Van Allen Probes observation of plasmaspheric hiss modulated by injected energetic electrons

Abstract. Plasmaspheric hiss was observed by Van Allen Probe B in association with energetic electron injections in the outer plasmasphere. The energy of injected electrons coincides with the minimum resonant energy calculated for the observed hiss wave frequency. Interestingly, the variations in hiss wave intensity, electron flux and ultra low frequency (ULF) wave intensity exhibit remarkable correlations, while plasma density is not correlated with any of these parameters. Our study provides direct evidence for the first time that the injected anisotropic electron population, which is modulated by ULF waves, modulates the hiss intensity in the outer plasmasphere. This also implies that the plasmaspheric hiss observed by Van Allen Probe B in the outer plasmasphere (L > ∼ 5.5) is locally amplified. Meanwhile, Van Allen Probe A observed hiss emission at lower L shells (< 5), which was not associated with electron injections but primarily modulated by the plasma density. The features observed by Van Allen Probe A suggest that the observed hiss deep inside the plasmasphere may have propagated from higher L shells.

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Van Allen Probes observation of plasmaspheric hiss modulated by injected energetic electrons

10.5194/angeo-2018-2 ◽

2018 ◽

Cited By ~ 1

Author(s):

Run Shi ◽

Wen Li ◽

Qianli Ma ◽

Seth G. Claudepierre ◽

Craig A. Kletzing ◽

...

Keyword(s):

Direct Evidence ◽

Electron Flux ◽

Energetic Electron ◽

Wave Intensity ◽

Ulf Waves ◽

Electron Population ◽

Resonant Energy ◽

Ulf Wave ◽

Van Allen Probes ◽

First Time

Abstract. Plasmaspheric hiss was observed by Van Allen Probe B in association with energetic electron injections in the outer plasmasphere. The energy of injected electrons coincides with the minimum resonant energy calculated for the observed hiss wave frequency. Interestingly, the variations of hiss wave intensity, electron flux, and ULF wave intensity exhibit remarkable correlations, while plasma density is not correlated with any of these parameters. Our study provides direct evidence for the first time that the injected anisotropic electron population, which is modulated by ULF waves, modulates the hiss intensity in the outer plasmasphere. This also implies that plasmaspheric hiss observed by Van Allen Probe B in the outer plasmasphere (L > ~ 5.5) is locally amplified. Meanwhile, Van Allen Probe A observed hiss emission at lower L shells (

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BeiDa Imaging Electron Spectrometer observation of multi-period electron flux modulation caused by localized ultra-low-frequency waves

Annales Geophysicae ◽

10.5194/angeo-38-801-2020 ◽

2020 ◽

Vol 38 (4) ◽

pp. 801-813

Author(s):

Xingran Chen ◽

Qiugang Zong ◽

Hong Zou ◽

Xuzhi Zhou ◽

Li Li ◽

...

Keyword(s):

Time Delay ◽

Electron Flux ◽

Particle Interaction ◽

Energetic Electron ◽

Low Frequency ◽

Particle Energy ◽

Energy Change ◽

Electron Spectrometer ◽

Resonance Theory ◽

Energy Channels

Abstract. We present multi-period modulation of energetic electron flux observed by the BeiDa Imaging Electron Spectrometer (BD-IES) on board a Chinese navigation satellite on 13 October 2015. Electron flux oscillations were observed at a dominant period of ∼190 s in consecutive energy channels from ∼50 to ∼200 keV. Interestingly, flux modulations at a secondary period of ∼400 s were also unambiguously observed. The oscillating signals at different energy channels were observed in sequence, with a time delay of up to ∼900 s. This time delay far exceeds the oscillating periods, by which we speculate that the modulations were caused by localized ultra-low-frequency (ULF) waves. To verify the wave–particle interaction scenario, we revisit the classic drift-resonance theory. We adopt the calculation method therein to derive the electron energy change in a multi-period ULF wave field. Then, based on the modeled energy change, we construct the flux variations to be observed by a virtual spacecraft. The predicted particle signatures well agree with the BD-IES observations. We demonstrate that the particle energy change might be underestimated in the conventional theories, as the Betatron acceleration induced by the curl of the wave electric field was often omitted. In addition, we show that azimuthally localized waves would notably extend the energy width of the resonance peak, whereas the drift-resonance interaction is only efficient for particles at the resonant energy in the original theory.

