Estimating high-energy electron fluxes by intercalibrating Reimei optical and particle measurements using an ionospheric model

Whiter, Daniel; Lanchester, B. S.; Sakanoi, Takeshi; Asamura, Kazushi

doi:10.1016/j.jastp.2012.06.014

Cited by 11 publications

(6 citation statements)

References 14 publications

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“…In fact, electron data show the inverted-V electron precipitation with widths of ∼100 km corresponding to the auroral band structure. In the poleward half of the inverted-V structure where the small-scale auroral arcs appeared, there are small-scale fluctuations of the peak energies of electrons in the energy range of several keV, with time-dispersed low-energy electrons precipitating simultaneously, implying the existence of Alfvén wave acceleration (Whiter et al 2012). It was concluded from this event that the small-scale auroral arcs are not generated by a single acceleration mechanism but produced by the fluctuations of peak energy of inverted-V type accelerated electrons as caused by the interaction of Alfvén waves.…”

Section: Introductionmentioning

confidence: 99%

Small-Scale Dynamic Aurora

et al. 2021

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Small-scale dynamic auroras have spatial scales of a few km or less, and temporal scales of a few seconds or less, which visualize the complex interplay among charged particles, Alfvén waves, and plasma instabilities working in the magnetosphere-ionosphere coupled regions. We summarize the observed properties of flickering auroras, vortex motions, and filamentary structures. We also summarize the development of fundamental theories, such as dispersive Alfvén waves (DAWs), plasma instabilities in the auroral acceleration region, ionospheric feedback instabilities (IFI), and the ionospheric Alfvén resonator (IAR).

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Section: Introductionmentioning

confidence: 99%

Small-Scale Dynamic Aurora

et al. 2021

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“…The intensity of the N 2 670.5 nm emission was estimated from the N 2 first positive band based on the result of Whiter et al . []. The all‐sky camera and photometer showed that aurora activity over PFRR increased once around 1040 UT; however, it did not develop into an aurora breakup.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 1 (ninth panel) shows auroral intensity variations for the wavelengths of the N 2 first positive band (650-700 nm), N 2 emission line at 670.5 nm, and atomic oxygen emission line at 844.6 nm emission. The intensity of the N 2 670.5 nm emission was estimated from the N 2 first positive band based on the result of Whiter et al [2012]. The all-sky camera and photometer showed that aurora activity over PFRR increased once around 1040 UT; however, it did not develop into an aurora breakup.…”

Section: Event Descriptionmentioning

confidence: 99%

Substructures with luminosity modulation and horizontal oscillation in pulsating patch: Principal component analysis application to pulsating aurora

et al. 2016

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We observed a mesoscale aurora (100 km × 100 km) with patchy structure and equatorward propagation at Poker Flat Research Range on 1 December 2011. Fast Fourier transform (FFT) analysis revealed that this pulsating patch clearly exhibited temporal variations that can be categorized into two types: on‐off pulsation (7.8–10 s) with large amplitudes and luminosity modulations excited during on phase with a frequency of about 3.0 Hz. In addition, we applied principal component analysis (PCA) to time series image data of the pulsating aurora for the first time. Time coefficients were estimated by PCA for the whole patch and the substructures were consistent with those obtained from the FFT analysis, and therefore, we concluded that PCA is capable of decomposing several structures that have different coherent spatiotemporal characteristics. Another new insight in this study is that the rapid variations were highly localized; they were excited in only the substructures embedded in the whole structure. Moreover, the whole patch propagated equatorward because of E × B drift of cold plasma, while the substructures did not show such systematic propagation but rather forward‐backward oscillations. The horizontal scale of the substructures was estimated to be no smaller than 410 km at the magnetic equator, which is comparable to that of the wave packet structure of a whistler mode chorus perpendicular to the field line. We suggest that the apparent horizontal oscillation of the substructures is associated with field‐aligned propagations of the whistler mode chorus in a duct.

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“…More quantitative comparisons between the data of Reimei MAC and ESA were shown by Whiter et al. (2012). The net upward field‐aligned current [A] during these successive arcs was also the largest since the latitudinal distribution of the multiple auroras was the widest while the current density [A/m] was not the largest, as shown in Figure 1a and 1 g/hr.…”

Section: Discussionmentioning

confidence: 81%

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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Estimating high-energy electron fluxes by intercalibrating Reimei optical and particle measurements using an ionospheric model

Cited by 11 publications

References 14 publications

Small-Scale Dynamic Aurora

Small-Scale Dynamic Aurora

Substructures with luminosity modulation and horizontal oscillation in pulsating patch: Principal component analysis application to pulsating aurora

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

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