Variation of Radiation Belt Electron Flux During CME‐ and CIR‐Driven Geomagnetic Storms: Van Allen Probes Observations

Recent observations from the Van Allen Probes mission have established that Pc3-5 ultra-low-frequency (ULF) waves can energize ions and electrons via drift-resonance and drift-bounce resonance. The extent to which these waves contribute to the space weather of the belts is relatively poorly understood and requires sophisticated modelling and characterization of the dominant wave modes that arise in the development and recovery phase of geomagnetic storms. Despite more than four decades of observations and theoretical analysis of ULF waves, there is no framework for accurately assessing the global distribution of ULF waves and their influence on the ring current.&#160; In this presentation, we describe a new global model of ULF waves that incorporates non-dipolar geomagnetic fields. The model is constrained using the GCPM of cold plasma density model and a specification of the ionosphere using the IRI and MSIS models. An algorithm is applied to adjust the initial plasma state to a quasi-static equilibrium that is then driven by a global convection electric field and ULF wave source. For specific observations by the Van Allen Probes and ARASE mission, the effect of these ULF waves on radiation belt ions and electrons is evaluated utilizing test-particle methodology and Liouville's theorem, which enables the phase space density to be followed and compared one-for-one with the satellite observations. &#160;

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The dynamics of the inner boundary of the outer radiation belt during geomagnetic storms

10.5194/egusphere-egu2020-19607 ◽

2020 ◽

Author(s):

Xiaofei Shi ◽

Jie Ren ◽

Qiugang Zong

Keyword(s):

Radiation Belt ◽

Electron Flux ◽

Geomagnetic Storms ◽

Minimum Energy ◽

Onset Time ◽

Recovery Phase ◽

Outer Radiation Belt ◽

H Index ◽

Late Recovery ◽

Energy Dependent

We present a statistical study of energy-dependent and L shell-dependent inner boundary of the outer radiation belt during 37 isolated geomagnetic storms using observations from Van Allen Probes from 2013 to 2017. There are mutual transformations between "V-shaped" and "S-shaped" inner boundaries during different storm phases, resulting from the competition among electron loss, radial transport and local acceleration. The radial position, onset time, Est (the minimum energy at Lst where the inner boundary starts to exhibit an S-shaped form), and the radial width of S-shaped boundary (&#916;L) are quantitatively defined according to the formation of a reversed energy spectrum (electron flux going up with increasing energies from hundreds of keV to ~1 MeV) from a kappa-like spectrum (electron flux steeply falling with increasing energies). The case and statistical results present that (1) The inner boundary has repeatable features associated with storms: the inner boundary is transformed from S-shaped to V-shaped form in several hours during the storm commencement and main phase, and retains in the V-shaped form for several days until it evolves into S-shaped during late recovery phase; (2) &#916;L shows positive correlation with SYM-H index; (3) The duration of the V-shaped form is positively correlated with the storm intensity and the duration of the recovery phase; (4) The minimum energy Est are mainly distributed in the range of 100-550 keV. All these findings have important implications for understanding the dynamics of energetic electrons in the slot region and the outer radiation belt during geomagnetic storms.

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Modelling the Rebuilding the Radiation Belt Following a Drop-out Event from Acceleration of the Seed Population

10.5194/egusphere-egu2020-18264 ◽

2020 ◽

Author(s):

Hayley Allison ◽

Yuri Shprits ◽

Sarah Glauert ◽

Richard Horne ◽

Dedong Wang

Keyword(s):

Boundary Condition ◽

Radiation Belt ◽

Electron Flux ◽

Outer Boundary ◽

Dynamic Environment ◽

Drop Out ◽

Sequence Of Events ◽

Seed Population ◽

Van Allen Probes ◽

Open Question

The Earth&#8217;s electron radiation belts are a dynamic environment and can change dramatically on short timescales. From Van Allen Probes observations, we see storm time drop-out events followed by a rapid recovery of the electron flux over a broad range of energies. Substorms can supply a seed population of new electrons to the radiation belt region, which are then energised by a number of processes, rebuilding the belts. However, how the electron flux is replenished across energy space, and the sequence of events leading to flux enhancements, remains an open question. Here we use a 3-D radiation belt model to explore how the seed population is accelerated to 1 MeV on realistic timescales, comparing the output to Van Allen Probes observations. By using a low energy boundary condition derived by POES data we encompass the whole radiation belt region, employing an open outer boundary condition. This approach isolates the contribution of seed population changes and allows electron flux variations over a broad range of L* to be studied. Using the model, we explore the contribution of both local acceleration and radial diffusion and demonstrate that the timing and duration of these two processes, particularly in relation to one another, is important to determine how the radiation belt rebuilds.