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Attenuation of Plasmaspheric Hiss Associated with the Enhanced Magnetospheric Electric Field

10.5194/angeo-2021-8 ◽

2021 ◽

Author(s):

Haimeng Li ◽

Wen Li ◽

Qianli Ma ◽

Yukitoshi Nishimura ◽

Zhigang Yuan ◽

...

Keyword(s):

Solar Wind ◽

Electric Field ◽

Energetic Electron ◽

Wave Intensity ◽

Wave Amplification ◽

Model Driven ◽

Van Allen Probes ◽

Electron Distributions ◽

New Finding ◽

Substorm Activity

Abstract. We report an attenuation of hiss wave intensity in the duskside of outer plasmasphere in response to enhanced convection and substorm based on Van Allen Probes observations. Using test particle codes, we simulate the dynamics of energetic electron fluxes based on a realistic magnetospheric electric field model driven by solar wind and subauroral polarization stream. We suggest that the enhanced magnetospheric electric field causes the outward and sunward motion of energetic electrons, corresponding to the decrease of energetic electron fluxes on the duskside, leading to the subsequent attenuation of hiss wave intensity. The results indicate that the enhanced electric field can significantly change the energetic electron distributions, which provide free energy for hiss wave amplification. This new finding is critical for understanding the generation of plasmaspheric hiss and its response to solar wind and substorm activity.

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Statistical Distribution of Bifurcation of Earth's Inner Energetic Electron Belt at tens of keV

10.5194/egusphere-egu21-6003 ◽

2021 ◽

Author(s):

Man Hua ◽

Binbin Ni ◽

Wen Li ◽

Qianli Ma ◽

Xudong Gu ◽

...

Keyword(s):

Electron Energy ◽

Energetic Electron ◽

Low Frequency ◽

Inner Magnetosphere ◽

Near Earth Space ◽

Naturally Occurring ◽

Van Allen Probes ◽

Radial Structure ◽

Hemisphere Winter

The Earth&#8217;s inner energetic electron belt typically exhibits one-peak radial structure with high flux intensities at radial distances < ~2.5 Earth radii. Recent studies suggested that human-made very-low-frequency (VLF) transmitters leaked into the inner magnetosphere can efficiently scatter energetic electrons, bifurcating the inner electron belt. In this study, we use 6-year electron flux data from Van Allen Probes to comprehensively analyze the statistical distributions of the bifurcated inner electron belt and their dependence on electron energy, season, and geomagnetic activity, which is crucial to understand when and where VLF transmitters can efficiently scatter electrons in addition to other naturally occurring waves. We reveal that bifurcation can be frequently observed for tens of keV electrons under relatively quiet geomagnetic conditions, typically after significant flux enhancements that elevate fluxes at L = 2.0 &#8211; ~2.5 providing the prerequisite for the bifurcation. The bifurcation typically lasts for a few days until interrupted by substorm injections or inward radial diffusion. The L-shells of bifurcation dip decrease with increasing electron energy, and the occurrence of bifurcation is higher during northern hemisphere winter than summer, supporting the important role of VLF transmitter waves in energetic electron loss in near-Earth space.

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Observations and simulations of electron flux oscillations in response to broadband ULF waves

10.5194/egusphere-egu2020-22404 ◽

2020 ◽

Author(s):

Xinlin Li ◽

Theodoros Sarris ◽

Michael Temerin ◽

Hong Zhao ◽

Leng Ying Khoo ◽

...

