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posted by janrinok on Monday August 23 2021, @06:31PM   Printer-friendly

Under the northern lights: Mesospheric ozone layer depletion explained:

The same phenomenon that causes aurorae -- the magical curtains of green light often visible from the polar regions of the Earth -- causes mesospheric ozone layer depletion. This depletion could have significance for global climate change and therefore, understanding this phenomenon is important.

[...] In the Earth's magnetosphere -- the region of magnetic field around the Earth -- electrons from the sun remain trapped. Interactions between electrons and plasma waves can cause the trapped electrons to escape and enter the Earth's upper atmosphere (thermosphere). This phenomenon, called electron precipitation, is responsible for aurorae. But, recent studies show that this is also responsible for local ozone layer depletions in the mesosphere (lower than thermosphere) and may have a certain impact on our climate.

What's more, this ozone depletion at the mesosphere could be occurring specifically during aurorae. And while scientists have studied electron precipitation in relation to aurorae, none have been able to sufficiently elucidate how it causes mesospheric ozone depletion.

Prof. Miyoshi and team took the opportunity to change this narrative during a moderate geomagnetic storm over the Scandinavian Peninsula in 2017. They aimed their observations at "pulsating aurorae" (PsA), a type of faint aurora. Their observations were possible through coordinated experiments with the European Incoherent Scatter (EISCAT) radar (at an altitude between 60 and 120 km where the PsA occurs), the Japanese spacecraft Arase, and the all-sky camera network.

Arase data showed that the trapped electrons in the Earth's magnetosphere have a wide energy range. It also indicated the presence of chorus waves, a type of electromagnetic plasma wave, in that region of space. Computer simulations then showed that Arase had observed plasma waves causing precipitations of these electrons across the wide energy range, which is consistent with EISCAT observations down in the Earth's thermosphere.

Journal Reference:
Miyoshi, Y., Hosokawa, K., Kurita, S., et al. Penetration of MeV electrons into the mesosphere accompanying pulsating aurorae [open], Scientific Reports (DOI: 10.1038/s41598-021-92611-3)

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  • (Score: 0) by Anonymous Coward on Tuesday August 24 2021, @07:51PM

    by Anonymous Coward on Tuesday August 24 2021, @07:51PM (#1170486)