The 600 keV electron injections in the Earth’s outer radiation belt: A statistical study

Tang, C. L.; Wang, Xu; Ni, Binbin; Su, Z.; Zhang, and JiChun

doi:10.26464/epp2022012

Cited by 5 publications

(8 citation statements)

References 58 publications

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“…The fastest possible increase of F ( E , t ) is still like E 2 (with a = 0), corresponding to a null gradient of PSD, ∂f ( p )/ ∂p = 0. But this would require injections of high energy E > 500 keV electrons, which are usually too rare and much too weak at L < 6.5 (Tang et al., 2022 ) to reach such a null PSD gradient. In the outer radiation belt, electron fluxes are initially steeply decreasing toward higher energy before chorus‐driven energization occurs during storm recovery (Murphy et al., 2018 ).…”

Section: Analytical Steady‐state Electron Distribution and Flux Due T...mentioning

confidence: 99%

“…In the Earth's outer radiation belt, the great variability of low‐energy (∼10–300 keV) electron injections and betatron acceleration during dipolarization events (Birn et al., 1998 , 2012 , 2014 ; Gkioulidou et al., 2015 ; Liu et al., 2016 ; Runov et al., 2015 ; Su et al., 2014 ; Tang et al., 2022 ; Turner et al., 2015 , 2016 ), and of the plasma and geomagnetic field conditions determining their subsequent acceleration to higher energy (O. V. Agapitov et al., 2019 ; Birn et al., 1997 ; Horne et al., 2005 ; Summers et al., 1998 ), are important obstacles to reliable predictions of full relativistic electron flux energy spectra during highly disturbed periods.…”

Section: Introductionmentioning

confidence: 99%

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Extreme Energy Spectra of Relativistic Electron Flux in the Outer Radiation Belt

et al. 2022

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Electron diffusion by whistler‐mode chorus waves is one of the key processes controlling the dynamics of relativistic electron fluxes in the Earth's radiation belts. It is responsible for the acceleration of sub‐relativistic electrons injected from the plasma sheet to relativistic energies as well as for their precipitation and loss into the atmosphere. Based on analytical estimates of chorus wave‐driven quasi‐linear electron energy and pitch‐angle diffusion rates, we provide analytical steady‐state solutions to the corresponding Fokker‐Planck equation for the relativistic electron distribution and flux. The impact on these steady‐state solutions of additional electromagnetic ion cyclotron waves, and of ultralow frequency waves are examined. Such steady‐state solutions correspond to hard energy spectra at 1–4 MeV, dangerous for satellite electronics, and represent attractors for the system dynamics in the presence of sufficiently strong driving by continuous injections of 10–300 keV electrons. Therefore, these analytical steady‐state solutions provide a simple means for estimating the most extreme electron energy spectra potentially encountered in the outer radiation belt, despite the great variability of injections and plasma conditions. These analytical steady‐state solutions are compared with numerical simulations based on the full Fokker‐Planck equation and with relativistic electron flux spectra measured by satellites during one extreme event and three strong events of high time‐integrated geomagnetic activity, demonstrating a good agreement.

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Section: Analytical Steady‐state Electron Distribution and Flux Due T...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Extreme Energy Spectra of Relativistic Electron Flux in the Outer Radiation Belt

et al. 2022

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“…Several other mechanisms can explain rapid enhancements of relativistic electrons in the Earth's outer radiation belt. Previous observations and simulations have shown that relativistic electron injections could lead to rapid enhancements of MeV electrons in the outer radiation belt, which were associated with the intense substorm electric fields or convection electric fields (e.g., Ganushkina et al., 2013; Ingraham et al., 2001; Kim et al., 2000; X. Li et al., 1998; Mithaiwala & Horton, 2005; Tang et al., 2022; Xiong et al., 2022). In addition, an interplanetary (IP) shock acceleration is also an important mechanism, which is caused by IP shock compressions on the dayside (e.g., Blake et al., 1992; Foster et al., 2015; Hudson et al., 2017; Kanekal et al., 2016; Schiller et al., 2016).…”

Section: Introductionmentioning

confidence: 99%

Rapid Enhancements of Relativistic Electrons in the Earth's Outer Radiation Belt Caused by the Intense Substorms: A Statistical Study

et al. 2023

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“…Noted that there were some small increases in the blue/black lines, which were caused by the local magnetic field increases or substorm electron injections (e.g., Tang, Zhang, et al, 2016;C. L. Tang et al, 2018C. L. Tang et al, , 2022.…”

Section: Data and Statistical Methodsmentioning

confidence: 99%

“…Some studies have also shown that substorm electron injections or enhanced convection can directly explain the rapid enhancements of relativistic electrons in the outer radiation belt (e.g., Dai et al., 2014, 2015; Ganushkina et al., 2013; H.‐J. Kim et al., 2021; X. Li et al., 1998; Su et al., 2014; Tang, Zhang, et al., 2016; Tang et al., 2022; S. Xiong et al., 2022).…”

Section: Introductionmentioning

confidence: 99%

The Evolutions of the Seed and Relativistic Electrons in the Earth's Outer Radiation Belt During the Geomagnetic Storms: A Statistical Study

Wang

Tang

et al. 2023

JGR Space Physics

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Using the Van Allen Probes data, we statistically study the evolutions of the seed and relativistic electrons in the Earth's outer radiation belt during the storms. Based on the different storm intensities and durations of the main phase, the storm events are divided into “moderate and short (MS) events,” “moderate and long (ML) events,” “strong and short (SS) events,” and “strong and long (SL) events.” The results from a superposed epoch analysis show that (a) For most MS and SS events, the seed electron fluxes can exceed pre‐storm levels, and enhanced fluxes mainly occur around the storm peak. (b) For the ML and SL events, the seed electron fluxes greatly exceed pre‐storm levels by more than an order of magnitude, and enhanced fluxes mainly occur during the main phase. (c) For most MS events, MeV electron fluxes are difficult to return to or exceed pre‐storm levels. While MeV electron fluxes at some L* shells for some SS events can exceed pre‐storm levels. (d) For most ML or SL events, MeV electron fluxes at L* ≥4.0 or ≥3.5 can exceed pre‐storm levels, and enhanced fluxes mainly start to occur from the main phase. These results suggest that the duration of the main phase and storm intensity play important roles in the evolutions of the seed and MeV electrons in the Earth's outer radiation belt during the storms. These are important for our further understanding of the electron dynamics of the outer radiation belt.

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The 600 keV electron injections in the Earth’s outer radiation belt: A statistical study

Cited by 5 publications

References 58 publications

Extreme Energy Spectra of Relativistic Electron Flux in the Outer Radiation Belt

Extreme Energy Spectra of Relativistic Electron Flux in the Outer Radiation Belt

Rapid Enhancements of Relativistic Electrons in the Earth's Outer Radiation Belt Caused by the Intense Substorms: A Statistical Study

The Evolutions of the Seed and Relativistic Electrons in the Earth's Outer Radiation Belt During the Geomagnetic Storms: A Statistical Study

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