updated: August 23, 2021 08:04 he is
Tokyo [Japan], Aug. 23 (ANI): The same phenomenon that causes auroras – the magical curtains of green light often visible from Earth’s polar regions – is causing the depletion of the ozone layer in the mesosphere. This depletion may have significance for global climate change, and thus understanding this phenomenon is important.
Now, a group of scientists led by Professor Yoshizumi Miyoshi of Nagoya University, Japan, has observed, analyzed and provided insights into this phenomenon. The results were published in Nature’s Scientific Reports.
In the Earth’s magnetosphere – the region of the magnetic field around the Earth – electrons from the Sun remain trapped. Interactions between electrons and plasma waves can cause trapped electrons to escape and enter Earth’s upper atmosphere (the thermosphere).
This phenomenon, called electron deposition, is responsible for the auroras. But recent studies show that this is also responsible for the depletion of the local ozone layer in the atmosphere (below the thermosphere) and may have a certain effect on our climate.
Moreover, this depletion of the ozone layer in the atmosphere can occur precisely during the aurora borealis. While scientists have studied electron deposition in relation to the auroras, none of them have been able to explain how it causes depletion of the ozone layer in the mesosphere.
Professor Miyoshi and his team took the opportunity to change this narrative during a mild geomagnetic storm over the Scandinavian Peninsula in 2017.
They were targeting their observations of “pulsating aurora” (PsA), a type of faint aurora. Their observations were made possible by coordinated experiments with the European Incoherent Radar (EISCAT) (at an altitude of 60 to 120 km where PsA occurs), the Japanese Arase spacecraft, and an all-sky camera network.
Arase data showed that the electrons trapped in the Earth’s magnetosphere have a wide energy range. She also noted the presence of chorus waves, a type of electromagnetic plasma waves, in that region of space.
Computer simulations then showed that Ares had observed plasma waves causing these electrons to be deposited across the wide energy range, which is consistent with EISCAT observations below the Earth’s thermosphere.
Analysis of the EISCAT data showed that electrons with a wide energy range, from a few keV (kiloelectronvolts) to MeV (megaelectronvolts), cause PsA. These electrons carry enough energy to penetrate our atmosphere for less than 100 km, up to an altitude of up to 60 km, where atmospheric ozone is located.
Indeed, computer simulations using EISCAT data have shown that these electrons immediately deplete local atmospheric ozone (by more than 10%) upon impact.
Explains Professor Miyoshi, “PsAs occur almost daily, spread over large areas, and last for hours. Therefore, the depletion of the ozone layer from these events may be significant.”
Speaking about the greater significance of these findings, Prof. Miyoshi continues: “This is just a case study. More statistical studies are needed to confirm the amount of ozone destruction that occurs in the middle atmosphere due to electron deposition. After all, the effect of this phenomenon on the climate can be affect modern life. (Ani)
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