Empirical Loss Timescales of Slot Region Electrons due to Plasmaspheric Hiss Based on Van Allen Probes Observations

Zhu, Qi; Cao, Xing; Gu, Xudong; Ni, Binbin; Xiang, Zheng; Fu, Song; Summers, Danny; Hua, Man; Lou, Yunjiang; Ma, Xuebin; Guo, Yingjie; Guo, Deyu; Zhang, Wenxun

doi:10.1029/2020ja029057

Cited by 11 publications

(11 citation statements)

References 56 publications

(108 reference statements)

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“…(2021) further demonstrated that diffusion simulations of electron loss due to plasmaspheric hiss are sensitive to variability time scales, which revealed more diffusion from averaged diffusion coefficients calculated for individual observation‐specific diffusion coefficients than when the diffusion coefficients are constructed from averaged inputs. Nevertheless, constructing the diffusion coefficients using averaged inputs is still an important method that numerous studies relied on to reproduce the essential feature of the radiation belt electron dynamics (e.g., Claudepierre et al., 2020; D. Wang & Shprits, 2019; D. Wang et al., 2019; Horne et al., 2013; Hua et al., 2020; H. Zhu et al., 2019; L. T. Li et al., 2017; Q. Zhu et al., 2021). Therefore, understanding the effects of uncertainties in the key inputs of the radiation belt electron simulation is a prerequisite to improve the radiation belt model performance, confidence, and forecasting accuracy.…”

Section: Introductionmentioning

confidence: 99%

Ensemble Modeling of Radiation Belt Electron Acceleration by Chorus Waves: Dependence on Key Input Parameters

et al. 2023

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We perform ensemble simulations of radiation belt electron acceleration using the quasi‐linear approach during the storm on 9 October 2012, where chorus waves dominated electron acceleration at L = 5.2. Based on a superposed epoch analysis of 11 similar storms when both multi‐MeV electron flux enhancements and chorus wave activities were observed by Van Allen Probes, we use percentiles to sample the normalized input distributions for the four key inputs to estimate their relative perturbations. Using 11 points in each input parameter including chorus wave amplitude Bw, chorus wave peak frequency fm, background magnetic field B0, and electron density Ne, we ran 114 simulations to quantify the impact of uncertainties in the input parameters on the resulting simulated electron acceleration by chorus. By comparing the simulations to observations, our ensemble simulations reveal that inaccuracies in all four input parameters significantly affect the simulated electron acceleration, with the largest simulation errors attributed to the uncertainties in Bw, Ne, and fm. The simulation can deviate from the observations by four orders of magnitude, while members with largest probability density (smallest perturbations in the input) provide reasonable estimations of output fluxes with log accuracy errors concentrated between ∼−2.0 and 0.5. Quantifying the uncertainties in our study is a prerequisite for the validation of our radiation belt electron model and improvements of accurate electron flux predictions.

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Section: Introductionmentioning

confidence: 99%

Ensemble Modeling of Radiation Belt Electron Acceleration by Chorus Waves: Dependence on Key Input Parameters

et al. 2023

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“…Moreover, many previous studies (e.g., Ni et al, 2008Ni et al, , 2014Ni et al, , 2016Gu et al, 2012;Summers et al, 2007;Thorne et al, 2010Thorne et al, , 2013Zhao et al, 2019;Zhu et al, 2021) have demonstrated that the long-term wave-particle effect is dominated by hiss and chorus waves for sub-MeV electron dynamics. However, during the active geomagnetic periods, the scattering effect by multiple wave modes can be significant for radiation belt dynamics in terms of the short-time effect.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Combined Scattering of Concurrent Unusual High‐Frequency EMIC Waves and MS Waves on Radiation Belt Electrons

