"Many studies have looked at the effect of SPEs, or Carrington-like events, on the Earth’s current or past atmosphere," said Marco Calisto from the International Space Science Institute (ISSI) in Switzerland. "But the majority of these studies used only a 1D or 2D model and looked at past atmospheric chemistries. As the chemistry of our atmosphere changes, the effects of SPEs will change and so we decided to model the effects on the atmosphere in 2020, and use a 3D model to give a more complete picture."

As expected, Calisto and his colleagues found that the greatest effect was at the poles. They predicted an increase in mono-nitrogen oxides (NOx) and hydrogen oxide radicals (HOx) and a subsequent increase in nitric acid (HNO3) as well as a decrease in ozone in the polar mesosphere and the stratosphere. This causes cooling in the polar upper stratosphere with a resulting acceleration of the zonal winds and changes in the surface air temperature and total ozone.

But one result they did not expect was a large change in the surface air temperature as far away as Eastern Europe and Russia. "We were surprised to identify SPE-induced warming in Eastern Europe and Russia of up to 7 K for January," Calisto told environmentalresearchweb. "We expected to see a change, but were surprised at how large the increase in temperature is. This temperature increase is predicted to remain for a few weeks after the initial effect."

Calisto and his colleagues used the "Cosmic Ray-induced Cascade: Application for Cosmic Ray-induced Ionization" (CRAC:CRII) model, which was recently developed in Finland, for the atmospheric ionization, and then applied the event-based local model to force the Swiss-made global Chemistry Climate Model (CCM) SOCOL.

"The reason we found this temperature increase when other studies have not is that our model includes the transportation of ozone," explained Calisto. "We found more longevity in the increase in NOx and HOx and a longer decrease in ozone."

The results show an increase in NOx of up to 80 ppb in the northern polar region and an increase of up to 70 ppb in the southern polar region. HOx shows an increase of up to 4000%. Due to the NOx and HOx enhancements, ozone reduces by up to 60% in the mesosphere and by up to 20% in the stratosphere for several weeks after the start of the event.

The researchers now plan to look at how the Earth’s changing magnetic field will affect their observations. "Nowadays, the polar regions feel the direct effects of SPEs because the Earth’s magnetic field pushes the particles away at the equator," explained Calisto. "But as this field weakens, we need to model how this will change in the future."

Related links

Related stories