scholarly journals Feedback on 'Semiannual variation in radiation belts particle fluxes: Van Allen Probes observations'

2018 ◽  
Author(s):  
Anonymous
Keyword(s):  
Radiation Belts ◽  
Van Allen Probes ◽  
Semiannual Variation ◽  
Particle Fluxes

Acceleration and Loss of Ultra-relativistic Electrons in the Earth Van Allen Radiation Belts

2021 ◽  
Author(s):  
Yuri Shprits ◽  
Hayley Allison ◽  
Alexander Drozdov ◽  
Dedong Wang ◽  
Nikita Aseev ◽  
...  
Keyword(s):  
Geomagnetic Storms ◽  
Local Heating ◽  
Rest Mass ◽  
Radiation Belts ◽  
Radiation Environment ◽  
Relativistic Electrons ◽  
Horizon 2020 ◽  
Probabilistic Forecasts ◽  
Van Allen Probes ◽  
Loss Mechanisms

<p>Measurements from the Van Allen Probes mission clearly demonstrated that the radiation belts cannot be considered as a bulk population above approximately electron rest mass. Ultra-relativistic electrons (~>4Mev) form a new population that shows a very different morphology (e.g. very narrow remnant belts) and slow but sporadic acceleration.</p><p>We show that acceleration to multi-MeV energies can not only result of a two-step processes consisting of local heating and radial diffusion but occurs locally due to energy diffusion by whistler mode waves. Local heating appears to be able to transport electrons in energy space from 100s of keV all the way to ultra-relativistic energies (>7MeV). Acceleration to such high energies occurs only for the conditions when cold plasma in the trough region is extremely depleted down to the values typical for the plasma sheet.</p><p>There is also a clear difference between the loss mechanisms at MeV and multi MeV energies The difference between the loss mechanisms at MeV and multi-MeV energies is due to EMIC waves that can very efficiently scatter ultra-relativistic electrons, but leave MeV electrons unaffected.</p><p>We also present how the new understanding gained from the Van Allen Probes mission can be used to produce the most accurate data assimilative forecast. Under the recently funded EU Horizon 2020 Project Prediction of Adverse effects of Geomagnetic storms and Energetic Radiation (PAGER) we will study how ensemble forecasting from the Sun can produce long-term probabilistic forecasts of the radiation environment in the inner magnetosphere.</p>

scholarly journals Radiation Belt Processes in a Declining Solar Cycle

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
A. Ukhorskiy ◽  
B. Mauk ◽  
D. Sibeck ◽  
R. Kessel
Keyword(s):  
Solar Cycle ◽  
Radiation Belt ◽  
Radiation Belts ◽  
Van Allen Probes ◽  
Earth's Radiation Belts

The Van Allen Probes began an extended mission in November to advance understanding of Earth's radiation belts.

scholarly journals EVIDENCE OF THE EARTH’S INNER RADIATION BELTS DURING THE LOW SOLAR AND GEOMAGNETIC ACTIVITY OBTAINED WITH THE STEP-F INSTRUMENT

2021 ◽  
Vol 26 (3) ◽  
pp. 224-238
Author(s):  
O. V. Dudnik ◽  
◽  
O. V. Yakovlev ◽  
Keyword(s):  
Geomagnetic Activity ◽  
Radiation Belt ◽  
Charged Particles ◽  
Radiation Belts ◽  
Outer Radiation Belt ◽  
Earth’S Magnetosphere ◽  
High Latitude Region ◽  
Wide Range ◽  
Earth's Magnetosphere ◽  
Particle Fluxes

Purpose: The subject of research is the spatio-temporal charged particles in the Earth’s magnetosphere outside the South Atlantic magnetic Anomaly during the 11-year cycle of solar activity minimum. The work aims at searching for and clarifying the sustained and unstable new spatial zones of enhanced subrelativistic electron fluxes at the altitudes of the low Earth orbit satellites. Design/methodology/approach: Finding and ascertainment of new radiation belts of the Earth were made by using the data analysis from the D1e channel of recording the electrons of energies of ΔEe=180–510 keV and protons of energies of ΔEp=3.5–3.7 MeV of the satellite telescope of electrons and protons (STEP-F) aboard the “CORONAS-Photon” Earth low-orbit satellite. For the analysis, the data array with the 2 s time resolution normalized onto the active area of the position-sensitive silicon matrix detector and onto the solid angle of view of the detector head of the instrument was used. Findings: A sustained structure of three electron radiation belts in the Earth’s magnetosphere was found at the low solar and geomagnetic activity in May 2009. The two belts are known since the beginning of the space age as the Van Allen radiation belts, another additional permanent layer is formed around the drift shell with the McIlwaine parameter of L = 1.65±0.05. On some days in May 2009, the new two inner radiation belts were observed simultaneously, one of those latter being recorded between the investigated sustained belt at L≈1.65 and the Van Allen inner belt at L≈2.52. Increased particle fluxes in this unstable belt have been formed with the drift shell L≈2.06±0.14. Conclusions: The new found inner radiation belts are recorded in a wide range of geographic longitudes λ, both at the ascending and descending nodes of the satellite orbit, from λ1≈150° to λ2≈290°. Separately in the Northern or in the Southern hemispheres, outside the outer edge of the outer radiation belt, at L≥7–8, there are cases of enhanced particle fl ux density in wide range of L-shells. These shells correspond to the high-latitude region of quasi-trapped energetic charged particles. Increased particle fluxes have been recorded up to the bow shock wave border of the Earth’s magnetosphere (L≈10-12). Key words: radiation belt, STEP-F instrument, electrons, magnetosphere, drift L-shell, particle flux density

