On the Particle Motion in Paleo‐Magnetosphere During the Geomagnetic Polarity Reversal

Abstract

The Earth's intrinsic magnetic field is generated in the outer core and extends several Earth radii into space. The magnetosphere is formed after the geomagnetic field interacts with the solar wind, protecting the Earth from the Sun and high-energy particles from the cosmos Jackson & Finlay, 2007;Korte & Mandea, 2019). The current geomagnetic field can be approximated by a dipole centered at the Earth's core with an axis inclined by about 11° to the rotational axis. This dipole contributes approximately 80% of the surface magnetic field, with the remaining 20% being non-dipolar (Merrill et al., 1997). Consequently, charged particles can repetitively bounce and drift around the Earth, leading to trapped populations in the inner magnetosphere. For example, Van Allen radiation belts in the current magnetosphere are filled with high-energy charged particles (Hudson et al., 2008). The trapped energetic particles can also form ring current around the Earth, which distorts the background magnetic field and changes the plasma motion. The Earth's magnetic field is not static but rather constantly changing. Polarity reversals and shifts of the geomagnetic field have occurred many times in geological history (