scholarly journals Van Allen Probes observations linking radiation belt electrons to chorus waves during 2014 multiple storms

2015 ◽  
Vol 120 (2) ◽  
pp. 938-948 ◽  
Author(s):  
Si Liu ◽  
Fuliang Xiao ◽  
Chang Yang ◽  
Yihua He ◽  
Qinghua Zhou ◽  
...  
Keyword(s):  
Radiation Belt ◽  
Chorus Waves ◽  
Van Allen Probes ◽  
Radiation Belt Electrons

Simulations of the Relativistic Radiation Belt Electrons Using the VERB-3D Code

2021 ◽  
Author(s):  
Dedong Wang ◽  
Yuri Shprits ◽  
Alexander Drozdov ◽  
Nikita Aseev ◽  
Irina Zhelavskaya ◽  
...  
Keyword(s):  
Space Weather ◽  
Radiation Belt ◽  
Model Performance ◽  
Dynamic Evolution ◽  
Relativistic Electrons ◽  
Outer Radiation Belt ◽  
Chorus Waves ◽  
Van Allen Probes ◽  
Radiation Belt Electrons ◽  
Simulation Results

<p>Using the three-dimensional Versatile Electron Radiation Belt (VERB-3D) code, we perform simulations to investigate the dynamic evolution of relativistic electrons in the Earth’s outer radiation belt. In our simulations, we use data from the Geostationary Operational Environmental Satellites (GOES) to set up the outer boundary condition, which is the only data input for simulations. The magnetopause shadowing effect is included by using last closed drift shell (LCDS), and it is shown to significantly contribute to the dropouts of relativistic electrons at high $L^*$. We validate our simulation results against measurements from Van Allen Probes. In long-term simulations, we test how the latitudinal dependence of chorus waves can affect the dynamics of the radiation belt electrons. Results show that the variability of chorus waves at high latitudes is critical for modeling of megaelectron volt (MeV) electrons. We show that, depending on the latitudinal distribution of chorus waves under different geomagnetic conditions, they cannot only produce a net acceleration but also a net loss of MeV electrons. Decrease in high‐latitude chorus waves can tip the balance between acceleration and loss toward acceleration, or alternatively, the increase in high‐latitude waves can result in a net loss of MeV electrons. Variations in high‐latitude chorus may account for some of the variability of MeV electrons. </p><p>Our simulation results for the NSF GEM Challenge Events show that the position of the plasmapause plays a significant role in the dynamic evolution of relativistic electrons. We also perform simulations for the COSPAR International Space Weather Action Team (ISWAT) Challenge for the year 2017. The COSPAR ISWAT is a global hub for collaborations addressing challenges across the field of space weather. One of the objectives of the G3-04 team “Internal Charging Effects and the Relevant Space Environment” is model performance assessment and improvement. One of the expected outputs is a more systematic assessment of model performance under different conditions. The G3-04 team proposed performing benchmarking challenge runs. We ‘fly’ a virtual satellite through our simulation results and compare the simulated differential electron fluxes at 0.9 MeV and 57.27 degrees local pitch-angle with the fluxes measured by the Van Allen Probes. In general, our simulation results show good agreement with observations. We calculated several different matrices to validate our simulation results against satellite observations.</p>

scholarly journals Intense low‐frequency chorus waves observed by Van Allen Probes: Fine structures and potential effect on radiation belt electrons

2016 ◽  
Vol 43 (3) ◽  
pp. 967-977 ◽  
Author(s):  
Zhonglei Gao ◽  
Zhenpeng Su ◽  
Hui Zhu ◽  
Fuliang Xiao ◽  
Huinan Zheng ◽  
...  
Keyword(s):  
Radiation Belt ◽  
Low Frequency ◽  
Potential Effect ◽  
Chorus Waves ◽  
Van Allen Probes ◽  
Radiation Belt Electrons ◽  
Fine Structures

Controlling Effect of Wave Models and Plasma Boundaries on the Dynamic Evolution of Relativistic Radiation Belt Electrons

2020 ◽  
Author(s):  
Dedong Wang ◽  
Yuri Shprits ◽  
Irina Zhelavskaya ◽  
Alexander Drozdov ◽  
Nikita Aseev ◽  
...  
Keyword(s):  
Radiation Belt ◽  
Dynamic Evolution ◽  
Relativistic Electrons ◽  
Electron Radiation ◽  
Energy Diffusion ◽  
Chorus Waves ◽  
Latitudinal Dependence ◽  
Shadowing Effect ◽  
Radiation Belt Electrons ◽  
Wave Models

