Association of relativistic electron enhancements with VLF/ULF wave activity and seed electrons

The inner magnetosphere is a very important region to study, as with satellite-based communications increasing day after day, possible disruptions are especially relevant due to the possible consequences in our daily life. It is becoming very important to know how the radiation belts behave, especially during strong geomagnetic activity. The radiation belts response to geomagnetic storms and solar wind conditions is still not fully understood, as relativistic electron fluxes in the outer radiation belt can be depleted, enhanced or not affected following intense activity. Different studies show how these results vary in the face of different events. As one of the main mechanisms affecting the dynamics of the radiation belt are wave-particle interactions between relativistic electrons and ULF waves. In this work we perform a statistical study of the relationship between ULF wave power and relativistic electron fluxes in the outer radiation belt during several geomagnetic storms, by using magnetic field and particle fluxes data measured by the Van Allen Probes between 2012 and 2017. We evaluate the correlation between the changes in flux and the cumulative effect of ULF wave activity during the main and recovery phases of the storms for different position in the outer radiation belt and energy channels. Our results show that there is a good correlation between the presence of ULF waves and the changes in flux during the recovery phase of the storm and that correlations vary as a function of energy. Also, we can see in detail how the ULF power change for the electron flux at different L-shell We expect these results to be relevant for the understanding of the relative role of ULF waves in the enhancements and depletions of energetic electrons in the radiation belts for condition described.

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Intermediate-m ULF waves generated by substorm injection: a case study

Annales Geophysicae ◽

10.5194/angeo-28-1499-2010 ◽

2010 ◽

Vol 28 (8) ◽

pp. 1499-1509 ◽

Cited By ~ 16

Author(s):

T. K. Yeoman ◽

D. Yu. Klimushkin ◽

P. N. Mager

Keyword(s):

Phase Variation ◽

Wave Activity ◽

Wave Number ◽

Ulf Wave ◽

Azimuthal Wave ◽

Azimuthal Wave Number ◽

Source Particle ◽

Phase Propagation ◽

Field Lines

Abstract. A case study of SuperDARN observations of Pc5 Alfvén ULF wave activity generated in the immediate aftermath of a modest-intensity substorm expansion phase onset is presented. Observations from the Hankasalmi radar reveal that the wave had a period of 580 s and was characterized by an intermediate azimuthal wave number (m=13), with an eastwards phase propagation. It had a significant poloidal component and a rapid equatorward phase propagation (~62° per degree of latitude). The total equatorward phase variation over the wave signatures visible in the radar field-of-view exceeded the 180° associated with field line resonances. The wave activity is interpreted as being stimulated by recently-injected energetic particles. Specifically the wave is thought to arise from an eastward drifting cloud of energetic electrons in a similar fashion to recent theoretical suggestions (Mager and Klimushkin, 2008; Zolotukhina et al., 2008; Mager et al., 2009). The azimuthal wave number m is determined by the wave eigenfrequency and the drift velocity of the source particle population. To create such an intermediate-m wave, the injected particles must have rather high energies for a given L-shell, in comparison to previous observations of wave events with equatorward polarization. The wave period is somewhat longer than previous observations of equatorward-propagating events. This may well be a consequence of the wave occurring very shortly after the substorm expansion, on stretched near-midnight field lines characterised by longer eigenfrequencies than those involved in previous observations.

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Increase in relativistic electron flux in the inner magnetosphere: ULF wave mode structure

Advances in Space Research ◽

10.1016/s0273-1177(99)00518-9 ◽

2000 ◽

Vol 25 (12) ◽

pp. 2327-2337 ◽

Cited By ~ 104

Author(s):

M.K. Hudson ◽

S.R. Elkington ◽

J.G. Lyon ◽

C.C. Goodrich

Keyword(s):

Relativistic Electron ◽

Electron Flux ◽

Wave Mode ◽

Mode Structure ◽

Inner Magnetosphere ◽

Ulf Wave

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Correlations between ULF wave power, solar wind speed, and relativistic electron flux in the magnetosphere: solar cycle dependence

Journal of Atmospheric and Solar-Terrestrial Physics ◽

10.1016/j.jastp.2003.10.002 ◽

2004 ◽

Vol 66 (2) ◽

pp. 187-198 ◽

Cited By ~ 80

Author(s):

I.R. Mann ◽

T.P. O'Brien ◽

D.K. Milling

Keyword(s):

Solar Wind ◽

Solar Cycle ◽

Wind Speed ◽

Relativistic Electron ◽

Electron Flux ◽

Solar Wind Speed ◽

Wave Power ◽

Ulf Wave ◽

Cycle Dependence

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Solar wind influence on Pc4 and Pc5 ULF wave activity in the inner magnetosphere

Journal of Geophysical Research Atmospheres ◽

10.1029/2010ja015299 ◽

2010 ◽

Vol 115 (A12) ◽

pp. n/a-n/a ◽

Cited By ~ 32

Author(s):

W. Liu ◽

T. E. Sarris ◽

X. Li ◽

R. Ergun ◽

V. Angelopoulos ◽

...

Keyword(s):

Solar Wind ◽

Wave Activity ◽

Inner Magnetosphere ◽

Ulf Wave ◽

Wind Influence

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The Pulsating Magnetosphere at Jupiter

10.5194/egusphere-egu2020-3651 ◽

2020 ◽

Author(s):

Harry Manners ◽

Adam Masters

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Dynamic Pressure ◽

Wave Spectrum ◽

Low Frequency ◽

Global Scale ◽

Wave Activity ◽

Ulf Waves ◽

Ulf Wave ◽

Wide Range

The magnetosphere of Jupiter is the largest planetary magnetosphere in the solar system, and plays host to internal dynamics that remain, in many ways, mysterious. Prominent among these mysteries are the ultra-low-frequency (ULF) pulses ubiquitous in this system. Pulsations in the electromagnetic emissions, magnetic field and flux of energetic particles have been observed for decades, with little to indicate the source mechanism. While ULF waves have been observed in the magnetospheres of all the magnetized planets, the magnetospheric environment at Jupiter seems particularly conducive to the emergence of ULF waves over a wide range of periods (1-100+ minutes). This is mainly due to the high variability of the system on a global scale: internal plasma sources and a powerful intrinsic magnetic field produce a highly-compressible magnetospheric cavity, which can be reduced to a size significantly smaller than its nominal expanded state by variations in the dynamic pressure of the solar wind. Compressive fronts in the solar wind, turbulent surface interactions on the magnetopause and internal plasma processes can also all lead to ULF wave activity inside the magnetosphere.To gain the first comprehensive view of ULF waves in the Jovian system, we have performed a heritage survey of magnetic field data measured by six spacecraft that visited the magnetosphere (Galileo, Ulysses, Voyager 1 & 2 and Pioneer 10 & 11). We found several-hundred wave events consisting of wave packets parallel or transverse to the mean magnetic field, interpreted as fast-mode or Alfv&#233;nic MHD wave activity, respectively. Parallel and transverse events were often coincident in space and time, which may be evidence of global Alfv&#233;nic resonances of the magnetic field known as field-line-resonances. We found that 15-, 30- and 40-minute periods dominate the Jovian ULF wave spectrum, in agreement with the dominant &#8220;magic frequencies&#8221; often reported in existing literature.We will discuss potential driving mechanisms as informed by the results of the heritage survey, how this in turn affects our understanding of energy transfer in the magnetosphere, and potential investigations to be made using data from the JUNO spacecraft. We will also discuss the potential for multiple resonant cavities, and how the resonance modes of the Jovian magnetosphere may differ from those of the other magnetized planets.

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