Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes

Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; He, Z. H.; Zhu, Hui; Zhang, Min; Shen, C.; Wang, Yuming; Wang, Shui; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Spence, Harlan E.; Reeves, G. D.; Funsten, H. O.; Blake, J. B.; Baker, D. N.

doi:10.1002/2013gl058912

Cited by 66 publications

(71 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Cyclotron resonant whistlermode-wave-electron interactions are an important controlling factor in radiation belt electron dynamics. Relativistic (∼ MeV) electrons can be generated in the outer radiation belt due to cyclotron resonance with chorus (Summers et al, 1998(Summers et al, , 2002(Summers et al, , 2007aRoth et al, 1999;Meredith et al, 2003;Summers and Omura, 2007;Xiao et al, 2010;Su et al, 2014). Chorus waves can pitch-angle scatter outer zone electrons into the loss cone and induce particle loss to the atmosphere (Lorentzen et al, 2001;O'Brien et al, 2004;Thorne et al, 2005;Summers et al, 2007a, b;Ni et al, 2008;Hikishima et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Effects of cold electron number density variation on whistler-mode wave growth

2014

View full text Add to dashboard Cite

Abstract. We examine how the growth of magnetospheric whistler-mode waves depends on the cold (background) electron number density N 0 . The analysis is carried out by varying the cold-plasma parameter a = (electron gyrofrequency) 2 /(electron plasma frequency) 2 which is proportional to 1/N 0 . For given values of the thermal anisotropy A T and the ratio N h /N 0 , where N h is the hot (energetic) electron number density, we find that, as N 0 decreases, the maximum values of the linear and nonlinear growth rates decrease and the threshold wave amplitude for nonlinear growth increases. Generally, as N 0 decreases, the region of (N h /N 0 , A T )-parameter space in which nonlinear wave growth can occur becomes more limited; that is, as N 0 decreases, the parameter region permitting nonlinear wave growth shifts to the top right of (N h /N 0 , A T ) space characterized by larger N h /N 0 values and larger A T values. The results have implications for choosing input parameters for full-scale particle simulations and also in the analysis of whistler-mode chorus data.

show abstract

Section: Introductionmentioning

confidence: 99%

Effects of cold electron number density variation on whistler-mode wave growth

2014

View full text Add to dashboard Cite

show abstract

“…Thus, geomagnetic storms and solar wind speed are not good predictors of energetic electron enhancement events, and electron response does not necessarily scale with the strength of a storm. Several recent studies during the Van Allen Probes era have in fact shown cases of strong outer belt relativistic electron enhancements during non-storm times Su et al 2014). Both papers noted the increase in chorus wave power during the acceleration periods, but did not explicitly make the connection to substorm activity.…”

Section: Role Of Substormsmentioning

confidence: 98%

Space Weather Effects in the Earth’s Radiation Belts

et al. 2017

Self Cite

View full text Add to dashboard Cite

The first major scientific discovery of the Space Age was that the Earth is enshrouded in toroids, or belts, of very high-energy magnetically trapped charged particles. Early observations of the radiation environment clearly indicated that the Van Allen belts could be delineated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. The energy distribution, spatial extent and particle species makeup of the Van Allen belts has been subsequently explored by several space missions. Recent observations by the NASA dual-spacecraft Van Allen Probes mission have revealed many novel properties of the radiation belts, especially for electrons at highly relativistic and ultra-relativistic kinetic energies. In this review we summarize the space weather impacts of the radiation belts. We demonstrate that many remarkable features of energetic particle changes are driven by strong solar and solar wind forcings. Recent comprehensive data show broadly and in many ways how high energy particles are accelerated, transported, and lost in the magnetosphere due to interplanetary shock wave interactions, coronal mass ejection impacts, and high-speed solar wind streams. We also discuss how radiation belt particles are intimately tied to other parts of the geospace system through atmosphere, ionosphere, and plasmasphere coupling. The new data have in many ways rewritten the textbooks about the radiation belts as a key space weather threat to human technological systems.

show abstract

“…The chorus emissions typically split into lower and upper bands with a gap around 0.5 f ce ( f ce is the equatorial electron gyrofrequency) [e.g., Tsurutani and Smith , ; Santolík et al , ]. The theoretical [ Horne and Thorne , ; Summers et al , ], observational [e.g., Horne et al , ; Meredith et al , ; Agapitov et al , ; Thorne et al , ; Mourenas et al , ; Su et al , ], and numerical [e.g., Summers et al , ; Li et al , ; Glauert and Horne , ; Shprits et al , ; Albert et al , ; Su et al , ; Mourenas et al , ; Glauert et al , ] works have revealed the importance of chorus‐driven local acceleration for the enhancement of radiation belt relativistic electrons on a timescale of days.…”

Section: Introductionmentioning

confidence: 99%

Quantifying the relative contributions of substorm injections and chorus waves to the rapid outward extension of electron radiation belt

Zhu

Xiao

et al. 2014

JGR Space Physics

Self Cite

View full text Add to dashboard Cite

We study the rapid outward extension of the electron radiation belt on a timescale of several hours during three events observed by Radiation Belt Storm Probes and Time History of Events and Macroscale Interactions during Substorms satellites and particularly quantify the contributions of substorm injections and chorus waves to the electron flux enhancement near the outer boundary of radiation belt. A comprehensive analysis including both observations and simulations is performed for the first event on 26 May 2013. The outer boundary of electron radiation belt moved from L = 5.5 to L > 6.07 over about 6 h, with up to 4 orders of magnitude enhancement in the 30 keV to 5 MeV electron fluxes at L = 6. The observations show that the substorm injection can cause 100% and 20% of the total subrelativistic (∼0.1 MeV) and relativistic (2–5 MeV) electron flux enhancements within a few minutes. The data‐driven simulation supports that the strong chorus waves can yield 60%–80% of the total energetic (0.2–5.0 MeV) electron flux enhancement within about 6 h. Some simple analyses are further given for the other two events on 2 and 29 June 2013, in which the contributions of substorm injections and chorus waves are shown to be qualitatively comparable to those for the first event. These results clearly illustrate the respective importance of substorm injections and chorus waves for the evolution of radiation belt electrons at different energies on a relatively short timescale.

show abstract

Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes

Cited by 66 publications

References 48 publications

Effects of cold electron number density variation on whistler-mode wave growth

Effects of cold electron number density variation on whistler-mode wave growth

Space Weather Effects in the Earth’s Radiation Belts

Quantifying the relative contributions of substorm injections and chorus waves to the rapid outward extension of electron radiation belt

Contact Info

Product

Resources

About