Energetic electron injections deep into the inner magnetosphere associated with substorm activity

2015 ◽  
Vol 42 (7) ◽  
pp. 2079-2087 ◽  
Author(s):  
D. L. Turner ◽  
S. G. Claudepierre ◽  
J. F. Fennell ◽  
T. P. O'Brien ◽  
J. B. Blake ◽  
...  
Keyword(s):  
Energetic Electron ◽  
Inner Magnetosphere ◽  
Substorm Activity

scholarly journals Observation of reconnection pulses by Cluster and Double Star

2005 ◽  
Vol 23 (8) ◽  
pp. 2921-2927 ◽  
Author(s):  
X. H. Deng ◽  
R. X. Tang ◽  
R. Nakamura ◽  
W. Baumjohann ◽  
T. L. Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Energetic Electron ◽  
Curvature Vector ◽  
Double Star ◽  
Neutral Sheet ◽  
Inner Magnetosphere ◽  
Point Analysis ◽  
Earthward Flow ◽  
Tailward Flow ◽  
The Magnetic Field

Abstract. During a reconnection event on 7 August 2004, Cluster and Double Star (TC-1) were near the neutral sheet and simultaneously detected the signatures of the reconnection pulses. AT 22:59 UT tailward flow followed by earthward flow was detected by Cluster at about 15 RE, while earthward plasma flow followed by tailward flow was observed by TC-1 at about 10 RE. During the flow reversal from tailward to earthward, the magnetic field Bz changed sign from mainly negative values to positive, and the X component of the magnetic curvature vector switched sign from the tailward direction to the earthward direction, which indicates that the reconnection site (X-line) moved tailward past the Cluster constellation. By using multi-point analysis and observation of energetic electron and ion flux, we study the movement and structure of the current sheet and discuss the braking effect of the earthward flow bursts in the inner magnetosphere.

scholarly journals Magnetic dipolarizations inside geosynchronous orbit with tailward ion flows

2019 ◽  
Vol 37 (3) ◽  
pp. 289-297 ◽  
Author(s):  
Xiaoying Sun ◽  
Weining William Liu ◽  
Suping Duan
Keyword(s):  
Plasma Sheet ◽  
Sharp Increase ◽  
Energetic Electron ◽  
Elevation Angle ◽  
Time History ◽  
Geosynchronous Orbit ◽  
Inner Magnetosphere ◽  
Transfer Path ◽  
New Energy ◽  
History Of

Abstract. Electromagnetic field and plasma data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) near-Earth probes are used to investigate magnetic dipolarizations inside geosynchronous orbit on 27 August 2014 during an intense substorm with AEmax∼1000 nT. THEMIS-D (TH-D) was located inside geosynchronous orbit around midnight in the interval from 09:25 to 09:55 UT. During this period, two distinct magnetic dipolarizations with tailward ion flows are observed by TH-D. The first one is indicated by the magnetic elevation angle increase from 15 to 25∘ around 09:30:40 UT. The tailward perpendicular velocity is V⊥x∼-50 km s−1. The second one is presented by the elevation angle increase from 25 to 45∘ around 09:36 UT, and the tailward perpendicular velocity is V⊥x∼-70 km s−1. These two significant dipolarizations are accompanied with the sharp increase in the energy flux of energetic electron inside geosynchronous orbit. After a 5 min expansion of the near-Earth plasma sheet (NEPS), THEMIS-E (TH-E) located outside geosynchronous orbit also detected this tailward expanding plasma sheet with ion flows of −150 km s−1. The dipolarization propagates tailward with a speed of −47 km s−1 along a 2.2 RE distance in the X direction between TH-D and TH-E within 5 min. These dipolarizations with tailward ion flows observed inside geosynchronous orbit indicate a new energy transfer path in the inner magnetosphere during substorms.

scholarly journals Attenuation of Plasmaspheric Hiss Associated with the Enhanced Magnetospheric Electric Field

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.

scholarly journals The driving mechanisms of particle precipitation during the moderate geomagnetic storm of 7 January 2005

2007 ◽  
Vol 25 (9) ◽  
pp. 2053-2068 ◽  
Author(s):  
N. Longden ◽  
F. Honary ◽  
A. J. Kavanagh ◽  
J. Manninen
Keyword(s):  
Solar Wind ◽  
Geomagnetic Storm ◽  
Geomagnetic Activity ◽  
Dynamic Pressure ◽  
Energetic Electron ◽  
Recovery Phase ◽  
Global Scale ◽  
Electron Precipitation ◽  
Particle Precipitation ◽  
Substorm Activity

