Variations of geomagnetic field modulate surface UV radiation during solar particle events

What is it about?

During solar particle events (SPEs), sporadic short bursts of high-energy particles strike the Earth’s atmosphere. Most contemporary SPEs are largely deflected by the Earth’s magnetic field. However, extreme SPEs are known to have occurred in the past, along with changes in geomagnetic field strength. In a new study, published in PNAS, BOKU scientist Pavle Arsenović and colleagues from other institutions investigate the impact of extreme SPEs on atmospheric chemistry and surface UV radiation under different geomagnetic field strengths. The results suggest that, within current geomagnetic conditions, an extreme SPE would increase nitrogen oxides concentrations in the polar stratosphere and mesosphere. These changes would lead to reductions in stratospheric ozone, and therefore to elevated harmful UV radiation at the Earth’s surface. While contemporary geomagnetic conditions would limit the ozone level reductions outside of the tropics for roughly a year, an extreme SPE during a period when the geomagnetic field is absent would severely deplete stratospheric ozone globally for several years.

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Photo by Javier Miranda on Unsplash

Photo by Javier Miranda on Unsplash

Why is it important?

Our study shows that an extreme SPE in the absence of the geomagnetic field would elevate ground-level UV radiation which could lead to significant solar-induced damaging impacts on DNA. The results suggest further that extreme SPEs could pose risks to human health and may have influenced evolutionary processes in the past.

Perspectives