scholarly journals OMEP-EOR: A MeV proton flux specification model for Electric Orbit Raising missions

2021 ◽  
Author(s):  
Antoine Brunet ◽  
Angélica Sicard ◽  
Constantinos Papadimitriou ◽  
Didier Lazaro ◽  
Pablo Caron
Keyword(s):  
Radiation Belt ◽  
Temporal Dynamics ◽  
Radiation Belts ◽  
Proton Flux ◽  
Radiation Environment ◽  
Solar Arrays ◽  
Proton Fluxes ◽  
Van Allen Probes ◽  
Spectrum Distribution ◽  
Gp Model

Electric Orbit Raising (EOR) for telecommunication satellites has allowed significant reduction in on-board fuel mass, at the price of extended transfer durations. These relatively long transfers, which usually span a few months, cross large spans of the radiation belts, resulting in significant exposure of the spacecraft to space radiations. Since they are not very populated, the radiation environment of intermediate regions of the radiation belts is less constrained than on popular orbits such as LEO or GEO on standard environment models. In particular, there is a need for more specific models for the MeV energy range proton fluxes, responsible for solar arrays degradations, and hence critical for EOR missions. As part of the ESA ARTES program, ONERA has developed a specification model of proton fluxes dedicated for EOR missions. This model is able to estimate the average proton fluxes between 60 keV and 20MeV on arbitrary trajectories on the typical durations of EOR transfers. A global statistical model of the radiation belts was extracted from the Van Allen Probes (RBSP) RBSPICE data. For regions with no or low sampling, simulation results from the Salammbô radiation belt model were used. A special care was taken to model the temporal dynamics of the belts on the considered mission durations. A Gaussian Process (GP) model was developed, allowing to compute analytically the distribution of the average fluxes on arbitrary mission durations. Satellites trajectories can be flown in the resulting global distribution, yielding the proton flux spectrum distribution as seen by the spacecraft. We show results of the model on a typical EOR trajectory. The obtained fluxes are compared to the standard AP8 model, the AP9 model, and validated using the THEMIS satellites data.We illustrate the expected e ect on solar cell degradation, where our model is showing an increase of up to 20% degradation prediction compared to AP8.

scholarly journals Semiannual Variation in radiation belts particle fluxes: Van Allen probes observations

2018 ◽  
Author(s):  
Facundo L. Poblet ◽  
Francisco Azpilicueta
Keyword(s):  
Energy Range ◽  
Ring Current ◽  
Electron Flux ◽  
Current System ◽  
Energy Levels ◽  
Superposed Epoch Analysis ◽  
Van Allen Probes ◽  
Semiannual Variation ◽  
Weather Parameters ◽  
Epoch Analysis

Abstract. The Semiannual Variation (SAV) is an annual pattern characterized by maxima around the equinoxes and minima near solstices observed in many space weather parameters. Several authors have studied this variation in the electron fluxes of the magnetosphere, focusing only in a few energy levels. In this investigation, Van Allen probes data are processed to extend SAV studies in electron fluxes of a wider energy range. A superposed epoch analysis was applied to data of the REPT and MagEIS instruments obtaining a clear semiannual pattern in the superposed year for L-shell values between 2.5 and 6.5. The Day Of Year (DOY) at which the highest electron flux values are detected near the September equinox coincide with the Russel & McPherron prediction. However, the DOY of the maximum expected close the March equinox occurs with a one month lag from the prediction of the accepted models. In addition, integrating over L-shell the annual DOY-L data with the semiannual pattern resulted in temporal curves that enabled to determine the energy range for which the SAV can be detected: from MeV to tens MeV energy values. Finally, an additional analysis of the fluxes of the Ring Current principal components (H+ and O+ ions) was performed, obtaining no evidence of a SAV on them. This result could indicate that the widely recognized semiannual pattern in the geomagnetic activity is related to a different current system.

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

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

<p>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≤L≤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≥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.</p>

Sign in / Sign up

Export Citation Format

Share Document