The geomagnetic storms that cause the Auroras - beautiful streaks of green light often visible from the Earth's polar regions - cause ozone depletion in the mesosphere. This depletion could have implications for global climate change, so understanding this phenomenon is essential.
Now a group of scientists led by Professor Yoshizumi Miyoshi from Nagoya University (Japan) has carried out observation, analysis and gave a deeper understanding of this phenomenon. The research results are published in the journal Nature's Scientific Reports.
In the Earth's magnetosphere - the region of the magnetic field around the Earth - electrons from the Sun remain trapped. The interaction between electrons and plasma waves can cause trapped electrons to escape and enter the Earth's upper atmosphere (thermosphere). This phenomenon, called electron precipitation, is responsible for the onset of the aurora. However, recent studies show that this phenomenon is also responsible for the local destruction of the ozone layer in the mesosphere (below the thermosphere) and may have some impact on our climate.
Moreover, this destruction of the ozone layer in the mesosphere can occur precisely during the aurora. And although scientists have studied electron precipitation in connection with auroras (auroras), none of them have been able to sufficiently figure out how they cause the destruction of mesospheric ozone.
Professor Miyoshi and his team seized the opportunity to change this view during a moderate geomagnetic storm over the Scandinavian Peninsula in 2017. Their observations were directed towards "pulsating aurors" (PSA), a type of weak auror. Their observations were made possible thanks to coordinated experiments with the European Incoherent Scatter Radar (EISCAT) (at an altitude of 60 to 120 km, where the PSA originates), the Japanese Arase spacecraft and a network of all-round cameras.
The Arase data showed that trapped electrons in the Earth's magnetosphere have a wide energy range. They also pointed to the presence of Horse waves in this area of space - a type of electromagnetic plasma waves. Computer simulations showed that Arace observed plasma waves causing the deposition of these electrons in a wide energy range, which is consistent with EISCAT observations in the Earth's thermosphere.
Analysis of the EISCAT data showed that electrons in a wide range of energies, from a few keV (keV) to MeV (megaelectronvolt), precipitate, causing PSA. These electrons have enough energy to penetrate our atmosphere to an altitude below 100 km, up to an altitude of ~ 60 km, where the mesospheric ozone is located. In fact, computer simulations using EISCAT data have shown that these electrons, when entering the mesosphere, immediately destroy local ozone (by more than 10%).
Prof Miyoshi explains: "PSA occur almost daily, spread over large areas and last for hours. Therefore, the ozone depletion from these events can be significant."
Talking about the greater significance of these results, Professor Miyoshi continues: “This is only a separate study. Further statistical studies are needed to confirm how much ozone destruction occurs in the middle atmosphere due to electron deposition. influence modern life ".