When a burst of solar energy hit Earth in June 2015, the resulting shower of particles blasted a 400-kilometre-wide hole in the upper ozone layer, new research has found.
Fortunately, the hole in the ozone layer only appeared in the Earth’s mesosphere – a high layer of the atmosphere that extends approximately 31 to 53 miles (50 to 85 km) above the Earth. – and did not extend to the much larger ozone layer in the stratosphere, which protects the Earth from harm ultraviolet (UV) found the researchers.
Yet ozone depletion in the mesosphere was far greater than researchers previously thought – and future events like this could alter climate patterns in the lower layers of the atmosphere, up to on Earth’s surface, the team wrote in their study.
In the new article, published on October 11 in the journal Scientific reports (opens in a new tab), the researchers analyzed a specific type of aurora known as the single-proton aurora. Unlike the aurora borealis which cause the famous northern Lights and their southern counterparts, isolated proton auroras are much smaller and fainter, appearing as isolated patches of green light rather than large, looping bands of color across the sky. These fainter auroras also occur at lower latitudes than the aurora borealis and southern auroras, which appear over the north and south poles respectively.
Isolated proton auroras occur when the sun spews out a barrage of fast-moving particles, which shoot through space, crash into Earth’s magnetosphere (the region around Earth dominated by the planet’s magnetic field), and surf in the lower levels of the atmosphere on magnetic field lines. In the mesosphere, these extraterrestrial particles charge local gas molecules, creating potentially dangerous compounds called nitrogen oxides and hydrogen oxides, researchers say.
Scientists already knew that these aurora-generated oxides could eat away ozone – a pale blue gas that occurs naturally in Earth’s atmosphere – but to what extent they never understood. So in the new study, a team of international researchers studied a single, isolated proton aurora that appeared above Earth on June 22, 2015. Using data from the International Space Station, along with various other detectors of Electromagnetic waves based on satellites and on the ground, the team measured the number of charged particles above the aurora and the amount of ozone that was depleted below.
The team found that an hour and a half after the aurora appeared, a hole almost as wide as the length of the Grand Canyon had opened up in the mesosphere’s ozone layer, directly below the aurora. . This was a much greater amount of ozone destruction than the team had predicted in the simulations – however, they added, the hole should heal naturally and not cause any long-term decline in ozone. ozone in the mesosphere.
Humans shouldn’t face an increased risk of UV damage from this hole, primarily because the auroras didn’t seem to affect the much larger ozone layer in Earth’s stratosphere (which sits about 9 to 18 miles, or 14.5 to 29 km, on the earth’s surface). This thin layer of gas is responsible for shielding the planet’s surface from most of the sun’s harmful UV rays, and has declining for three consecutive years largely due to human use of ozone-depleting chemicals. (Fortunately, long-term trends suggest this critical ozone layer is getting healthier).
But the discovery is still significant, because ozone depletion in the mesosphere is thought to be changing the climate in the lower levels of the atmosphere by ways that scientists don’t fully understand. According to the study authors, this research should help clarify these spillover effects.
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