High‐speed solar wind with southward interplanetary magnetic field causes relativistic electron flux enhancement of the outer radiation belt via enhanced condition of whistler waves

Miyoshi, Yoshizumi; Kataoka, Ryuho; Kasahara, Yoshiya; Kumamoto, A.; Nagai, T.; Thomsen, M. F.

doi:10.1002/grl.50916

Cited by 136 publications

(179 citation statements)

References 37 publications

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“…10.1002/2014JA020161 Kataoka, 2008aKataoka, , 2008bMiyoshi et al, 2013]. This may be consistent with the fact that the chorus waves tend to be continuously observed on 17-20 February during the toward sector, while they are observed only during the CIR storm on 23 February during the away sector.…”

Section: Observation and Discussionsupporting

confidence: 74%

“…Small coronal holes passed across the meridional center of the Sun during the campaign, and a relatively complex corotating interaction region (CIR) caused two small storms on 19 and 20 February; a CIR caused another geomagnetic disturbance on 22 February. These CIR storms provided favorable conditions for flux enhancement of the outer belt electrons [Miyoshi andKataoka, 2005, 2008a;Kataoka and Miyoshi, 2006], related to the chorus activity, as shown by Miyoshi et al [2007Miyoshi et al [ , 2013. There was a small storm on 15-16 February with a minimum Dst index of ∼ −60 nT.…”

Section: Observation and Discussionmentioning

confidence: 97%

“…This subauroral latitude is connected to the inner magnetosphere, where chorus waves possibly interact with high-energy electrons including ring current electrons and radiation belts via cross-energy coupling processes [e.g., Miyoshi et al, 2013]. The diversity of chorus waves suggests various types of wave-particle interaction occurring in the equatorial plane of the magnetosphere.…”

Section: Summary and Concluding Remarksmentioning

confidence: 99%

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Ground‐based ELF/VLF chorus observations at subauroral latitudes—VLF‐CHAIN Campaign

et al. 2014

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We report observations of very low frequency (VLF) and extremely low frequency (ELF) chorus waves taken during the ELF/VLF Campaign observation with High-resolution Aurora Imaging Network (VLF-CHAIN) of 17-25 February 2012 at subauroral latitudes at Athabasca (L = 4.3), Canada. ELF/VLF waves were measured continuously with a sampling rate of 100 kHz to monitor daily variations in ELF/VLF emissions and derive their detailed structures. We found quasiperiodic (QP) emissions whose repetition period changes rapidly within a period of 1 h without corresponding magnetic pulsations. QP emissions showed positive correlation between amplitude and frequency sweep rate, similarly to rising-tone elements. We found an event of nearly simultaneous enhancements of QP emissions and Pc1/electromagnetic ion cyclotron wave intensities, suggesting that the temperature anisotropy of electrons and ions developed simultaneously at the equatorial plane of the magnetosphere. We also found QP emissions whose intensity suddenly increased in association with storm sudden commencement without changing their frequency. Falling-tone ELF/VLF emissions were observed with their rate of frequency change varying from 0.7 to 0.05 kHz/s over 10 min. Bursty-patch emissions in the lower and upper frequency bands are often observed during magnetically disturbed periods. Clear systematic correlation between these various ELF/VLF emissions and cosmic noise absorption was not obtained throughout the campaign period. These observations indicate several previously unknown features of ELF/VLF emissions in subauroral latitudes and demonstrate the importance of continuous measurements for monitoring temporal variations in these emissions.

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Section: Observation and Discussionsupporting

confidence: 74%

Section: Observation and Discussionmentioning

confidence: 97%

Section: Summary and Concluding Remarksmentioning

confidence: 99%

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Ground‐based ELF/VLF chorus observations at subauroral latitudes—VLF‐CHAIN Campaign

et al. 2014

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“…They can propagate in whistler mode, and their resonant interactions with energetic particles present in the radiation belts surrounding the Earth are believed to play a very significant role in regulating the dynamics of the outer and inner belts (Helliwell 1967). For example, chorus waves are intense and naturally occurring whistler-mode emissions that originate belt particles (e.g., Inan et al 1982;Helliwell 1965;Horne et al 2005;Miyoshi et al 2013Miyoshi et al , 2003, making their monitoring necessary to help understand the dynamics of high-energy particles surrounding the Earth.…”

