Auroral particle instrument onboard the index satellite

Asamura, Kazushi; Tsujita, Daisuke; Tanaka, Hidema; Saito, Y.; Mukai, T.; Hirahara, Masafumi

doi:10.1016/s0273-1177(03)90275-4

Cited by 43 publications

(32 citation statements)

References 9 publications

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“…It should be noted that these electron energy estimates are preliminary and that there could be systematic errors of up to a factor of 2 in the calculated energies. However the electron energies calculated are consistent with the precipitating electron energies that are typically measured in situ by electron spectrometers, for example on the FAST (Fast Auroral Snapshot Explorer) satellite (Carlson et al, 1998;McFadden et al, 1999) and on the Reimei satellite (Asamura et al, 2003(Asamura et al, , 2009, which adds a level of confidence to these estimates.…”

Section: Electron Energysupporting

confidence: 78%

Characteristics of Poker Flat Incoherent Scatter Radar (PFISR) naturally enhanced ion-acoustic lines (NEIALs) in relation to auroral forms

2014

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Abstract. Naturally enhanced ion-acoustic lines (NEIALs) have been observed with the Poker Flat Incoherent Scatter Radar (PFISR) ever since it began operating in 2006. The nearly continuous operation of PFISR since then has led to a large number of NEIAL observations from there, where common-volume, high-resolution auroral imaging data are available. We aim to systematically distinguish the different types of auroral forms that are associated with different NEIAL features, including spectral shape and altitude extent. We believe that NEIALs occur with a continuum of morphological characteristics, although we find that most NEIALs observed with PFISR fall into two general categories. The first group occurs at fairly low altitudes -F region or below -and have power at, and spread between, the ion-acoustic peaks. The second group contains the type of NEIALs that have previously been observed with the EIS-CAT radars, those that extend to high altitudes (600 km or more) and often have large asymmetries in the power enhancements between the two ion-acoustic shoulders. We find that there is a correlation between the auroral structures and the type of NEIALs observed, and that the auroral structures present during NEIAL events are consistent with the likely NEIAL generation mechanisms inferred in each case. The first type of NEIAL -low altitude -is the most commonly observed with PFISR and is most often associated with active, structured auroral arcs, such as substorm growth phase, and onset arcs and are likely generated by Langmuir turbulence. The second type of NEIAL -high altitude -occurs less frequently in the PFISR radar and is associated with aurora that contains large fluxes of low-energy electrons, as can happen in poleward boundary intensifications as well as at substorm onset and is likely the result of current-driven instabilities and in some cases Langmuir turbulence as well. In addition, a preliminary auroral photometry analysis revealed that there is an anticorrelation between the altitude of the NEIALs and the calculated energy of the electrons, which is consistent with the hypotheses presented here regarding generation mechanisms.

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Section: Electron Energysupporting

confidence: 78%

Characteristics of Poker Flat Incoherent Scatter Radar (PFISR) naturally enhanced ion-acoustic lines (NEIALs) in relation to auroral forms

2014

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“…It contains high resolution, 40 ms per spectra with 32 energy steps, ion and electron spectrometers covering the range of 12 eV to 12 keV (Asamura et al, 2003). The velocity of Reimei is approximately 9 km/s, resulting in a spatial resolution of 380 m, which is less than the spatial resolution of the imager, thus not affecting the comparisons.…”

Section: Methodsmentioning

confidence: 99%

Ground-based observations of diffuse auroral structures in conjunction with Reimei measurements

et al. 2010

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Abstract. We present results from ground-based auroral observations coordinated with the Japanese satellite, Reimei, that took place during the winters of 2006, 2007 and 2008 at Poker Flat, Alaska. Comparable temporal and spatial resolution for the optical and in situ particle data, allowed for investigation of small scale and/or rapidly time-varying auroral structures. Four satellite passes through diffuse auroral structures were identified. The structures within the aurora, whether stationary or time-varying (pulsating aurora), were most closely correlated with the highest energy precipitating electrons measured by these detectors (8 to 12 keV). This relation is found to be consistent across all four examples, revealing that the electron precipitation responsible for these diffuse auroral structures is primarily that of the ≥8 keV electrons.

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“…We also show the sensitivity to the procedure in Figure 10. The Reimei satellite is also in a Sun-synchronous polar orbit but at ∼650 km altitude, with higher time resolution, 40 ms per spectra with 32 energy steps, ion, and electron spectrometers covering the range of 12 eV to 12 keV [Asamura et al, 2003]. The velocity of the DMSP satellites is approximately 7.4 km/s, resulting in a spatial resolution of about 7.4 km for the DMSP electron measurements-which is larger than the imagers' spatial resolution-therefore putting a limit on the spatial scale of the pulsating auroral comparisons.…”

Section: Satellitementioning

confidence: 99%

Low‐altitude satellite measurements of pulsating auroral electrons

2015

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We present observations from the Defense Meteorological Satellite Program and Reimei satellites, where common‐volume high‐resolution ground‐based auroral imaging data are available. These satellite overpasses of ground‐based all‐sky imagers reveal the specific features of the electron populations responsible for different types of pulsating aurora modulations. The energies causing the pulsating aurora mostly range from 3 keV to 20 keV but can at times extend up to 30 keV. The secondary, low‐energy electrons (<1 keV) are diminished from the precipitating distribution when there are strong temporal variations in auroral intensity. There are often persistent spatial structures present inside regions of pulsating aurora, and in these regions there are secondary electrons in the precipitating populations. The reduction of secondary electrons is consistent with the strongly temporally varying pulsating aurora being associated with field‐aligned currents and hence parallel potential drops of up to 1 kV.

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Auroral particle instrument onboard the index satellite

Cited by 43 publications

References 9 publications

Characteristics of Poker Flat Incoherent Scatter Radar (PFISR) naturally enhanced ion-acoustic lines (NEIALs) in relation to auroral forms

Characteristics of Poker Flat Incoherent Scatter Radar (PFISR) naturally enhanced ion-acoustic lines (NEIALs) in relation to auroral forms

Ground-based observations of diffuse auroral structures in conjunction with Reimei measurements

Low‐altitude satellite measurements of pulsating auroral electrons

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