Rocket observation of the magnetosphere‐ionosphere coupling processes in quiet and active arcs

Shiokawa, K.; Fukunishi, H.; Yamagishi, Hisakazu; Miyaoka, Hiroshi; Fujii, Ryoichi; Tohyama, Fumio

doi:10.1029/ja095ia07p10679

Cited by 20 publications

(17 citation statements)

References 23 publications

(15 reference statements)

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“…Weimer et al (1987) DE-1 satellite 11 000−13 000 km The magnetic perturbation derived from the model agrees with that measured by the magnetometer. * Shiokawa et al (1990) S-310 Rocket ∼200 km KV (from particle) agrees with J (from magnetometer). * Lu et al (1991) DE-1, 2 satellite 11 000−13, 000 km, 660−800 km KV (from particle) agrees with J (from magnetometer).…”

Section: Instrumentmentioning

confidence: 79%

Current-voltage relationship in the auroral particle acceleration region

Mukai

Fukunishi

2004

Ann. Geophys.

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Abstract. The current-voltage relationship in the auroral particle acceleration region has been studied statistically by the Akebono (EXOS-D) satellite in terms of the charge carriers of the upward field-aligned current. The Akebono satellite often observed field-aligned currents which were significantly larger than the model value predicted by Knight (1973). We compared the upward field-aligned current estimated by three different methods, and found that low-energy electrons often play an important role as additional current carriers, together with the high-energy primary electrons which are expected from Knight's relation. Such additional currents have been observed especially at high and middle altitudes of the particle acceleration region. Some particular features of electron distribution functions, such as "cylindrical distribution functions" and "electron conics", have often been observed coinciding with the additional currents. They indicated time variability of the particle acceleration region. Therefore, we have concluded that the low-energy electrons within the "forbidden" region of electron phase space in the stationary model often contribute to charge carriers of the current because of the rapid time variability of the particle acceleration region. "Cylindrical distribution functions" are expected to be found below the time-varying potential difference. We statistically examined the locations of "cylindrical distribution function", and found that their altitudes are related to the location where the additional currents have been observed. This result is consistent with the idea that the lowenergy electrons can also carry significant current when the acceleration region changes in time.

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Section: Instrumentmentioning

confidence: 79%

Current-voltage relationship in the auroral particle acceleration region

Mukai

Fukunishi

2004

Ann. Geophys.

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“…Evans [] showed that the results from this model were in very good agreement with precipitating electron flux results from the Injun 5 satellite. This method, which uses an accelerated Maxwellian distribution function to describe the precipitating auroral electron flux, has been applied to many observations by satellites and rockets [ Burch et al , ; Winningham et al , ; Pulliam et al , ; Mallinckrodt , ; Reiff et al , ; Shiokawa and Fukunishi , ; Shiokawa et al , ; Olsson and Janhunen , ; Shiokawa et al , ]. However, very few studies have validated the quasi‐trapped electron flux predicted by the Evans [] model [ Winningham et al , ; Pulliam et al , ].…”

Section: Introductionmentioning

confidence: 99%

“…It has been applied to the Lyons [] model of auroral electrodynamics, which coupled the magnetosphere and the ionosphere [ Lyons , ; Kletzing et al , ]. The current‐voltage relation has been applied to sounding rocket data [ Lyons et al , ; Bruening and Goertz , ; Shiokawa et al , ; Kletzing et al , ], and many satellite observations, such as the Dynamics Explorer mission [ Weimer et al , ; Lu et al , ], FREJA [ Olsson et al , ], Fast Auroral Snapshot Explorer [ Elphic et al , ], and Defense Meteorological Satellite Program (DMSP) [ Shiokawa and Fukunishi , ; Shiokawa et al , ].…”

Section: Introductionmentioning

confidence: 99%

Observations in the E region ionosphere of kappa distribution functions associated with precipitating auroral electrons and discrete aurorae

et al. 2014

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Precipitating auroral electrons can produce discrete auroral arcs that contain signatures of the magnetospheric auroral source region. Differential number flux observations over two discrete aurorae were obtained by the Auroral Currents and Electrodynamics Structure sounding rocket mission, which successfully launched in 2009. These observations were made at E region altitudes of approximately 130 km. A model of precipitating auroral electrons as described by Evans (1974) was fit to the electron differential number flux obtained by the payloads, and parameters from the model were used to infer properties of the auroral source region. It is shown that the field-aligned precipitating electrons were better fit by a kappa distribution function versus a Maxwellian distribution function for the equatorward side of the first, quasi-stable, auroral arc crossing. The latter half of the first auroral arc crossing and second auroral crossing show that the precipitating electrons were better fit by a Maxwellian distribution function, which provides additional observational confirmation of previous studies. The low-energy electron population determined by the Evans (1974) model was within a factor of 2 of the observed differential number flux. The source region parameters determined from fitting the model to the data were compared with relevant studies from sounding rockets and satellites. Our observations are consistent with the results of Kletzing et al. (2003) that the plasma sheet electrons mapping to auroral zone invariant latitudes are characterized by kappa distribution functions.

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“…A great number of rocket and satellite observations have investigated the energy spectra of auroral particles [ Arnoldy and Choy , 1973; Arnoldy et al , 1974, 1985; Meng , 1976; Lui et al , 1977; Meng et al , 1979; Lin and Hoffman , 1979; Ejiri et al , 1988; Shiokawa et al , 1990; Frahm et al , 1997]. These in situ observations demonstrated that the energy spectra strongly depend on the auroral type and/or phase of the substorm.…”

Section: Introductionmentioning

confidence: 99%

Spectral type of auroral precipitating electrons estimated from optical and cosmic noise absorption measurements

et al. 2006

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[1] We estimate the energy spectra of precipitating electrons from optical emissions and cosmic noise absorption (CNA) that were observed with the all-sky imager (ASI) and the 16 Â 16-element imaging riometer at Poker Flat Research Range (PFRR) (65.11°N, 147.42°W), Alaska. Maxwellian energy parameters (peak energy and total energy flux) are derived from the auroral spectroscopic emissions according to the conventional photometric method. We theoretically estimate CNA from the derived Maxwellian spectra and compare it with the observed CNA. The difference between the estimated CNA and the observed (dCNA) is used as an indicator of the difference in high-energy electron flux (E > $20 keV) between the actual energy distribution and Maxwellian. This analysis is carried out for two substorm events in the evening sector to show the temporal and spatial variations of the energy spectra. Event 1 exhibits two arcs of CNA during the growth phase of the substorm. The results for this event suggest that the energy spectra of the two CNA arcs have different shapes, and this difference is revealed in the precipitating electron flux quasi-simultaneously measured by NOAA-17. Event 2 is a typical substorm that consists of growth, expansion, and recovery phases. The dCNA changes throughout the course of the substorm, which can be consistently explained by the energy spectrum variation of the precipitating electrons measured in previous studies. Furthermore, the energy spectra consistent for both optical and CNA data are estimated by assuming a kappa or a Gaussian distribution. This estimation method based on ground observations of the energy spectra has the potential to provide significant information on substorms.

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Rocket observation of the magnetosphere‐ionosphere coupling processes in quiet and active arcs

Cited by 20 publications

References 23 publications

Current-voltage relationship in the auroral particle acceleration region

Current-voltage relationship in the auroral particle acceleration region

Observations in the E region ionosphere of kappa distribution functions associated with precipitating auroral electrons and discrete aurorae

Spectral type of auroral precipitating electrons estimated from optical and cosmic noise absorption measurements

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