozone hole has reached its maximum extent. It is one of the largest and deepest in recent years.
Stratospheric ozone concentrations have been observed to have reduced to near-zero values over Antarctica around 20 to 25 km of altitude (50-100hPa), with the ozone layer depth coming just below 100 Dobson Units, about a third of its typical value outside of ozone hole events.
This is being driven by a strong, stable and cold polar vortex. CAMS scientists are seeing signs that the 2020 ozone hole now seems to have reached its maximum extent.
“There is much variability in how far ozone hole events develop each year. The 2020 ozone hole resembles the one from 2018, which also was a quite large hole, and is definitely in the upper part of the pack of the last fifteen years or so”, comments Vincent-Henri Peuch, Director of Copernicus Atmosphere Monitoring Service at ECMWF. “With the sunlight returning to the South Pole in the last weeks, we saw continued ozone depletion over the area. After the unusually small and short-lived ozone hole in 2019, which was driven by special meteorological conditions, we are registering a rather large one again this year, which confirms that we need to continue enforcing the Montreal Protocol banning emissions of ozone depleting chemicals.”
CAMS is contributing to the international efforts of preserving the ozone layer by continually monitoring and delivering high quality data about its current state. Computer models of the atmosphere are combined with measurements from satellites and in-situ stations to monitor closely the evolution of the phenomenon. As the stratospheric ozone layer acts as a shield, protecting from potentially harmful ultraviolet radiation, it is of the upmost importance to track its changes.
“CAMS is continuously monitoring the ozone layer to provide information on the extent and magnitude of the ozone hole each year as it develops and recovers”, adds Vincent-Henri Peuch. “We are providing forecasts of stratospheric ozone concentrations up to five days in advance. And, we also keep an eye on the amount of UV radiation reaching the Earth’s surface, which also depends on clouds and aerosols in the atmosphere.”
How the ozone hole is formed
Chlorine and bromine-containing substances accumulate within the polar vortex where they stay chemically inactive in the darkness. Temperatures in the vortex can fall to below -78 degrees Celsius and ice crystals in Polar stratospheric clouds can form, which play an important part in the chemical reactions.
As the sun rises over the pole, the sun’s energy releases chemically-active chlorine and bromine atoms in the vortex which rapidly destroy ozone molecules, causing the hole to form.