Keyword(s):

Electron Flux ◽

Low Frequency ◽

Transport Processes ◽

Ulf Waves ◽

Magnetic Fluctuations ◽

Radial Transport ◽

Energy Channel ◽

Van Allen Probes ◽

Initial Results ◽

Energy Channels

It has recently been demonstrated through simulations and observations that flux oscillations of hundreds-keV electrons are produced in the magnetosphere in association with broadband Ultra Low Frequency (ULF) waves (Sarris et al., JGR, 2017). These oscillations are observed in the form of drift-periodic flux fluctuations, but are not associated with drift echoes following storm- or substorm-related energetic particle injections. They are observed in particular during quiet times, and it has been shown that they could indicate ongoing radial transport processes caused by ULF waves. It has also been shown that the width of electron energy channels is a critical parameter affecting the observed amplitude of flux oscillations, with narrower energy channel widths enabling the observation of higher-amplitude flux oscillations; this potentially explains why such features were not observed regularly before the Van Allen Probes era, as previous spacecraft generally had lower energy resolution. We extend these initial results by investigating the association between the observed flux oscillations with the amplitude of electric and magnetic fluctuations in the ULF range and with Phase Space Density gradients, both of which are expected to also affect radial transport rates.

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ULF wave activity during the 2003 Halloween superstorm: multipoint observations from CHAMP, Cluster and Geotail missions

Annales Geophysicae ◽

10.5194/angeo-30-1751-2012 ◽

2012 ◽

Vol 30 (12) ◽

pp. 1751-1768 ◽

Cited By ~ 24

Author(s):

G. Balasis ◽

I. A. Daglis ◽

E. Zesta ◽

C. Papadimitriou ◽

M. Georgiou ◽

...

Keyword(s):

Low Frequency ◽

Wave Activity ◽

Low Earth Orbit ◽

Topside Ionosphere ◽

Ulf Waves ◽

Satellite Mission ◽

Ulf Wave ◽

Activity Frequency ◽

Field Lines ◽

First Time

Abstract. We examine data from a topside ionosphere and two magnetospheric missions (CHAMP, Cluster and Geotail) for signatures of ultra low frequency (ULF) waves during the exceptional 2003 Halloween geospace magnetic storm, when Dst reached ~−380 nT. We use a suite of wavelet-based algorithms, which are a subset of a tool that is being developed for the analysis of multi-instrument multi-satellite and ground-based observations to identify ULF waves and investigate their properties. Starting from the region of topside ionosphere, we first present three clear and strong signatures of Pc3 ULF wave activity (frequency 15–100 mHz) in CHAMP tracks. We then expand these three time intervals for purposes of comparison between CHAMP, Cluster and Geotail Pc3 observations but also to be able to search for Pc4–5 wave signatures (frequency 1–10 mHz) into Cluster and Geotail measurements in order to have a more complete picture of the ULF wave occurrence during the storm. Due to the fast motion through field lines in a low Earth orbit (LEO) we are able to reliably detect Pc3 (but not Pc4–5) waves from CHAMP. This is the first time, to our knowledge, that ULF wave observations from a topside ionosphere mission are compared to ULF wave observations from magnetospheric missions. Our study provides evidence for the occurrence of a number of prominent ULF wave events in the Pc3 and Pc4–5 bands during the storm and offers a platform to study the wave evolution from high altitudes to LEO. The ULF wave analysis methods presented here can be applied to observations from the upcoming Swarm multi-satellite mission of ESA, which is anticipated to enable joint studies with the Cluster mission.

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Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013

Annales Geophysicae ◽

10.5194/angeo-33-1037-2015 ◽

2015 ◽

Vol 33 (8) ◽

pp. 1037-1050 ◽

Cited By ~ 10

Author(s):

J. Paral ◽

M. K. Hudson ◽

B. T. Kress ◽

M. J. Wiltberger ◽

J. R. Wygant ◽

...