<p>Modeling and observations have shown that energy diffusion by chorus waves is an important source of acceleration of electrons to relativistic energies. By performing long‐term simulations using the three‐dimensional Versatile Electron Radiation Belt (VERB-3D) code, we test how the latitudinal dependence of chorus waves can affect the dynamics of the radiation belt electrons. Results show that the variability of chorus waves at high latitudes is critical for modeling of megaelectron volt (MeV) electrons. We show that, depending on the latitudinal distribution of chorus waves under different geomagnetic conditions, they cannot only produce a net acceleration but also a net loss of MeV electrons. Decrease in high‐latitude chorus waves can tip the balance between acceleration and loss toward acceleration, or alternatively, the increase in high‐latitude waves can result in a net loss of MeV electrons. Variations in high‐latitude chorus may account for some of the variability of MeV electrons.</p><p>Our simulation results also show that the position of the plasmapause plays a significant role in the dynamic evolution of relativistic electrons. The magnetopause shadowing effect is included by using last closed drift shell (LCDS), and it is shown to significantly contribute to the dropouts of relativistic electrons at high L*.</p>

Global Morphology of Lower-band Chorus Wave Intensity Reconstructed Using multi-year POES Electron Measurements

2020 ◽  
Author(s):  
Yang Zhang ◽  
Binbin Ni ◽  
Xudong Gu ◽  
Yuri Shprits ◽  
Song Fu ◽  
...  
Keyword(s):  
Radiation Belt ◽  
Wave Intensity ◽  
Global Distribution ◽  
Loss Cone ◽  
Wave Measurements ◽  
Lower Band ◽  
Chorus Waves ◽  
Radiation Belt Electrons ◽  
Chorus Wave

<p><span>Magnetospheric chorus is known to play a significant role in the acceleration and loss of radiation belt electrons. Interactions of chorus waves with radiation belt particles are commonly evaluated using quasi-linear diffusion codes that rely on statistical models, which might not accurately provide the instantaneous global wave distribution from limited in-situ wave measurements. Thus, a novel technique capable of inferring wave amplitudes from POES particle measurements, with an extensive coverage of L-shell and magnetic local time, has been established to obtain event-specific, global dynamic evolutions of chorus waves. This study, using 5 years of POES electron data, further improves the technique, and enables us to subsequently infer the chorus wave amplitudes for all useful data points (removing the electrons which were in the drift loss cone) and to construct the global distribution of lower-band chorus wave intensity. The results obtained from the improved technique reproduce Van Allen Probes in-situ observations of chorus waves reasonably well and reconstruct the major features of the global distribution of chorus waves. We demonstrate that such a data-based, dynamic model can provide near-real-time estimates of chorus wave intensity on a global scale for any time period when POES data are available, which cannot be obtained from in-situ wave measurements by equatorial satellites alone, but is crucial for quantifying the  dynamics of the radiation belt electrons.</span></p>

A Neural Network Model of Three-dimensional Magnetospheric Chorus Waves

2020 ◽  
Author(s):  
Yingjie Guo ◽  
Binbin Ni ◽  
Dedong Wang ◽  
Yuri Shprits ◽  
Song Fu ◽  
...  
Keyword(s):  
Neural Network ◽  
Radiation Belt ◽  
Time Windows ◽  
Three Dimensional ◽  
Root Mean Square Amplitude ◽  
Chorus Waves ◽  
Radiation Belt Electrons ◽  
Solar Wind Parameters ◽  
Electron Gyrofrequency ◽  
Feature Selection Techniques

<p>The evolution of chorus waves is important in the inner magnetosphere since it is closely related to the loss and acceleration of radiation belt electrons. In this study, we develop neural-network-based models for upper-band chorus (UBC; 0.5 f<sub>ce </sub>< f <  f<sub>ce </sub>) waves and lower-band chorus (LBC; 0.05 f<sub>ce </sub>< f < 0.5 f<sub>ce</sub>) waves, where f<sub>ce</sub> is the equatorial electron gyrofrequency. We establish a root-mean-square amplitude database for both UBC and LBC using Van Allen Probe levels 2 and 3 data products from the EMFISIS payload between October 1, 2012 and January 14, 2018. Based on the database, we construct an artificial neural network with corresponding L, magnetic local time, magnetic latitude, solar wind parameters and geomagnetic indices on different time windows as model inputs. Additionally, we adopt several different feature selection techniques to determine the most important features of magnetospheric chorus waves, reduce training or running time and improve the model accuracy. Our study suggests that the model results using the machine learning technique have the great potential to highly improve current understanding of the radiation belt dynamics.</p>

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