Abstract
We considered basic mechanisms of atmospheric particle acceleration and estimated the escape rates of ionospheric ions (H + and O + ) during the geomagnetic field reversal. It is assumed that during the reversal the Earth's magnetic field deviates from the current dipole configuration, and the quadrupole component dominates. The standoff distance of the quadrupole magnetosphere is about of 3 Earth's radii and therefore a magnetic shielding protects the atmosphere from sputtering and ion pickup but not from the polar and auroral winds.
Highlights
The geomagnetic field is not stable and undergoes long-term changes
The field lines disturbed by the solar wind correspond to Voigt (1981) model of the dayside magnetosphere, whose magnetic field is Bp + Bcf + Bimf, where Bp is the intrinsic planet field, Bcf is the magnetic field of the Chapman-Ferraro current system and Bimf – interplanetary magnetic field (IMF)
We assume that the main sources of polar and auroral winds are solar illumination and solar wind energy, respectively
Summary
The geomagnetic field is not stable and undergoes long-term changes. Relatively long periods of evolutionary changes are followed by rapid geomagnetic reversals that last an average of the order of 250 000 years [Glassmeier et al, 2009]. The energy flux in these zones is typically reaching values 10 – 100 times higher than in the case with no magnetosphere It increases the ionospheric outflow of heavy ions (O+), but has little effect on the light ones (H+) [Brain et al, 2013]. The main escape processes consist of Jeans escape, photochemical escape and sputtering for neutral particles [Brain et al, 2016], and ion pickup and polar wind for charged particles. Fast-moving ions (of the solar wind or magnetosphere origin) can escape from a magnetic trap if they exchange charge with neutrals in the atmosphere (charge-exchange escape). If the intrinsic magnetic field is stronger than the induced one, it deflects the solar wind, thereby preventing ion pickup and sputtering, but contributes to the ions escape from the polar caps and cusps, i. According to Slapak et al [2017], only an insignificant part of the weakly accelerated H+ ions can be captured by the magnetic field and returned to the atmosphere
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