scholarly journals Cluster observations of simultaneous resonant interactions of ULF waves with energetic electrons and thermal ion species in the inner magnetosphere

2010 ◽  
Vol 115 (A2) ◽  
pp. n/a-n/a ◽  
Author(s):  
B. Yang ◽  
Q.-G. Zong ◽  
Y. F. Wang ◽  
S. Y. Fu ◽  
P. Song ◽  
...  
Keyword(s):  
Ulf Waves ◽  
Inner Magnetosphere ◽  
Energetic Electrons ◽  
Resonant Interactions ◽  
Ion Species

scholarly journals Modulation of chorus intensity by ULF waves deep in the inner magnetosphere

2016 ◽  
Vol 43 (18) ◽  
pp. 9444-9452 ◽  
Author(s):  
Zhiyang Xia ◽  
Lunjin Chen ◽  
Lei Dai ◽  
Seth G. Claudepierre ◽  
Anthony A. Chan ◽  
...  
Keyword(s):  
Ulf Waves ◽  
Inner Magnetosphere

scholarly journals Simultaneously Formed Wedge‐Like Structures of Different Ion Species Deep in the Inner Magnetosphere

2020 ◽  
Vol 125 (12) ◽  
Author(s):  
Jie Ren ◽  
Q. G. Zong ◽  
C. Yue ◽  
X. Z. Zhou ◽  
S. Y. Fu ◽  
...  
Keyword(s):  
Inner Magnetosphere ◽  
Ion Species

Solar wind compression induced ULF-modulation of whistler-mode waves in the deep inner magnetosphere

2021 ◽  
Author(s):  
Xiongjun Shang ◽  
Si Liu ◽  
Fuliang Xiao
Keyword(s):  
Solar Wind ◽  
Dynamic Pressure ◽  
Source Region ◽  
Rare Event ◽  
Periodic Pattern ◽  
Ulf Waves ◽  
Wave Source ◽  
Whistler Mode ◽  
Energetic Electrons ◽  
Whistler Mode Waves

<p>With observations of Van Allen Probes, we report a rare event of quasiperiodic whistler-mode waves in the dayside magnetosphere on 20 February 2014 as a response to the enhancement of solar wind dynamic pressure (P<sub>sw</sub>). The intensities of whistler-mode waves and anisotropy distributions of energetic electrons exhibit a ~5 mins quasi-periodic pattern, which is consistent with the period of synchronously observed compressional ULF waves. Based on the wave growth rates calculation, we suggest that the quasiperiodic whistler-mode waves could be generated by the energetic electrons with modulated anisotropy. The Poynting vectors of the whistler-mode waves alternate between northward and southward direction with a period twice the compressional ULF wave's near the equator, also exhibiting a clear modulated feature. This is probably because the intense ULF waves slightly altered the location of the local magnetic minimum, and thus modulated the relative direction of the wave source region respect to the spacecraft. Current results provide a direct evidence that the P<sub>sw</sub> play an important role in the generation and propagation of whistler-mode waves in the Earth's magnetosphere.</p>

Roles of magnetospheric convection on nonlinear drift resonance between electrons and ULF waves

2020 ◽  
Author(s):  
Xuzhi Zhou ◽  
Li Li ◽  
Yoshiharu Omura ◽  
Qiugang Zong ◽  
Suiyan Fu ◽  
...  
Keyword(s):  
Distribution Functions ◽  
Ulf Waves ◽  
Inner Magnetosphere ◽  
Ultralow Frequency ◽  
Magnetospheric Convection ◽  
Ulf Wave ◽  
Pendulum Equation ◽  
Drift Frequency ◽  
Strong Convection ◽  
Trapping Frequency

<p>In the Earth's inner magnetosphere, charged particles can be accelerated and transported by ultralow frequency (ULF) waves via drift resonance. We investigate the effects of magnetospheric convection on the nonlinear drift resonance process, which provides an inhomogeneity factor S to externally drive the pendulum equation that describes the particle motion in the ULF wave  field. The S factor, defined as the ratio of the driving amplitude to the square of the pendulum trapping frequency, is found to vary with magnetic local time and as a consequence, oscillates quasi-periodically at the particle drift frequency. To better understand the particle behavior governed by the driven pendulum equation, we carry out simulations to obtain the evolution of electron distribution functions in energy and L-shell phase space. We find that resonant electrons can remain trapped by the low-m ULF waves under strong convection electric  field, whereas for high-m ULF waves, the electrons trajectories can be significantly modified. More interestingly, the electron drift frequency is close to the nonlinear trapping frequency for intermediate-m ULF waves, which corresponds to chaotic motion of resonant electrons. These  findings shed new light on the nature of particle coherent and diffusive transport in the inner magnetosphere.</p>

