Global observations of proton and electron auroras in a substorm

Mende, S. B.; Frey, H. U.; Lampton, M.; Gérard, Jean‐Claude; Hubert, Benoît; Fuselier, S. A.; Spann, James F.; Gladstone, R.; Burch, J. L.

doi:10.1029/2000gl012340

Cited by 40 publications

(36 citation statements)

References 15 publications

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“…The FAST satellite passes through this newly developed surge region at 1117, or 6 minutes after the start of the surge. Some substorm features described by Mende et al [2001] can be seen in this event. For example, the temporal and spatial coincidence of the initial proton intensification and poleward expansion with the electron auroras (not shown).…”

Section: Data Presentationmentioning

confidence: 63%

IMAGE FUV and in situ FAST particle observations of substorm aurorae

et al. 2003

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[1] Images from the IMAGE Wide-band Imaging Camera (WIC) and Spectrographic Imager (SI) channels SI-12 and SI-13 were compared to in situ data taken by FAST during several substorms. FAST spacecraft observations have shown that the high latitude auroral ionosphere has several distinct regions. Intense auroras are seen in regions of upward directed quasi static electric fields and of Alfven wave accelerated superthermal electrons. In two of the cases presented, the satellite passed through an active poleward propagating substorm surge on its duskward flank. Both show that the superthermal wave accelerated component to be on the polar cap boundary of the surge, and that it could be distinguished from quasi static field ''inverted V'' precipitation which occurred at the more equatorward parts of the auroral oval. In one of these cases, the surge was accompanied by intense ion outflow. Three cases showed the FAST satellite passing through the substorm aurora at midnight or the dawn side outside of the surge and the wave accelerated electrons were less clearly separated from the inverted V type precipitation. The wave accelerated electrons were seen to be part of very shortlived transient events, i.e., bursts. The region of auroral forms, associated with Alfven waves exhibit relatively soft auroral precipitation with very intense electron fluxes. By comparing the intensity of the WIC and SI-13 channels of IMAGE FUV, it is possible sometimes to distinguish optically between the two types of regions. Global imaging of the two regions would allow the separation of quasi-static plasma convection regions containing inverted V-s from regions of Alfven wave driven electrons signifying substorm related magnetic field dynamics.

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Section: Data Presentationmentioning

confidence: 63%

IMAGE FUV and in situ FAST particle observations of substorm aurorae

et al. 2003

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“…Consequently, the fractional proton contribution is minimum during the substorm most active phase. Mende et al [2001] showed the example of a substorm where the total electron precipitation suddenly increased one whole order of magnitude, while the protons increase only about 50%. The intensification of the precipitating electrons was relatively short‐lived (∼ 10 minutes) while the ENA enhancements, which are mostly indicative of the enhanced trapped particle population, are as long as an hour.…”

Section: Discussionmentioning

confidence: 99%

Total electron and proton energy input during auroral substorms: Remote sensing with IMAGE‐FUV

Hubert

Gérard

Evans³

et al. 2002

J. Geophys. Res.

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The IMAGE satellite carries three FUV imagers observing N2 LBH, O I 1356 Å, and HI Lyman α emissions in the polar aurora. These simultaneous observations are used to characterize the precipitating electron and proton energy fluxes. The proton energy flux is derived from the Lyman α measurements on the basis of efficiency curves calculated with a Monte Carlo simulation of the proton aurora. The resulting proton contribution to the N2 LBH and O I 1356 Å emissions is calculated and subtracted to obtain the electron contribution in the other two channels. These two quantities are used to determine the precipitating electron average energy and energy flux. The proton and electron energy fluxes are integrated over the hemisphere to obtain the rate of auroral energy dissipation (hemispheric power) carried by the protons and electrons separately. The time development of the proton and electron aurora during four winter time events is examined. Although the onsets of the proton and electron aurora coincide in time and space, the time of the peak of energy dissipation and the recovery time are often found to differ. The fractional energy flux carried by the protons is highest during quiet periods and reaches a minimum during the most active phase of the substorms. This result is in agreement with the dependence of the fractional proton hemispheric power on magnetic activity measured by NOAA 15. The hemispheric power deduced from the FUV images is compared to the NOAA‐deduced values and found to be in reasonable agreement. Sources of uncertainties in the determination of the hemispheric power are discussed on the basis of several sensitivity tests. In particular, it is found that the most critical factor is the assumption made on the energy of the auroral protons if this energy is <25 keV.

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“…Higherenergetic particles with the large pitch angles can also give a contribution to the maximum of the hydrogen line profile, but this contribution is much weaker because of the decrease in excitation efficiency at the larger energies (>20 keV). Besides, in some papers, the dependence of the efficiency of hydrogen emission excitation on initial proton energy is ignored (for example, Mende et al (2001)). …”

Section: Modelling Of the Degradation Of The Proton-h Atom Fluxmentioning

confidence: 99%

“…Using global observations of electron and proton produced auroras observed by IMAGE satellite FUV instruments, Mende et al (2001) concluded that the peak intensity of the proton aurora did not change substantially during substorms. They found that the initial brightening of the substorm was embedded in proton precipitation, which coincides with the results of Samson et al (1992).…”

Section: Introductionmentioning

confidence: 99%

Variations of auroral hydrogen emission near substorm onset

et al. 2005

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Abstract. The results of coordinated optical ground-based observations of the auroral substorm on 26 March 2004 in the Kola Peninsula are described. Imaging spectrograph data with high spectral and temporal resolution recorded the Doppler profile of the Hα hydrogen emission; this allows us to estimate the average energy of precipitating protons and the emission intensity of the hydrogen Balmer line. Two different populations of precipitating protons were observed during an auroral substorm. The first of these is associated with a diffuse hydrogen emission that is usually observed in the evening sector of the auroral oval and located equatorward of the discrete electron arcs associated with substorm onset. The average energy of the protons during this precipitation was ∼20-35 keV, and the energy flux was ∼3×10 −4 Joule/m 2 s. The second proton population was observed 1-2 min after the breakup during 4-5 min of the expansion phase of substorm into the zone of bright, discrete auroral structures (N-S arcs). The average energy of the protons in this population was ∼60 keV, and the energy flux was ∼2.2×10 −3 Joule/m 2 s. The observed spatial structure of hydrogen emission is additional evidence of the higher energy of precipitated protons in the second population, relative to the protons in the diffuse aurora. We believe that the most probable mechanism of precipitation of the second population protons was pitch-angle scattering of particles due to non-adiabatic motion in the region of local dipolarization near the equatorial plane.

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Global observations of proton and electron auroras in a substorm

Cited by 40 publications

References 15 publications

IMAGE FUV and in situ FAST particle observations of substorm aurorae

IMAGE FUV and in situ FAST particle observations of substorm aurorae

Total electron and proton energy input during auroral substorms: Remote sensing with IMAGE‐FUV

Variations of auroral hydrogen emission near substorm onset

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