Loss mechanisms in the radiation belts: comparing dropouts and flux decays simulated and observed by PROBA-V/EPT and Van Allen Probes/MagEIS

2021 ◽  
Author(s):  
Viviane Pierrard
Keyword(s):  
Radiation Belts ◽  
Van Allen Probes ◽  
Loss Mechanisms

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 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.

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>

scholarly journals Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes

2014 ◽  
Vol 41 (2) ◽  
pp. 229-235 ◽  
Author(s):  
Zhenpeng Su ◽  
Fuliang Xiao ◽  
Huinan Zheng ◽  
Zhaoguo He ◽  
Hui Zhu ◽  
...  
Keyword(s):  
Radiation Belts ◽  
Electron Radiation ◽  
Time Dynamics ◽  
Van Allen Probes

Equatorial pitch angle distributions in Earth's radiation belts: an empirical model from Van Allen Probes data

2020 ◽  
Author(s):  
Artem Smirnov ◽  
Yuri Shprits ◽  
Hayley Allison ◽  
Nikita Aseev
Keyword(s):  
Solar Activity ◽  
Empirical Model ◽  
Pitch Angle ◽  
Electron Flux ◽  
Dynamic Pressure ◽  
Radiation Belts ◽  
Data Set ◽  
Van Allen Probes ◽  
Flux Measurements ◽  
Solar Wind Parameters

<p><span>Earth’s radiation belts comprise complex and dynamic systems, depending substantially on solar activity. The pitch angle distributions (PADs) play an important role for radiation belts modelling, as they yield information on the particle transport, source and loss processes. Yet, many missions flying in the radiation belts provide omni-directional or uni-directional electron flux measurements and do not resolve pitch angles. We propose an empirical model of the equatorial PADs and a method to retrieve PADs from omni-directional flux measurements at different energies and locations along the inclined orbits. We use the entire dataset of MagEIS and REPT instruments aboard the Van Allen Probes (RBSP) mission to analyze the equatorial pitch angle distributions in the energy range from 30 keV to 6.2 MeV. The fitting method resolves all main types of PADs, including butterfly and cap distributions, and the resulting coefficients are directly related to the PAD shapes. The developed model can be used to obtain pitch angle resolved fluxes for GPS, Arase and other missions. The proposed algorithm is applied to the GPS electron flux data set to obtain the pitch-angle resolved fluxes, which are compared to the RBSP data at a number of GPS-RBSP conjunctions. The proposed model also allows one to reconstruct the pitch-angle resolved data using LEO measurements. The dynamics of the fitting coefficients based on solar activity is discussed with respect to AE, Kp, Dst indices and solar wind parameters: velocity, density and dynamic pressure.</span></p>

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