Simulating the Solar Wind‐Magnetosphere Interaction During the Matuyama‐Brunhes Paleomagnetic Reversal

Abstract

In the swmf-input folder,• The data provided in GaussCoeff.txt can be used to obtain the paleomagnetic intrinsic magnetic field during the inversion period through the spherical harmonic function.• The data provided in IMF_ideal.dat is used as the upstream solar wind input condition of SWMF.The mgt-3d-simu folder contains 3d magnetospheric simulation data at different times during the geomagnetic reversal.

Effects of Global Geomagnetic Field Variations Over the Past 100,000 Years on Cosmogenic Radionuclide Production Rates in the Earth's Atmosphere

“…During the periods of the dipole‐dominated geomagnetic field, the contribution of the quiet magnetosphere to the cutoff rigidities is small (Kudela & Usoskin, 2004; Nevalainen et al., 2013), but it may become significant during periods of a weak dipole field. Including the paleomagnetosphere in the cutoff rigidity calculation will affect the production through changes in the shielding against particles of cosmic (and solar) origin (e.g., Glassmeier & Vogt, 2010; Gong et al., 2022; Stadelmann et al., 2010). For space weather applications, cutoff rigidities at different altitudes are required, and scaling them assuming dipolar approximations introduces significant errors, especially during geomagnetic storm times (Kress et al., 2015).…”

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

“…Simulations are run for 100,000 steps to reach a steady state of the magnetosphere. Details of the model set can be found in our previous study (Gong et al., 2022).…”

“…Figures 1a and 1b, adopted from Gong et al. (2022), shows the intrinsic magnetic field component ( B r ) in geographic coordinates for the two chosen epochs. After the M‐B reversal at 765 ka, the geomagnetic field is more or less in a dipolar configuration.…”

“…Some other studies investigated the cut-off region of cosmic rays in more complex geomagnetic fields (Gao et al, 2022;Shea & Smart, 2004;Smart & Shea, 2009), but the detailed trajectories of the cosmic rays within the magnetosphere were not shown. Gong et al (2022) performed global MHD simulations to study the solar wind-magnetosphere interactions during the Matuyama-Brunhes (M-B) magnetic polarity reversal. They found that the magnetospheric configuration in the middle stage of the polarity reversal is quite irregular, neither like purely quadrupolar nor octupolar structure.…”

A new inclination-based method to evaluate the global geomagnetic configuration and axial dipole moment

“…The geomagnetic field not only blocks the entry of interstellar energetic particles that could damage the Earth's biosphere but also shapes the magnetosphere, which is an extension of the dipole field into space that slows the rate of atmospheric escape into interplanetary space (Wei Y et al, 2014;Tsareva et al, 2020). During a geomagnetic transition time, when the strength of the axial dipole (AD) decreases significantly, the interaction between the solar wind and the magnetosphere changes (Gao JW et al, 2022;Gong F et al, 2022), and the size of the magnetosphere shrinks, allowing energetic particles to reach the low latitudes of Earth (Vogt et al, 2007;Grießmeier et al, 2009;Stadelmann et al, 2010). Therefore, an adequate estimation of the configuration of the paleomagnetic field and the strength of the AD form the foundation for investigating the paleomagnetosphere.…”