Atmospheric losses of N⁺ and O⁺ under the extreme solar conditions during geomagnetic reversals

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 one, its shielding is still 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 the framework of a semi-empirical model. The results show that a weak geomagnetic field and strong solar activity lead to a change in the dominant escape mechanism and to significant atmospheric losses of preferentially lighter isotopes.