Found 7 entries in the Bibliography.

Showing entries from 1 through 7


Evolution of Pitch Angle-Distributed Megaelectron Volt Electrons During Each Phase of the Geomagnetic Storm

Using Relativistic Electron Proton Telescope measurements onboard Van Allen Probes, the evolution of electron pitch angle distributions (PADs) during the different phases of magnetic storms is studied. Electron fluxes are sorted in terms of storm phase, urn:x-wiley:jgra:media:jgra55457:jgra55457-math-0001 value, energy, and magnetic local time (MLT) sectors for 55 magnetic storms from October 2012 through May 2017. To understand the potential mechanisms for the evolution of electron PADs, we fit PADs to a sinusoidal function ...

Pandya, Megha; Bhaskara, Veenadhari; Ebihara, Yusuke; Kanekal, Shrikanth; Baker, Daniel;

YEAR: 2019     DOI: 10.1029/2019JA027086

electron flux; inner magnetosphere; Pitch angle distribution; Radiation belts; Van Allen Probes

Variation of Radiation belt electron flux during CME and CIR driven geomagnetic storms: Van Allen Probes observations

Relativistic electron flux responses in the inner magnetosphere are investigated for 28 magnetic storms driven by Corotating Interaction Region (CIR) and 27 magnetic storms driven by Coronal Mass Ejection (CME), using data from the Relativistic Electron-Proton Telescope (REPT) instrument on board Van-Allen Probes from Oct-2012 to May-2017. In this present study we analyze the role of CIRs and CMEs in electron dynamics by sorting the electron fluxes in terms of averaged solar wind parameters, L-values, and energies. The major ...

Pandya, Megha; Veenadhari, B.; Ebihara, Y.; Kanekal, S.G.; Baker, D.N.;

YEAR: 2019     DOI: 10.1029/2019JA026771

electron flux; innermagnetosphere; Magnetic Storms; Radiation belt; solar wind driver; Van Allen Probes


Void structure of O + ions in the inner magnetosphere observed by the Van Allen Probes

The Van Allen Probes Helium Oxygen Proton Electron instrument observed a new type of enhancement of O+ ions in the inner magnetosphere during substorms. As the satellite moved outward in the premidnight sector, the flux of the O+ ions with energy ~10 keV appeared first in the energy-time spectrograms. Then, the enhancement of the flux spread toward high and low energies. The enhanced flux of the O+ ions with the highest energy remained, whereas the flux of the ions with lower energy vanished near apogee, forming what we call ...

Nakayama, Y.; Ebihara, Y.; Ohtani, S.; Gkioulidou, M.; Takahashi, K.; Kistler, L.; Tanaka, T.;

YEAR: 2016     DOI: 10.1002/2016JA023013

injections; nonadiabatic acceleration; substorms; Van Allen Probes

Fast modulations of pulsating proton aurora related to subpacket structures of Pc1 geomagnetic pulsations at subauroral latitudes

To understand the role of electromagnetic ion cyclotron (EMIC) waves in determining the temporal features of pulsating proton aurora (PPA) via wave-particle interactions at subauroral latitudes, high-time-resolution (1/8 s) images of proton-induced N2+ emissions were recorded using a new electron multiplying charge-coupled device camera, along with related Pc1 pulsations on the ground. The observed Pc1 pulsations consisted of successive rising-tone elements with a spacing for each element of 100 s and subpacket structures, w ...

Ozaki, M.; Shiokawa, K.; Miyoshi, Y.; Kataoka, R.; Yagitani, S.; Inoue, T.; Ebihara, Y.; Jun, C.-W; Nomura, R.; Sakaguchi, K.; Otsuka, Y.; Shoji, M.; Schofield, I.; Connors, M.; Jordanova, V.;

YEAR: 2016     DOI: 10.1002/2016GL070008

fast modulation; Pc1 geomagnetic pulsations; pulsating proton aurora; subpacket structure; Van Allen Probes; wave-particle interactions

Pulsating proton aurora caused by rising tone Pc1 waves

We found rising tone emissions with a dispersion of \~1 Hz per several tens of seconds in the dynamic spectrum of a Pc1 geomagnetic pulsation (Pc1) observed on the ground. These Pc1 rising tones were successively observed over \~30 min from 0250 UT on 14 October 2006 by an induction magnetometer at Athabasca, Canada (54.7\textdegreeN, 246.7\textdegreeE, magnetic latitude 61.7\textdegreeN). Simultaneously, a Time History of Events and Macroscale Interactions during Substorms panchromatic (THEMIS) all-sky camera detected pulsa ...

Nomura, R.; Shiokawa, K.; Omura, Y.; Ebihara, Y.; Miyoshi, Y.; Sakaguchi, K.; Otsuka, Y.; Connors, M.;

YEAR: 2016     DOI: 10.1002/2015JA021681

EMIC-triggered waves; Pc1 waves; proton aurora


Formation process of relativistic electron flux through interaction with chorus emissions in the Earth\textquoterights inner magnetosphere

We perform test particle simulations of energetic electrons interacting with whistler mode chorus emissions. We compute trajectories of a large number of electrons forming a delta function with the same energy and equatorial pitch angle. The electrons are launched at different locations along the magnetic field line and different timings with respect to a pair of chorus emissions generated at the magnetic equator. We follow the evolution of the delta function and obtain a distribution function in energy and equatorial pitch ...

Omura, Yoshiharu; Miyashita, Yu; Yoshikawa, Masato; Summers, Danny; Hikishima, Mitsuru; Ebihara, Yusuke; Kubota, Yuko;

YEAR: 2015     DOI: 10.1002/2015JA021563

Chorus; nonlinear wave-particle interaction; Particle acceleration; Radiation belts; relativistic electrons; simulation

Energetic electron precipitation associated with pulsating aurora: EISCAT and Van Allen Probe observations

Pulsating auroras show quasi-periodic intensity modulations caused by the precipitation of energetic electrons of the order of tens of keV. It is expected theoretically that not only these electrons but also sub-relativistic/relativistic electrons precipitate simultaneously into the ionosphere owing to whistler-mode wave\textendashparticle interactions. The height-resolved electron density profile was observed with the European Incoherent Scatter (EISCAT) Troms\o VHF radar on 17 November 2012. Electron density enhancements w ...

Miyoshi, Y.; Oyama, S.; Saito, S.; Kurita, S.; Fujiwara, H.; Kataoka, R.; Ebihara, Y.; Kletzing, C.; Reeves, G.; Santolik, O.; Clilverd, M.; Rodger, C.; Turunen, E.; Tsuchiya, F.;

YEAR: 2015     DOI: 10.1002/2014JA020690

EISCAT; pitch angle scattering; pulsating aurora; Van Allen Probes