Atmospheric Losses of N+ and O+ under Extreme Solar Conditions during Geomagnetic Reversals

Cosmic Research. 2025. Vol. 63. P. 74–84.

Tsareva O. O., Cannell A., Levashov N. N., Malova H. V., V. Popov, Zelenyi L. M.

According to the widespread concept, the magnetosphere shields the planet’s atmosphere from
erosion caused by the solar wind. We have previously shown that during geomagnetic polarity reversals, when
the magnetic field weakens to about 10% of the present value, its shielding remains effective. This conclusion
was obtained for quiet periods of solar activity. However, since the duration of a geomagnetic reversal can
cover several thousand years, during which many extreme events can occur, changes in solar parameters such
as solar wind pressure and EUV flux should be considered. At high EUV flux, the concentrations of nitrogen
and oxygen, as well as their losses, increase in the Earth’s upper atmosphere. We have considered the most
significant mechanisms of heavy ion escape from Earth’s atmosphere and estimated their losses within a
semiempirical model. The results show that a weak geomagnetic field and strong solar activity lead to a
change in the dominant escape mechanism and significant atmospheric losses of comparatively lighter isotopes.

Keywords: geomagnetic reversal, ionospheric loss, Earth’s atmospheric escape