Section: Introductionmentioning

confidence: 99%

Polarization analysis of VLF/ELF waves observed at subauroral latitudes during the VLF-CHAIN campaign

Martinez-Calderon

Shiokawa

Ozaki

et al. 2015

Earth, Planets and Space

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Chorus wave emissions are one of the most intense naturally occurring phenomena in the very low (VLF) and extremely low frequency (ELF) ranges. They are believed to be one of the major contributors to acceleration and loss of electrons in the radiation belts. During the VLF Campaign observation with High-resolution Aurora Imaging Network (VLF-CHAIN) from 17 to 25 February 2012, several types of VLF/ELF emissions, including chorus, were observed at subauroral latitudes in Athabasca, Canada. To our knowledge, there has not been any comprehensive study of the physical properties of such emissions at these latitudes. In this study, we calculate spectral and polarization parameters of VLF/ELF waves with high temporal resolution. We found that the polarization angle of several emissions depended on both frequency and time. We suggest that the frequency-dependent events, which usually last several tens of minutes, might be the consequence of the broadening of the ray path that the waves follow from their generation region to the ground. Furthermore, time-dependent events, also lasting tens of minutes, have a polarization angle that changes from negative to positive values (or vice versa) every few minutes. We suggest that this could be due to variations of the wave duct, either near the generation region or along the wave propagation path. Using another ground station in Fort Vermillion, Canada, about 450 km northwest of Athabasca, we tracked the movements of the ionospheric exit point of three chorus emissions observed simultaneously at both stations. Although we found that movement of the ionospheric exit point does not follow a general direction, it is subject to hovering motion, suggesting that the exit point can be affected by small-scale plasma processes.

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“…The intermittent southward IMF of CIR-driven geomagnetic activities is mainly carried by the Alfvenic fluctuation in high-speed streams after the stream interface [Tsurutani et al, 1995;Gonzalez et al, 1999;Miyoshi et al, 2013]. This southward IMF will be significantly enhanced or suppressed by Russell-McPherron effect, for the influence of Russell-McPherron effect on the amplitude of southward IMF is comparable with the Alfvenic fluctuation in high-speed streams [Miyoshi and Kataoka, 2008].…”

Section: Data Set and Methodologymentioning

confidence: 96%

Relativistic electron flux dropouts in the outer radiation belt associated with corotating interaction regions

et al. 2015

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Understanding how the relativistic electron fluxes drop out in the outer radiation belt under different conditions is of great importance. To investigate which mechanisms may affect the dropouts under different solar wind conditions, 1.5–6.0 MeV electron flux dropout events associated with 223 corotating interaction regions (CIRs) from 1994 to 2003 are studied using the observations of Solar, Anomalous, Magnetospheric Particle Explorer satellite. According to the superposed epoch analysis, it is found that high solar wind dynamic pressure with the peak median value of about 7 nPa is corresponding to the dropout of the median of the radiation belt content (RBC) index to 20% of the level before stream interface arrival, whereas low dynamic pressure with the peak median value of about 3 nPa is related to the dropout of the median of RBC index to 40% of the level before stream interface arrival. Furthermore, the influences of Russell‐McPherron effect with respect to interplanetary magnetic field orientation on dropouts are considered. It is pointed out that under positive Russell‐McPherron effect (+RM effect) condition, the median of RBC index can drop to 23% of the level before stream interface arrival, while for negative Russell‐McPherron effect (−RM effect) events, the median of RBC index only drops to 37% of the level before stream interface arrival. From the evolution of phase space density profiles, the effect of +RM on dropouts can be through nonadiabatic loss.

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High‐speed solar wind with southward interplanetary magnetic field causes relativistic electron flux enhancement of the outer radiation belt via enhanced condition of whistler waves

Cited by 136 publications

References 37 publications

Ground‐based ELF/VLF chorus observations at subauroral latitudes—VLF‐CHAIN Campaign

Ground‐based ELF/VLF chorus observations at subauroral latitudes—VLF‐CHAIN Campaign

Polarization analysis of VLF/ELF waves observed at subauroral latitudes during the VLF-CHAIN campaign

Relativistic electron flux dropouts in the outer radiation belt associated with corotating interaction regions

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