Ultra-Low Frequency (ULF) waves originating in solar wind dynamic pressure oscillations and propagating through the magnetosheath to the inner magnetosphere

2020 ◽  
Author(s):  
Marina Georgiou ◽  
Christos Katsavrias ◽  
Ioannis Daglis ◽  
Georgios Balasis
Keyword(s):  
Solar Wind ◽  
Wavelet Transform ◽  
Dynamic Pressure ◽  
Solar Wind Dynamic Pressure ◽  
Slow Solar Wind ◽  
Ulf Waves ◽  
Pressure Oscillations ◽  
Inner Magnetosphere ◽  
Cross Wavelet ◽  
Wave Properties

<p>Several observational studies have shown that ULF oscillations of the solar wind dynamic pressure can drive periodic fluctuations in magnetic field measurements at corresponding frequencies. In this study, we use multi-spacecraft (Cluster, GOES, THEMIS and Van Allen Probes) mission measurements to investigate the propagation of pressure fluctuations-driven pulsations within the Pc5 and Pc4 frequency range (from ~0.5 to 25 mHz) into the magnetosphere. During intervals of slow solar wind — to exclude waves generated by velocity shear at the magnetopause — common periodicities in electromagnetic fields in the magnetosphere and the solar wind driver are first detected in Lomb-Scargle periodograms. Then, using the cross-wavelet transform, we examine the causal relationship and specifically, in cross-wavelet spectra and wavelet transform coherence. Lastly, spatial and temporal variations of wave properties are mapped from beyond the magnetopause to the inner magnetosphere through frequency, polarisation and power signatures of waves detected at the various probes. The observed dependence of wave properties on their localisation offers an excellent source for verification of the role that solar wind dynamic pressure oscillations as driver of ULF waves propagating through the magnetosheath into the dayside and nightside magnetosphere.</p>

Presence of cavity resonances in the inner magnetosphere

2020 ◽  
Author(s):  
Harri Laakso
Keyword(s):  
Geomagnetic Activity ◽  
Radiation Belt ◽  
Wave Mode ◽  
Cavity Resonance ◽  
Ulf Waves ◽  
Inner Magnetosphere ◽  
Half Wavelength ◽  
Cavity Resonances ◽  
String Of Pearls

<p>In the inner magnetosphere there are sharp plasma boundaries that can cause resonance cavities. The four Cluster satellites move in a string-of-pearls configuration at perigee (at L=4-5) so that they are spatially well separated but their separation is still short that at least some of them are simultaneously at different positions inside the cavity. In the presence of cavity resonance of a half wavelength, all spacecraft inside the cavity observe the same wave mode in the same phase. In this talk we analyze and present a number of cavity resonances observed by the Cluster spacecraft. Typical observed mode frequencies are between 4 - 14 mHz, depending on the size of the cavity. It appears that the occurrence of cavity resonances is well correlated with changes in geomagnetic activity and they are quite common. They tend to occur at 12-16 MLT and 21-23 MLT. These ULF waves may have a significant impact on radiation belt particles as they cover a large L shell range.</p>

scholarly journals Comparison of formulas for resonant interactions between energetic electrons and oblique whistler-mode waves

2015 ◽  
Vol 22 (5) ◽  
pp. 052902 ◽  
Author(s):  
Jinxing Li ◽  
Jacob Bortnik ◽  
Lun Xie ◽  
Zuyin Pu ◽  
Lunjin Chen ◽  
...  
Keyword(s):  
Whistler Mode ◽  
Energetic Electrons ◽  
Resonant Interactions ◽  
Whistler Mode Waves

Storm time occurrence and spatial distribution of Pc4 poloidal ULF waves in the inner magnetosphere: A Van Allen Probes statistical study

2015 ◽  
Vol 120 (6) ◽  
pp. 4748-4762 ◽  
Author(s):  
Lei Dai ◽  
Kazue Takahashi ◽  
Robert Lysak ◽  
Chi Wang ◽  
John R. Wygant ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Statistical Study ◽  
Ulf Waves ◽  
Inner Magnetosphere ◽  
Van Allen Probes
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