Wave Normal Angle Distribution of Fast Magnetosonic Waves: A Survey of Van Allen Probes EMFISIS Observations

2019 ◽  
Vol 124 (7) ◽  
pp. 5663-5674 ◽  
Author(s):  
Zhengyang Zou ◽  
Pingbing Zuo ◽  
Binbin Ni ◽  
Fengsi Wei ◽  
Zhengyu Zhao ◽  
...  
Keyword(s):  
Angle Distribution ◽  
Van Allen Probes ◽  
Wave Normal ◽  
Normal Angle

scholarly journals Propagation and Dispersion of Lightning-Generated Whistlers Measured From the Van Allen Probes

2021 ◽  
Vol 9 ◽  
Author(s):  
J.-F. Ripoll ◽  
T. Farges ◽  
D. M. Malaspina ◽  
G. S. Cunningham ◽  
G. B. Hospodarsky ◽  
...  
Keyword(s):  
Refractive Index ◽  
Standard Deviation ◽  
Wave Power ◽  
Angle Distribution ◽  
Large Wave ◽  
Small Wave ◽  
Van Allen Probes ◽  
Wave Normal ◽  
Normal Angle ◽  
Field Wave

We study the propagation and attenuation of lightning-generated whistler (LGW) waves in near-Earth space (L ≤ 3) through the statistical study of three specific quantities extracted from data recorded by NASA’s Van Allen Probes mission, from 2012 to 2019: the LGW electric and magnetic power attenuation with respect to distance from a given lightning stroke, the LGW wave normal angle in space, and the frequency-integrated LGW refractive index. We find that LGW electric field wave power decays with distance mostly quadratically in space, with a power varying between -1 and -2, while the magnetic field wave power decays mostly linearly in space, with a power varying between 0 and -1. At night only, the electric wave power decays as a quadratic law and the magnetic power as a linear law, which is consistent with electric and magnetic ground measurements. Complexity of the dependence of the various quantities is maximal at the lowest L-shells (L < 1.5) and around noon, for which LGW are the rarest in Van Allen Probes measurements. In-space near-equatorial LGW wave normal angle statistics are shown for the first time with respect to magnetic local time (MLT), L-shell (L), geographic longitude, and season. A distribution of predominantly electrostatic waves is peaked at large wave normal angle. Conversely, the distribution of electromagnetic waves with large magnetic component and small electric component is peaked at small wave normal angle. Outside these limits, we show that, as the LGW electric power increases, the LGW wave normal angle increases. But, as the LGW magnetic power increases, the LGW wave normal angle distribution becomes peaked at small wave normal angle with a secondary peak at large wave normal angle. The LGW mean wave-normal angle computed over the whole data set is 41.6° with a ∼24° standard deviation. There is a strong MLT-dependence, with the wave normal angle smaller for daytime (34.4° on average at day and 46.7° at night). There is an absence of strong seasonal and continental dependences of the wave-normal angle. The statistics of the LGW refractive index show a mean LGW refractive index is 32 with a standard deviation of ∼26. There is a strong MLT-dependence, with larger refractive index for daytime 36) than for nighttime (28). Smaller refractive index is found during Northern hemisphere summer for L-shells above 1.8, which is inconsistent with Chapman ionization theory and consistent with the so-called winter/seasonal anomaly. Local minima of the mean refractive index are observed over the three continents. Cross-correlation of these wave parameters in fixed (MLT, L) bins shows that the wave normal angle and refractive index are anti-correlated; large (small) wave normal angles correspond with small (large) refractive indexes. High power attenuation during LGW propagation from the lightning source to the spacecraft is correlated with large refractive index and anti-correlated with small wave normal angle. Correlation and anti-correlation show a smooth and continuous path from one regime (i.e. large wave normal angle, small refractive index, low attenuation) to its opposite (i.e. small wave normal angle, large refractive index, large attenuation), supporting consistency of the results.

scholarly journals Sensitivity of EMIC Wave‐Driven Scattering Loss of Ring Current Protons to Wave Normal Angle Distribution

2019 ◽  
Vol 46 (2) ◽  
pp. 590-598 ◽  
Author(s):  
Xing Cao ◽  
Binbin Ni ◽  
Danny Summers ◽  
Yuri Y. Shprits ◽  
Xudong Gu ◽  
...  
Keyword(s):  
Ring Current ◽  
Angle Distribution ◽  
Scattering Loss ◽  
Emic Wave ◽  
Wave Normal ◽  
Normal Angle

Timescales of electrons wave-particle interactions with chorus and hiss in the outer radiation belts

2020 ◽  
Author(s):  
Oleksiy Agapitov ◽  
Didier Mourenas ◽  
Anton Artemyev ◽  
Forrest Mozer ◽  
John Bonnell
Keyword(s):  
Electron Scattering ◽  
Wave Amplitude ◽  
Geomagnetic Storms ◽  
Particle Interaction ◽  
Amplitude Distribution ◽  
Electron Acceleration ◽  
Angle Distribution ◽  
Geophysical Research ◽  
Van Allen Probes ◽  
Wave Normal