Keyword(s):

Electric Field ◽

Low Frequency ◽

Propagation Speed ◽

Outer Zone ◽

Wave Power ◽

Radial Transport ◽

Simulation Code ◽

Azimuthal Component ◽

Ulf Wave ◽

Van Allen Probes

Abstract. Coronal mass ejection (CME)-shock compression of the dayside magnetopause has been observed to cause both prompt enhancement of radiation belt electron flux due to inward radial transport of electrons conserving their first adiabatic invariant and prompt losses which at times entirely eliminate the outer zone. Recent numerical studies suggest that enhanced ultra-low frequency (ULF) wave activity is necessary to explain electron losses deeper inside the magnetosphere than magnetopause incursion following CME-shock arrival. A combination of radial transport and magnetopause shadowing can account for losses observed at radial distances into L = 4.5, well within the computed magnetopause location. We compare ULF wave power from the Electric Field and Waves (EFW) electric field instrument on the Van Allen Probes for the 8 October 2013 storm with ULF wave power simulated using the Lyon–Fedder–Mobarry (LFM) global magnetohydrodynamic (MHD) magnetospheric simulation code coupled to the Rice Convection Model (RCM). Two other storms with strong magnetopause compression, 8–9 October 2012 and 17–18 March 2013, are also examined. We show that the global MHD model captures the azimuthal magnetosonic impulse propagation speed and amplitude observed by the Van Allen Probes which is responsible for prompt acceleration at MeV energies reported for the 8 October 2013 storm. The simulation also captures the ULF wave power in the azimuthal component of the electric field, responsible for acceleration and radial transport of electrons, at frequencies comparable to the electron drift period. This electric field impulse has been shown to explain observations in related studies (Foster et al., 2015) of electron acceleration and drift phase bunching by the Energetic Particle, Composition, and Thermal Plasma Suite (ECT) instrument on the Van Allen Probes.

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Outer radiation belt and inner magnetospheric response to sheath regions of coronal mass ejections: a statistical analysis

Annales Geophysicae ◽

10.5194/angeo-38-683-2020 ◽

2020 ◽

Vol 38 (3) ◽

pp. 683-701 ◽

Cited By ~ 3

Author(s):

Milla M. H. Kalliokoski ◽

Emilia K. J. Kilpua ◽

Adnane Osmane ◽

Drew L. Turner ◽

Allison N. Jaynes ◽

...

Keyword(s):

Coronal Mass Ejections ◽

Large Scale ◽

Electron Flux ◽

Energetic Electron ◽

Radial Distance ◽

Wave Power ◽

Electron Content ◽

Outer Radiation Belt ◽

The Earth ◽

Van Allen Probes

Abstract. The energetic electron content in the Van Allen radiation belts surrounding the Earth can vary dramatically at several timescales, and these strong electron fluxes present a hazard for spacecraft traversing the belts. The belt response to solar wind driving is, however, largely unpredictable, and the direct response to specific large-scale heliospheric structures has not been considered previously. We investigate the immediate response of electron fluxes in the outer belt that are driven by sheath regions preceding interplanetary coronal mass ejections and the associated wave activity in the inner magnetosphere. We consider the events recorded from 2012 to 2018 in the Van Allen Probes era to utilise the energy- and radial-distance-resolved electron flux observations of the twin spacecraft mission. We perform a statistical study of the events by using the superposed epoch analysis in which the sheaths are superposed separately from the ejecta and resampled to the same average duration. Our results show that the wave power of ultra-low frequency Pc5 and electromagnetic ion cyclotron waves, as measured by a Geostationary Operational Environmental Satellite (GOES), is higher during the sheath than during the ejecta. However, the level of chorus wave power, as measured by the Van Allen Probes, remains approximately the same due to similar substorm activity during the sheath and ejecta. Electron flux enhancements are common at low energies (<1 MeV) throughout the outer belt (L = 3–6), whereas depletion predominantly occurs at high energies for high radial distances (L>4). It is distinctive that the depletion extends to lower energies at larger distances. We suggest that this L-shell and energy-dependent depletion results from the magnetopause shadowing that dominates the losses at large distances, while the wave–particle interactions dominate closer to the Earth. We also show that non-geoeffective sheaths cause significant changes in the outer belt electron fluxes.