Zhou

et al. 2022

Geophysical Research Letters

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We report a concurrent event of unusual high‐frequency Electromagnetic ion cyclotron (EMIC) and Magnetosonic (MS) waves in correspondence with butterfly distributions for sub‐MeV electrons and flux decay of MeV electrons, observed by Van Allen Probe A on 16 October 2017. The scattering effects are quantitatively investigated by test particle simulations. The results indicate that the unusual EMIC waves mainly scatter electrons from hundreds of keV to several MeV at pitch angles <60° while the MS waves mainly influence sub‐MeV and MeV electrons at pitch angles >60°. Their combined scattering effects are suitably analyzed to be justified as the linear superposition of the effect induced by each wave mode. The Fokker‐Planck simulations exhibit the formation of butterfly pitch angle distributions for sub‐MeV electrons and the obvious flux decay for electrons ∼1.8 MeV at all pitch angles, showing similar variation trends to the observations. Our study suggests that the occurrence of the two waves can significantly influence the electrons over the whole pitch angle range, which can help us better understand the radiation belt dynamics.

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“…The empirical models of electron lifetime due to chorus wave or hiss wave pitch angle scattering are applied to determine the loss term 𝐴𝐴 − 𝑓𝑓 𝜏𝜏 (Gu et al, 2012;Zhu et al, 2021). Inside the empirical plasmapause location (Carpenter & Anderson, 1992), the electron lifetime is dominated by 𝐴𝐴 𝐴𝐴hiss obtained from the empirical model of slot region hiss induced electron loss timescales by Zhu et al (2021), while outside the plasmapause, we use the electron lifetime 𝐴𝐴 𝐴𝐴chorus parameterized by Gu et al (2012). The 4.5-hr resolution PSD derived from flux observation at the highest available L is used as the outer boundary condition for the 4.5-hr intervals, while a constant inner boundary condition is used at ∼1.1 𝐴𝐴 𝐴𝐴𝐸𝐸 .…”

Section: -D Modeling Of Radial Diffusion and Convectionmentioning

confidence: 99%

On the Energy‐Dependent Deep (L < 3.5) Penetration of Radiation Belt Electrons

Mei

Zhao

et al. 2023

Geophysical Research Letters

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Energetic electrons in the inner magnetosphere are normally trapped in two regions: the inner and outer radiation belts. The inner belt is relatively stable, while the outer belt is highly dynamic, with electron fluxes varying by orders of magnitude within days during geomagnetic storms. The slot region, usually devoid of energetic electrons, separates the two belts. During geomagnetically active times, outer belt electrons can extend to lower L (distance to the center of Earth in units of Earth radii in the equatorial plane) and even fill the slot region (Blake et al., 1992;Li et al., 1993). The dynamic variations of radiation belt particles are the result of a complex competition between acceleration, transport, and loss mechanisms. The most important source process for inner belt electrons is inward radial transport from the outer belt (Cunningham et al., 2018;Selesnick, 2016) with cosmic ray albedo neutron decay (CRAND) contributing at the inner edge of the inner belt (Li et al., 2017;Xiang et al., 2019;Zhang et al., 2019). The energy-dependence of outer belt electrons penetrating inward can help quantify the populations of electrons transported to the inner belt during a certain event, which is important for determining source and loss processes of inner electrons. This study will focus on the mechanism responsible for the energy-dependent penetration of outer belt electrons into the low L region (L < 3.5). Our study provides

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Empirical Loss Timescales of Slot Region Electrons due to Plasmaspheric Hiss Based on Van Allen Probes Observations

Abstract: Plasmaspheric hiss can be regarded as an incoherent, broadband electromagnetic whistler mode emission with frequencies ranging from ∼20 to ∼2 kHz (e.g.,

Cited by 11 publications

References 56 publications

Ensemble Modeling of Radiation Belt Electron Acceleration by Chorus Waves: Dependence on Key Input Parameters

Ensemble Modeling of Radiation Belt Electron Acceleration by Chorus Waves: Dependence on Key Input Parameters

Combined Scattering of Concurrent Unusual High‐Frequency EMIC Waves and MS Waves on Radiation Belt Electrons

On the Energy‐Dependent Deep (L < 3.5) Penetration of Radiation Belt Electrons

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