Drifting holes in the energetic electron flux at geosynchronous orbit following substorm onset

1992 ◽  
Vol 97 (A5) ◽  
pp. 6541 ◽  
Author(s):  
V. A. Sergeev ◽  
T. Bösinger ◽  
R. D. Belian ◽  
G. D. Reeves ◽  
T. E. Cayton
Keyword(s):  
Electron Flux ◽  
Energetic Electron ◽  
Substorm Onset ◽  
Geosynchronous Orbit

scholarly journals Observations at geosynchronous orbit of a persistent Pc5 geomagnetic pulsation and energetic electron flux modulations

2007 ◽  
Vol 25 (7) ◽  
pp. 1653-1667 ◽  
Author(s):  
T. E. Sarris ◽  
T. M. Loto'aniu ◽  
X. Li ◽  
H. J. Singer
Keyword(s):  
Spectral Analysis ◽  
Electron Flux ◽  
Narrow Band ◽  
Resonance Effect ◽  
Energetic Electron ◽  
Conclusive Evidence ◽  
Geosynchronous Orbit ◽  
Net Energy ◽  
Pulsation Frequency ◽  
External Fluctuations

Abstract. A long lasting narrow-band (4–7 mHz) Pc5 fluctuation event at geosynchronous orbit is presented through measurements from GOES-8 and GOES-10 and the response of energetic electrons with drift frequencies close to the narrow-band pulsation frequency is monitored through a spectral analysis of flux data from the LANL-SOPA energetic electron instrument. This analysis shows electron flux modulations at the magnetospheric pulsation's frequency as well as at various other frequencies in the Pc5 range, related to the particles' drift-frequencies and their harmonics. A drift resonance effect can be seen, with electron flux modulation becoming more evident in the energy channels of electrons with drift frequencies closer to the wave frequency; however no net increase or decrease in energetic electron flux is observed, indicating that the net energy transfer and transport of electrons is not significant. This Pc5 event has a long duration, being observed for more than a couple of days at geosynchronous orbit over several traversals of the two GOES satellites, and is localized in azimuthal extent. Spectral analysis shows that most of the power is in the transverse components. The frequency of the narrow-band event, as observed at geosynchronous orbit shifts during the time of the event from 7±0.5 mHz to about 4±0.5 mHz. On the ground, CARISMA magnetometers record no distinct narrow-band fluctuation in the magnetic field, and neither does Geotail, which is traversing the outer magnetosphere a few RE further out from geosynchronous orbit, at the same UT and LT that GOES-8 and -10 observe the pulsations, suggesting that that there is no connection to external fluctuations originating in the solar wind. An internal generation mechanism is suggested, such as could be provided by energetic ring current particles, even though conclusive evidence could not be provided for this particular event. Through a statistical study, it is found that this event belongs to a class of similar events, occurring predominantly in the post-noon region in the inner magnetosphere.

scholarly journals Strong localized variations of the low-altitude energetic electron fluxes in the evening sector near the plasmapause

1998 ◽  
Vol 16 (1) ◽  
pp. 25-33 ◽  
Author(s):  
E. E. Titova ◽  
T. A. Yahnina ◽  
A. G. Yahnin ◽  
B. B. Gvozdevsky ◽  
A. A. Lyubchich ◽  
...  
Keyword(s):  
Sharp Increase ◽  
Electron Flux ◽  
Particle Interaction ◽  
Energetic Electron ◽  
Recovery Phase ◽  
Electron Precipitation ◽  
Statistical Characteristics ◽  
Evening Sector ◽  
Proton Precipitation ◽  
Low Altitude

Abstract. Specific type of energetic electron precipitation accompanied by a sharp increase in trapped energetic electron flux are found in the data obtained from low-altitude NOAA satellites. These strongly localized variations of the trapped and precipitated energetic electron flux have been observed in the evening sector near the plasmapause during recovery phase of magnetic storms. Statistical characteristics of these structures as well as the results of comparison with proton precipitation are described. We demonstrate the spatial coincidence of localized electron precipitation with cold plasma gradient and whistler wave intensification measured on board the DE-1 and Aureol-3 satellites. A simultaneous localized sharp increase in both trapped and precipitating electron flux could be a result of significant pitch-angle isotropization of drifting electrons due to their interaction via cyclotron instability with the region of sharp increase in background plasma density.Key words. Ionosphere (particle precipitation; wave-particle interaction) Magnetospheric Physics (plasmasphere)

scholarly journals Comparison of energetic electron flux and phase space density in the magnetosheath and in the magnetosphere

2012 ◽  
Vol 117 (A5) ◽  
pp. n/a-n/a ◽  
Author(s):  
Bingxian Luo ◽  
Xinlin Li ◽  
Weichao Tu ◽  
Jiancun Gong ◽  
Siqing Liu
Keyword(s):  
Phase Space ◽  
Electron Flux ◽  
Energetic Electron ◽  
Phase Space Density ◽  
Space Density

scholarly journals Multi-satellite simultaneous observations of magnetopause and atmospheric losses of radiation belt electrons during an intense solar wind dynamic pressure pulse

