Global Distribution of Reversed Energy Spectra of Ring Current Protons Based on Van Allen Probes Observations

Abstract

Energy spectra of ring current protons are crucial to understanding the ring current dynamics. Based on high‐quality Van Allen Probes RBSPICE measurements, we investigate the global distribution of the reversed proton energy spectra using the 2013–2019 RBSPICE data sets. The reversed proton energy spectra are characterized by the distinct flux minima around 50–100 keV and flux maxima around 200–400 keV. Our results show that the reversed proton energy spectrum is prevalent inside the plasmasphere, with the occurrence rates >90% at L ∼ 2–4 during geomagnetically quiet periods. Its occurrence also manifests a significant decrease trend with increasing L‐shell and enhanced geomagnetic activity. It is indicated that the substorm‐associated and/or convection processes are likely to lead to the disappearances of the reversed spectra. These results provide important clues for exploring the underlying physical mechanisms responsible for the formation and evolution of reversed proton energy spectra.

L‐Value and Energy Dependence of 0.1–50 keV O+, He+, and H+ Ions for CME and CIR Storms Over the Entire Van Allen Probes Era

“…Our results showed that the H + ion fluxes increased with increasing energies, consistent with the results reported by Yi et al. (2021), where they showed a global distribution of the proton energy spectra over 2013–2019 RBSPICE data set. They found that peculiar flux minima at low energy (50–100 keV) and flux maxima at higher energies (200–400 keV).…”

“…Our results show that the dynamics of the proton fluxes is highly energy dependent. This is consistent with the studies by Gkioulidou et al (2015) and Yi et al (2021). Gkioulidou et al (2016) studied the H + ion pressure evolution using Van Allen Probes data and found that the convection process is mainly responsible or the transport and acceleration of <80 keV H + ion, while the radial diffusion is more dominant for (>100 keV) H + ion.…”

Prediction of Dynamic Plasmapause Location Using a Neural Network

“…The plasmasphere, which is full of cold and dense plasma (electrons ∼1 eV with density ∼10 2 –10 4 cm −3 ), plays an important role in modulating the fluxes of energetic particles in the Earth's ring current and radiation belts (e.g., Cao et al., 2017; Darrouzet et al., 2009; Fu et al., 2020; Gu et al., 2011, 2012, 2020; Hua et al., 2019; Kozyra et al., 1995; Lemaire & Gringauz, 1998; Ni et al., 2013; Orr & Webb, 1975; Sandel et al., 2003; Takahashi & Anderson, 1992; Webb & Orr, 1975; Yi et al., 2021; Zhou et al., 2020). The plasmasphere strongly influences the plasma properties of the inner magnetosphere by wave‐particle interactions (e.g., Fu et al., 2016; Gary et al., 1994; Hua et al., 2020a; Ni et al., 2017, 2014; Thorne & Horne, 1992; Wilson et al., 1992; Xiang et al., 2018; Young et al., 1981), and contributes to assessing the low‐latitude boundary layer and plasma sheet (e.g., Cao et al., 2016; Elphic et al., 1997).…”