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Radiation belt electron flux variability during three CIR-driven geomagnetic storms

Journal of Atmospheric and Solar-Terrestrial Physics ◽

10.1016/j.jastp.2008.06.007 ◽

2009 ◽

Vol 71 (10-11) ◽

pp. 1145-1156 ◽

Cited By ~ 12

Author(s):

M.M. Lam ◽

R.B. Horne ◽

N.P. Meredith ◽

S.A. Glauert

Keyword(s):

Radiation Belt ◽

Electron Flux ◽

Geomagnetic Storms ◽

Flux Variability

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On the Effect of Geomagnetic Storms on Relativistic Electrons in the Outer Radiation Belt: Van Allen Probes Observations

Journal of Geophysical Research Space Physics ◽

10.1002/2017ja024735 ◽

2017 ◽

Vol 122 (11) ◽

pp. 11,100-11,108 ◽

Cited By ~ 23

Author(s):

Pablo S. Moya ◽

Víctor A. Pinto ◽

David G. Sibeck ◽

Shrikanth G. Kanekal ◽

Daniel N. Baker

Keyword(s):

Radiation Belt ◽

Geomagnetic Storms ◽

Relativistic Electrons ◽

Outer Radiation Belt ◽

Van Allen Probes

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Variability of Relativistic Electron Flux (E > 2 MeV) during Geo-Magnetically Quiet and Disturbed days: A Case Study

10.5194/angeo-2020-35 ◽

2020 ◽

Author(s):

Tulsi Thapa ◽

Binod Adhikari ◽

Prashrit Baruwal ◽

Kiran Pudasainee

Keyword(s):

Relativistic Electron ◽

Geomagnetic Storm ◽

Radiation Belt ◽

Cross Correlation ◽

Electron Flux ◽

Geomagnetic Storms ◽

Correlation Technique ◽

Outer Radiation Belt ◽

Cross Correlation Analysis ◽

Intense Storm

Abstract. We analyzed the relativistic electron fluxes (E > 2 MeV) during three different geomagnetic storms: moderate, intense, and super-intense and one geo-magnetically quiet period. We have opted Continuous wavelet analysis and cross-correlation technique to extend current understanding and of the radiation-belt dynamics. We found that the fluctuation of relativistic electron fluxes dependent basically on prolonged southward interplanetary magnetic field IMF-Bz. Cross-correlation analysis depicted that SYM-H does not show a strong connection either with relativistic electron enhancement events or persistent depletion events. Our result supports the fact that geomagnetic storms are not a primary factor that pumps up the radiation belt. In fact they seem event specific; either depletion or enhancement or slight effect on the outer radiation belt might be observed depending on the event. Solar wind pressure and velocity were found to be highly and positively correlated with relativistic electron. We found that, the count of relativistic electron flux (> 2 MeV) decreases during the main phase of geomagnetic storm with the increase in – from quiet to super intense storm – geomagnetic storm conditions (Table 1). However, Psw was found to be weakly correlated in case of intense storms following an abrupt increase of electron flux for ~ 4 hrs, which is interesting and unique.

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Increase in seismic activity near the footprints of new radiation belts forming after geomagnetic storms

10.5194/egusphere-egu21-2149 ◽

2021 ◽

Author(s):

Nursultan Toyshiev ◽

Galina Khachikyan ◽

Beibit Zhumabayev

Keyword(s):

Geomagnetic Storm ◽

Seismic Activity ◽

Radiation Belt ◽

Geomagnetic Storms ◽

Radiation Belts ◽

Tien Shan ◽

Relativistic Electrons ◽

Inner Magnetosphere ◽

Van Allen Probes ◽

Northern Tien Shan

Recently, attention was drawn [1] that after geomagnetic storms that cause formation of new radiation belts in slot region or in the inner magnetosphere, after about 2 months, there is an increase in seismic activity near the footprints of geomagnetic lines of new radiation belts. More detailed studies showed [2] that on May 30, 1991, an earthquake M=7.0 occurred in Alaska with (54.57N, 161.61E) near the footprint of geomagnetic line L = 2.69 belonging to new radiation belt, which was observed by the CRRES satellite [3] around geomagnetic lines 2<L<3 after geomagnetic storm on March 24, 1991. After geomagnetic storm on September 3, 2012, the Van Allen Probes satellites observed new radiation belt around 3.0&#8804;L&#8804;3.5 [4], and about 2 months later, on October 28, 2012, earthquake M=7.8 occurred off the coast of Canada (52.79N, 132.1W) near the footprint of geomagnetic line L=3.32 belonging to the new radiation belt. Also, Van Allen Probes observed new radiation belt around L=1.5-1.8 after geomagnetic storm on June 23, 2015 [5], and ~2 months later, in September 2015, seismic activity noticeably increased near the footprint of these geomagnetic lines. We consider variations in seismic activity in connection with the strongest geomagnetic storms in 2003 with Dst~- 400 nT (Halloween Storm) and the formation of a belt of relativistic electrons in the inner magnetosphere around L~1.5 existed until the end of 2005 as observed SAMPEX [6]. Analysis of data from the USGS global seismological catalog showed that near the footprint of geomagnetic lines L=1.4-1.6 the number of earthquakes with M&#8805;4.5 increased in 2003-2004 by ~70% compared with their number in two previous years. On the Northern Tien Shan, on December 1, 2003 a strong for the region earthquake M=6.0 occurred on the border of Kazakhstan and China (42.9N, 80.5E) near the footprint of L = 1.63, adjacent to the new radiation belt.

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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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