2016 ◽  
Vol 34 (5) ◽  
pp. 493-509 ◽  
Author(s):  
Zheng Xiang ◽  
Binbin Ni ◽  
Chen Zhou ◽  
Zhengyang Zou ◽  
Xudong Gu ◽  
...  
Keyword(s):  
Solar Wind ◽  
Radiation Belt ◽  
Pressure Pulse ◽  
Electron Flux ◽  
Dynamic Pressure ◽  
Energetic Electron ◽  
Solar Wind Dynamic Pressure ◽  
Angle Scattering ◽  
Radiation Belt Electrons ◽  
Atmospheric Loss

<p><strong>Abstract.</strong> Radiation belt electron flux dropouts are a kind of drastic variation in the Earth's magnetosphere, understanding of which is of both scientific and societal importance. Using electron flux data from a group of 14 satellites, we report multi-satellite simultaneous observations of magnetopause and atmospheric losses of radiation belt electrons during an event of intense solar wind dynamic pressure pulse. When the pulse occurred, magnetopause and atmospheric loss could take effect concurrently contributing to the electron flux dropout. Losses through the magnetopause were observed to be efficient and significant at <i>L</i> ≳ 5, owing to the magnetopause intrusion into <i>L</i> ∼ 6 and outward radial diffusion associated with sharp negative gradient in electron phase space density. Losses to the atmosphere were directly identified from the precipitating electron flux observations, for which pitch angle scattering by plasma waves could be mainly responsible. While the convection and substorm injections strongly enhanced the energetic electron fluxes up to hundreds of keV, they could delay other than avoid the occurrence of electron flux dropout at these energies. It is demonstrated that the pulse-time radiation belt electron flux dropout depends strongly on the specific interplanetary and magnetospheric conditions and that losses through the magnetopause and to the atmosphere and enhancements of substorm injection play an essential role in combination, which should be incorporated as a whole into future simulations for comprehending the nature of radiation belt electron flux dropouts.</p>

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

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.

scholarly journals Comparison between CNA and energetic electron precipitation: simultaneous observation by Poker Flat Imaging Riometer and NOAA satellite

2005 ◽  
Vol 23 (5) ◽  
pp. 1555-1563 ◽  
Author(s):  
Y.-M. Tanaka ◽  
M. Ishii ◽  
Y. Murayama ◽  
M. Kubota ◽  
H. Mori ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Electron Flux ◽  
Energetic Electron ◽  
Energetic Particles ◽  
Electron Precipitation ◽  
Angle Distribution ◽  
Pitch Angle Distribution ◽  
Loss Cone ◽  
Isotropic Pitch ◽  
Trapped Electron

Abstract. The cosmic noise absorption (CNA) is compared with the precipitating electron flux for 19 events observed in the morning sector, using the high-resolution data obtained during the conjugate observations with the imaging riometer at Poker Flat Research Range (PFRR; 65.11° N, 147.42° W), Alaska, and the low-altitude satellite, NOAA 12. We estimate the CNA, using the precipitating electron flux measured by NOAA 12, based on a theoretical model assuming an isotropic pitch angle distribution, and quantitatively compare them with the observed CNA. Focusing on the eight events with a range of variation larger than 0.4dB, three events show high correlation between the observed and estimated CNA (correlation coefficient (r0)>0.7) and five events show low correlation (r0<0.5). The estimated CNA is often smaller than the observed CNA (72% of all data for 19 events), which appears to be the main reason for the low-correlation events. We examine the assumption of isotropic pitch angle distribution by using the trapped electron flux measured at 80° zenith angle. It is shown that the CNA estimated from the trapped electron flux, assuming an isotropic pitch angle distribution, is highly correlated with the observed CNA and is often overestimated (87% of all data). The underestimate (overestimate) of CNA derived from the precipitating (trapped) electron flux can be interpreted in terms of the anisotropic pitch angle distribution similar to the loss cone distribution. These results indicate that the CNA observed with the riometer may be quantitatively explained with a model based on energetic electron precipitation, provided that the pitch angle distribution and the loss cone angle of the electrons are taken into account. Keywords. Energetic particles, precipitating – Energetic particles, trapped – Ionosphere-magnetosphere interactions

scholarly journals Specification of > 2 MeV electron flux as a function of local time and geomagnetic activity at geosynchronous orbit

Space Weather ◽  
2014 ◽  
Vol 12 (7) ◽  
pp. 470-486 ◽  
Author(s):  
Yi-Jiun Su ◽  
Jack M. Quinn ◽  
W. Robert Johnston ◽  
James P. McCollough ◽  
Michael J. Starks
Keyword(s):  
Local Time ◽  
Geomagnetic Activity ◽  
Electron Flux ◽  
Geosynchronous Orbit

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.

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