<p>Electron scattering by chorus and hiss waves is an important mechanism that can lead to fast electron acceleration and loss in the inner magnetosphere. Making use of Van Allen Probes measurements, we present the factors found recently to affect the efficiency and control the predominance of the precipitation or acceleration regimes. The dependence of VLF waves frequency on latitude [1], so that the relative wave frequency goes down, leads to decreasing the electron scattering resonance latitudes. This provides an effective increase of wave amplitude due to whistler-mode wave amplitude distribution on latitude. High latitude wave extent and wave amplitude distribution on latitude determine the regime of scattering (higher latitudes) or acceleration (lower latitudes). Wave normal angle distribution and the existence of the significant oblique whistler population influence efficiency of electron scattering affects significantly the scattering rates and potentially shifts the wave-particle interaction regime during geomagnetic storms from mostly scattering to mostly acceleration [2]. Dynamics of plasma characteristics during disturbed periods, such as ω<sub>pe</sub>/Ω<sub>ce</sub> decreases (especially in the night sector) sometimes leading to very short time scales for quasi‐linear MeV electron acceleration in agreement with Van Allen Probes observations [3].  ω<sub>pe</sub>/Ω<sub>ce </sub>dynamics in the plasmasphere increases the efficiency of electron scattering by hiss.</p><p><strong> </strong></p><p><strong>References</strong></p><p>[1] Agapitov et al. (2018) Journal of Geophysical Research, https://doi.org/10.1002/2017JA024843</p><p>[2] Artemyev et al., (2016). Space Science Reviews, https://doi.org/10.1007/s11214-016-0252-5</p><p>[3] Agapitov et al., (2019) Geophysical Research Letters, https://doi.org/10.1029/2019GL083446</p>

scholarly journals Diffuse auroral scattering by whistler mode chorus waves: Dependence on wave normal angle distribution

2011 ◽  
Vol 116 (A10) ◽  
pp. n/a-n/a ◽  
Author(s):  
Binbin Ni ◽  
Richard M. Thorne ◽  
Nigel P. Meredith ◽  
Yuri Y. Shprits ◽  
Richard B. Horne
Keyword(s):  
Angle Distribution ◽  
Whistler Mode ◽  
Chorus Waves ◽  
Wave Normal ◽  
Normal Angle

Oblique whistler-mode propagation in a hot anisotropic plasma

1982 ◽  
Vol 27 (2) ◽  
pp. 199-204 ◽  
Author(s):  
S. S. Sazhin ◽  
E. M. Sazhina
Keyword(s):  
Magnetic Field ◽  
Dispersion Relation ◽  
Plasma Temperature ◽  
Anisotropic Plasma ◽  
Mode Propagation ◽  
Whistler Mode ◽  
Energy Focusing ◽  
Wave Normal ◽  
The Magnetic Field ◽  
Normal Angle

An approximate dispersion relation is obtained for quasi-longitudinal whistler mode propagation in the hot anisotropic plasma. The influence of plasma temperature and anisotropy on whistler energy focusing along the magnetic field and whistler trapping in the magnetospheric ducts are considered for the case when the whistler wave normal angle is not equal to zero.

scholarly journals Electron Microbursts Induced by Nonducted Chorus Waves

2021 ◽  
Vol 8 ◽  
Author(s):  
Lunjin Chen ◽  
Xiao-Jia Zhang ◽  
Anton Artemyev ◽  
Liheng Zheng ◽  
Zhiyang Xia ◽  
...  
Keyword(s):  
Field Line ◽  
Particle Simulation ◽  
Electron Precipitation ◽  
Outer Radiation Belt ◽  
Energetic Electrons ◽  
Chorus Waves ◽  
Wave Normal ◽  
Intense Electron ◽  
The Magnetic Field ◽  
Normal Angle

Microbursts, short-lived but intense electron precipitation observed by low-Earth-orbiting satellites, may contribute significantly to the losses of energetic electrons in the outer radiation belt. Their origin is likely due to whistler mode chorus waves, as evidenced by a strong overlap in spatial correlation of the two. Despite previous efforts on modeling bursty electron precipitation induced by chorus waves, most, if not all, rely on the assumption that chorus waves are ducted along the field line with zero wave normal angle. Such ducting is limited to cases when fine-scale plasma density irregularities are present. In contrast, chorus waves propagate in a nonducted way in plasmas with smoothly varying density, allowing wave normals to gradually refract away from the magnetic field line. In this study, the interaction of ducted and nonducted chorus waves with energetic electrons is investigated using test particle simulation. Substantial differences in electron transport are found between the two different scenarios, and resultant electron precipitation patterns are compared. Such a comparison is valuable for interpreting low Earth-orbiting satellite observations of electron flux variation in response to the interaction with magnetospheric chorus waves.

On the instability of synchrotron radiation

1968 ◽  
Vol 46 (9) ◽  
pp. 1073-1081 ◽  
Author(s):  
P. C. W. Fung
Keyword(s):  
Growth Rate ◽  
Synchrotron Radiation ◽  
Magnetoactive Plasma ◽  
Kinetic Approach ◽  
Relativistic Electrons ◽  
Wave Normal ◽  
Quantum Treatment ◽  
Normal Angle

In a system of isotropic relativistic electrons which is embedded in a cold ambient magnetoactive plasma, the growth rate of synchrotron radiation at wave normal angle θ = 90° is derived by means of the classical kinetic approach. It is shown that the result is identical with that obtained from the quantum treatment. Two errors occurring in the literature of synchrotron radiation are pointed out. The growth rate is computed for the case of monoenergetic electrons as an example.

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