Auroras are responsible for punching holes in the ozone layer

A type of aurora briefly tore a 400 km wide hole in Earth's ozone layer
Ayesha Gulzar
Aurora borealis over ocean in Teriberka, Russia
Aurora borealis over ocean in Teriberka, Russia

dan-belistski/iStock 

An international team of researchers showed that a certain type of aurora called the "Isolated proton aurora" depletes our atmosphere's ozone layer. They discovered a nearly 250-mile-wide (400 kilometers) hole in the ozone layer right above where an aurora occurred. Before now, the influence of these particles was only vaguely known. The study is published in Scientific reports.

What causes the auroras?

Solar storms on the sun's surface give out huge clouds of electrically charged particles. These particles can travel millions of miles, and some may eventually collide with the Earth. Most of these particles are deflected away, but some become captured in the Earth's magnetic field. When they are entrapped, their charge ionizes the atmosphere and produces nitrogen oxides and hydrogen oxides. Both compounds contribute to ozone loss.

Auroras are responsible for punching holes in the ozone layer
Effects of EMIC wave-particle interactions at different altitudes

Although high-energy plasma particles damage the ozone layer, details of their impact are less well understood. This is because such particles are not visually observable, making it difficult to ascertain their location. However, when these charged particles interact with the upper atmosphere, they emit an isolated proton aurora that falls toward Earth. Typically, auroras appear as a belt around the north and south poles. However, these isolated proton auroras are visible as isolated spots or bands at lower latitudes.

"Isolated proton auroras can be observed by scientific all-sky cameras. Although it is a rather weak aurora, it is also visible to a regular person." explains team member Kazuo Shiokawa, a professor at the Institute for Space-Earth Environmental Research at Nagoya University.

Researchers investigated the ozone fluctuations below the isolated proton aurora to assess the impact of radiation-belt electrons. To detect electrons over the aurora, the team used a combination of satellite remote sensing, ground-based electromagnetic wave observations, and information from the International Space Station.

Does this mean that auroras are depleting the ozone layer?

The study found that isolated proton aurora caused a nearly 250-mile-wide (400 kilometers) hole in the ozone layer, right below where an aurora occurred. Comparing their results to simulations, the researchers found that the change was much more significant than predicted. Up to 10-60% of the ozone vanished within 90 minutes. Scientists were shocked by the immediacy and extent of the effects.

While auroras cause some damage to the ozone layer, it is important to note that the tear heals quickly and only occurs in the ozone layer in the mesosphere; the more critical layer below, the stratosphere, remains unaffected.

"This is the first observational study in the world to show that radiation belt electron fallout from space around the Earth has a direct, immediate, and localized effect on atmospheric changes in the mesosphere. This finding is expected to contribute to an improved prediction of short-term changes in the Earth's atmospheric environment by considering the effects of atmospheric ionization by high-energy plasma from space," the researchers said.

Researchers conclude that the finding can help in predicting changes in the Earth's atmospheric environment and fluctuations in space weather.

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