Characteristics of monoenergetic and broadband auroral electron precipitation as observed by the Science and Technology Satellite‐I

Park, J.; Kang, Min; Lim, Yeo-Myeong; Jc, Lee; Lee, Joseph; Kim, H. J.; Hwang, Junga

doi:10.1002/2013ja019497

Cited by 3 publications

(3 citation statements)

References 56 publications

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“…Based on the Cluster observations, Sadeghi et al (2011) reported the characteristics found in the energytime (E-t) spectrograms and field-aligned current distributions obtained in neighboring potential structures. Park et al (2014) also showed similar properties of monoenergetic and broadband auroral electron components observed by the Science and Technology Satellite-I in addition to their electron energy distributions and statistical results on the basic parameters (characteristic energy, energy flux, pitch angle, temperature, and density) and spatial (invariant latitude-magnetic local time: ILAT-MLT) distributions. Since there were no direct comparisons of these in situ plasma measurements with highly resolving auroral images, as mentioned above, it is not obvious what types of auroral forms were associated with the electron signatures presented in these papers.…”

Section: Observations Of Auroral Arcs and Particlessupporting

confidence: 66%

Latitudinal Profiles of Auroral Forms/Motions and Plasma Properties Based on Simultaneous Image‐Particle Measurements by Reimei in the Midnight Auroral Oval

Hirahara,

Fukuda,

Ebihara

et al. 2024

JGR Space Physics

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We present the simultaneous and conjugated auroral emission and particle data obtained by a low‐altitude polar‐orbiting micro‐satellite, Reimei, for elucidating their latitudinal distributions and variations in the nightside auroral oval. Here are reported a few notable examples of the Reimei observations with high time and spatial resolutions, namely ∼120 msec. and ∼1.2 km × 1.2 km for multispectral auroral images and 40 msec. for energy‐pitch angle distributions of electrons and ions with energies of 10 eV–12 keV, respectively. The auroral images show various fine‐scale auroral activities characterized by the following types of auroral forms and variations: faint bands, streaming multiple arcs, shearing arcs, and vortices/curls, which are typical of the latitudinal properties of auroras. The particle analyzer simultaneously observed various properties of electron energy‐pitch angle and latitudinal distributions, and their temporal variations, each of which corresponds to a type of the auroral activities. Their features are summarized below. Reimei repetitively observed inverted‐V signatures of low‐energy (<1 keV) field‐aligned electrons in addition to the higher‐energy (several keV) diffuse electrons in low‐latitude auroral oval. In more active regions at higher latitudes, the dominant energy flux responsible for the multiple‐arc emissions was carried by the well‐known inverted‐V electron precipitation. The rapidly rotating vortices or so‐called curls of fine‐scale discrete auroras near the poleward boundary of the auroral oval were closely associated with the significant energy fluxes of spiky field‐aligned electron bursts with energy‐time dispersions produced by dispersive Alfvén waves.

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Section: Observations Of Auroral Arcs and Particlessupporting

confidence: 66%

Latitudinal Profiles of Auroral Forms/Motions and Plasma Properties Based on Simultaneous Image‐Particle Measurements by Reimei in the Midnight Auroral Oval

Hirahara,

Fukuda,

Ebihara

et al. 2024

JGR Space Physics

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“…The isotropic assumption is acceptable for the inverted‐V electron precipitation (Paschmann et al., 2002; J. Park et al., 2014). The other method estimates j ∥ based on the measurement of the cross‐track magnetic field perturbation (Δ B z ) by DMSP SSM with the assumption that the current sheets are infinitely long and perpendicular to the satellite track:

j_{∥}^{(normalB)} = \frac{1}{μ_{0} v} \frac{normalΔ B_{normalz}}{normalΔ t},

where μ 0 is the vacuum permeability, v the satellite velocity, and Δ t a time step of 5 s in our case.…”

Section: Methodsmentioning

confidence: 99%

“…where J N,e is the electron number flux integrated over all the energy channels measured by SSJ/5. The isotropic assumption is acceptable for the inverted-V electron precipitation (Paschmann et al, 2002;J. Park et al, 2014).…”

Section: Current-voltage Relationmentioning

confidence: 99%

DMSP Observations of High‐Latitude Dayside Aurora (HiLDA)

et al. 2021

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Reimei Satellite Observations of Alfvénic Interaction Modulating Inverted‐V Electrons and Filamentary Auroral Forms at the Poleward Edge of a Discrete Arc

Hirahara,

Ebihara,

Kitamura

et al. 2024

JGR Space Physics

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We present an event based on Reimei satellite observations in the low‐altitude midnight auroral region, showing that intense and clear energy‐dispersed electron precipitations, repetitively generated by field‐aligned accelerations due to dispersive Alfvén waves, were modulating inverted‐V electrons. These Alfvénic electrons had peak energies equal to or slightly larger than those of the inverted‐Vs and were associated with the filamentary auroral forms rapidly streaming at the poleward edge of a broad discrete arc. This arc was caused by the inverted‐V accompanied by ion depletions produced by quasi‐electrostatic parallel potential drop. Assuming instantaneous electron accelerations over a wide energy range in a single location and a simple time‐of‐flight effect for the energy‐time dispersions, the Alfvénic source distances were estimated 1,500 ± 500 km above the satellite altitude of ∼676 km, a lower bound since the interaction locations are realistically distributed in altitudinally extended regions. The electron characteristics in detailed energy‐pitch angle distributions obtained at high time resolution can be categorized into: (a) original inverted‐V fluxes energized by quasi‐electrostatic upward electric field, (b) accelerated and decelerated/reduced inverted‐V fluxes, (c) field‐aligned energy‐dispersed precipitations accelerated by dispersive Alfvén waves, and (d) upwelling secondary components effectively produced by the field‐aligned precipitations particularly at energies of a few tens of eV. This event is useful to reveal the interactions between the inverted‐V and Alfvénic electrons and their related ionospheric effects in the magnetosphere‐ionosphere coupling processes. The detailed energy‐pitch angle distributions presented here provide constraints for models of these interactions and processes.

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Characteristics of monoenergetic and broadband auroral electron precipitation as observed by the Science and Technology Satellite‐I

Cited by 3 publications

References 56 publications

Latitudinal Profiles of Auroral Forms/Motions and Plasma Properties Based on Simultaneous Image‐Particle Measurements by Reimei in the Midnight Auroral Oval

Latitudinal Profiles of Auroral Forms/Motions and Plasma Properties Based on Simultaneous Image‐Particle Measurements by Reimei in the Midnight Auroral Oval

DMSP Observations of High‐Latitude Dayside Aurora (HiLDA)

Reimei Satellite Observations of Alfvénic Interaction Modulating Inverted‐V Electrons and Filamentary Auroral Forms at the Poleward Edge of a Discrete Arc

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