Abstract. The arrival of an interplanetary coronal mass ejection (ICME) triggered a sudden storm commencement (SSC) at ~09:22 UT on the 7 January 2005. The ICME followed a quiet period in the solar wind and interplanetary magnetic field (IMF). We present global scale observations of energetic electron precipitation during the moderate geomagnetic storm driven by the ICME. Energetic electron precipitation is inferred from increases in cosmic noise absorption (CNA) recorded by stations in the Global Riometer Array (GLORIA). No evidence of CNA was observed during the first four hours of passage of the ICME or following the sudden commencement (SC) of the storm. This is consistent with the findings of Osepian and Kirkwood (2004) that SCs will only trigger precipitation during periods of geomagnetic activity or when the magnetic perturbation in the magnetosphere is substantial. CNA was only observed following enhanced coupling between the IMF and the magnetosphere, resulting from southward oriented IMF. Precipitation was observed due to substorm activity, as a result of the initial injection and particles drifting from the injection region. During the recovery phase of the storm, when substorm activity diminished, precipitation due to density driven increases in the solar wind dynamic pressure (Pdyn) were identified. A number of increases in Pdyn were shown to drive sudden impulses (SIs) in the geomagnetic field. While many of these SIs appear coincident with CNA, SIs without CNA were also observed. During this period, the threshold of geomagnetic activity required for SC driven precipitation was exceeded. This implies that solar wind density driven SIs occurring during storm recovery can drive a different response in particle precipitation to typical SCs.

scholarly journals Energetic Electron Injections Deep Into the Inner Magnetosphere: A Result of the Subauroral Polarization Stream (SAPS) Potential Drop

2018 ◽  
Vol 45 (9) ◽  
pp. 3811-3819 ◽  
Author(s):  
Solène Lejosne ◽  
B. S. R. Kunduri ◽  
F. S. Mozer ◽  
D. L. Turner
Keyword(s):  
Energetic Electron ◽  
Potential Drop ◽  
Inner Magnetosphere

scholarly journals Attenuation of plasmaspheric hiss associated with the enhanced magnetospheric electric field

2021 ◽  
Vol 39 (3) ◽  
pp. 461-470
Author(s):  
Haimeng Li ◽  
Wen Li ◽  
Qianli Ma ◽  
Yukitoshi Nishimura ◽  
Zhigang Yuan ◽  
...  
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Field Model ◽  
Energetic Electron ◽  
Wave Intensity ◽  
Wave Amplification ◽  
Model Driven ◽  
Electron Distributions ◽  
New Finding ◽  
Substorm Activity

Abstract. We report an attenuation of hiss wave intensity in the duskside of the outer plasmasphere in response to enhanced convection and a substorm based on Van Allen Probe 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.

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

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

<p>The Earth’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 – ~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.</p>

Association of chorus waves and source/seed electrons with the enhancement of relativistic electrons in the outer Van Allen belt

2020 ◽  
Author(s):  
Afroditi Nasi ◽  
Ioannis A. Daglis ◽  
Christos Katsavrias ◽  
Wen Li
Keyword(s):  
Relativistic Electron ◽  
Radiation Belt ◽  
Geomagnetic Disturbance ◽  
Relativistic Electrons ◽  
Outer Radiation Belt ◽  
Inner Magnetosphere ◽  
Superposed Epoch Analysis ◽  
Chorus Waves ◽  
Substorm Activity ◽  
Epoch Analysis

<p>Local acceleration driven by whistler-mode chorus waves is fundamentally important for the acceleration of seed electrons in the outer radiation belt to relativistic energies. Τhis mechanism strongly depends on substorm activity and on the source electron population injected by the substorms into the inner magnetosphere. In our work we use Van Allen Probes data to investigate the features of source electrons, seed electrons and chorus waves for events of enhancement versus events of depletion of relativistic electrons in the outer Van Allen belt. To that end we calculate the electron phase space density (PSD) for five values of the first adiabatic invariant corresponding to source and seed electrons, and we perform a superposed epoch analysis of 28 geomagnetic disturbance events, out of which, 20 result in enhancement and 8 in depletion of relativistic electron PSD. Our results indicate that events resulting in significant enhancement of relativistic electron PSD in the outer radiation belt are characterized by statistically stronger and more prolonged storm and substorm activity, leading to more efficient injections of source but mostly seed electrons to the inner magnetosphere, and also to more pronounced and long-lasting chorus and Pc5 wave activity. The effect of these parameters in the acceleration of electrons seems to be determined by the abundance of seed electrons at the region of L*=4-5.</p>

scholarly journals MDS-1 Observations of Highly Energetic Electron Environment in the Inner Magnetosphere

2009 ◽  
Vol 7 (ists26) ◽  
pp. Tr_2_11-Tr_2_14 ◽  
Author(s):  
Takahiro OBARA ◽  
Haruhisa MATSUMOTO ◽  
Kiyokazu KOGA ◽  
Hideki KOSHIISHI ◽  
Tateo GOKA
Keyword(s):  
Energetic Electron ◽  
Inner Magnetosphere
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