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Electron filling and proton loss in radiation belts and SAA during 2018 storm based on ZH-1 satellite observations

10.5194/egusphere-egu21-1529 ◽

2021 ◽

Author(s):

Zhenxia Zhang

Keyword(s):

Geomagnetic Storm ◽

Radiation Belt ◽

Electron Flux ◽

Outer Boundary ◽

Energetic Electron ◽

High Energy ◽

Radiation Belts ◽

High Energy Particle ◽

Van Allen Probes ◽

Proton Loss

Based on data from the ZH-1 satellites, companied with Van Allen Probes and NOAA observations, we analyze the high energy particle evolutions in radiation belts, slot region and SAA during August 2018 major geomagnetic storm (minimum Dst &#8776; &#8722;190 nT).&#160;&#160;&#160;1) Relativistic electron enhancements in extremely low L-shell regions (reaching L &#8764; 3) were observed during storm. Contrary to what occurs in the outer belt, such an intense and deep electron penetration event is rare and more interesting. Strong whistler-mode (chorus and hiss) waves, with amplitudes 81&#8211;126 pT, were also observed in the extremely low L-shell simultaneously (reaching L &#8764; 2.5) where the plasmapause was suppressed. The bounce-averaged diffusion coefficient calculations support that the chorus waves can play a significantly important role in diffusing and accelerating the 1&#8211;3 MeV electrons even in such low L-shells during storms.2) A robust evidence is clearly demonstrated that the energetic electron flux with energy 30&#8764;600 keV are increased by 2&#8764;3 times in the inner radiation belt near equator and SAA region on dayside during the major geomagnetic storm. This is the first time that the 100s keV electron flux enhancement is reported to be potentially induced by the interaction with magnetosonic waves in extremely low L-shells (L<2) observed by Van Allen Probes. Proton loss in outer boundary of inner radiation belt takes place in energy of 2~220 MeV extensively during the occurrence of this storm but the loss mechanism is energy dependence which is consistent with some previous studies. It is confirmed that the magnetic field line curvature scattering plays a significant role in the proton loss phenomenon in energy 30-100 MeV during this storm. This work provides a beneficial help to comprehensively understand the charged particles trapping and loss in SAA region and inner radiation belt dynamic physics.

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BD-IES Observation of Multi-Period Electron Flux Modulation Caused by Localized Ultra-Low Frequency Waves

10.5194/angeo-2019-139 ◽

2019 ◽

Author(s):

Xingran Chen ◽

Qiugang Zong ◽

Hong Zou ◽

Xuzhi Zhou ◽

Li Li ◽

...

Keyword(s):

Time Delay ◽

Electron Flux ◽

Particle Interaction ◽

Energetic Electron ◽

Low Frequency ◽

Particle Energy ◽

Energy Change ◽

Resonance Theory ◽

Electron Field ◽

Energy Channels

Abstract. We present multi-period modulation of energetic electron flux observed by the BeiDa Imaging Electron Spectrometer (BD-IES) onboard a Chinese navigation satellite on October 13, 2015. Electron flux oscillations were observed at a dominant period of ~ 190 s in consecutive energy channels from ~ 50 keV to ~ 200 keV. Interestingly, flux modulations at a secondary period of ~ 400 s were also unambiguously observed. The oscillating signals at different energy channels were observed in sequence, with a time delay of up to ~ 900 s. This time delay far exceeds the oscillating periods, by which we speculate that the modulations were caused by localized ultra-low frequency (ULF) waves. To verify the wave-particle interaction scenario, we revisit the classic drift-resonance theory. We adopt the calculation scheme therein to derive the electron energy change in a multi-period ULF wave field. Then, based on the modeled energy change, we construct the flux variations to be observed by a virtual spacecraft. The predicted particle signatures well agree with the BD-IES observations. We demonstrate that the particle energy change might be underestimated in the conventional theories, as the Betatron acceleration induced by the curl of the wave electron field was often omitted. In addition, we show that azimuthally localized waves would notably extend the energy width of the resonance peak, whereas the drift-resonance interaction is only efficient for particles at the resonant energy in the original theory.

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