The May 2‐3, 1986 magnetic storm: First energetic ion composition observations with the Mics instrument on Viking

Stüdemann, W.; Wilken, B.; Kremser, G.; Korth, A.; Fennell, J. F.; Blake, B.; Koga, R.; Hall, D. S.; Bryant, D. A.; Søraas, F.; Brønstad, K.; Fritz, T. A.; Lundin, R.; Gloeckler, G.

doi:10.1029/gl014i004p00455

Cited by 23 publications

(10 citation statements)

References 7 publications

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“…[13] During storm intervals, a dawn-dusk asymmetry is often observed in the ion temperature images with the dawn side of the magnetosphere being cooler than the dusk side. Similar asymmetries in the ring current ion temperatures during storm times have been reported from in-situ measurements [Studemann et al, 1987]. Hints of a storm time dawn-dusk asymmetry in energetic neutral atom fluxes were also suggested in a modeling study of neutral atom emission observed by ISEE 1 [Roelof, 1987].…”

Section: Discussionsupporting

confidence: 62%

Remote ion temperature measurements of Earth's magnetosphere: Medium energy neutral atom (MENA) images

Scime

Keesee

Jahn

et al. 2002

Geophysical Research Letters

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[1] Energy spectra of ENA images obtained with the MENA imager on the IMAGE observatory are used to construct remote images of the plasma ion temperature. The remotely measured ion temperatures are consistent with in-situ ion temperature measurements. During the storm of August 12, 2000, the ion temperatures on the dawn side of the magnetosphere are significantly lower than the dusk side ion temperatures. Similar observations of ion temperature asymmetry are presented for three other storm periods.

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Section: Discussionsupporting

confidence: 62%

Remote ion temperature measurements of Earth's magnetosphere: Medium energy neutral atom (MENA) images

Scime

Keesee

Jahn

et al. 2002

Geophysical Research Letters

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“…Finally, the composition and energy per charge of ions from to to 326 keV Ie were recorded, using the magnetospheric ion com position spectrometer (MICS) [Stiidemann et al , 1987]. Pitch angle distributions were obtained for orbits 1103 and 893 by averaging over lO-min time periods to obtain adequate statistics.…”

Section: Eqmentioning

confidence: 99%

Viking magnetic and electric field observations of Pc 1 waves at high latitudes

Erlandson¹,

Zanetti²,

Potemra³

et al. 1990

J. Geophys. Res.

121

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Magnetic and electric field fluctuations in the Pc 1 frequency range (0.2-5 Hz) have been observed by the polar-orbiting Viking satellite. The fluctuations, interpreted here as electromagnetic ion cyclotron (EMIC) waves, were observed during 21 of 450 orbits surveyed between 0900 and 1400 MLT, near 3 RE geocentric altitude, and at invariant latitudes from 59° to 77°. The frequency structure of the waves is investigated, using spectral analysis and by determining the distribution of the wave frequency as a function of invariant latitude. At in variant latitudes from 59° to 72°, EMIC waves were observed in the frequency range below the equatorial He + gyrofrequency, while from 70° to 77° invariant latitude, EMIC waves were observed in the frequency range above the equatorial He + gyrofrequency. This latitude structure of the wave frequency is discussed in terms of the linear growth rate dependence of the waves on the heavy ion density, ion anisotropy, and ion energy. The propagation characteristics of these waves were also investigated, using minimum variance analy sis and polarization analysis, and by estimating the Poynting flux based on the observed magnetic and electric field. The waves had Poynting vectors directed downward toward Earth and reached magnitudes between 0.01 and 0.1 erg/cm2 s. The polarization of the waves was found to vary between linear, left-hand, and right-hand as a function of time or latitude. This variation is interpreted as the structure of spatially localized Pc 1 waves at high latitudes above the ionosphere.

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“…So far, in situ satellite observations have shown that a majority of the storm‐time enhancement of the tens‐of‐keV ion flux is in the premidnight sector. Stüdemann et al [1987] have shown that during the 2–3 May 1986 storm ( Dst minimum of −79 nT), the proton flux with 10–206 keV/q measured by the Viking satellite dramatically increased on the duskside (∼1800 MLT), while the proton spectrum was very similar to the quiet‐time one on the dawnside (∼0600 MLT). Similarly, during the main phase of the 10–11 April 1997 storm ( Dst minimum of −82 nT), a significant increase in the ion flux in the 30–80 keV energy range was also observed on the duskside (∼2000 MLT) by NOAA 12, while the flux remains almost steady on the dawnside (∼0800 MLT) [ Ebihara and Ejiri , 2000].…”

Section: Introductionmentioning

confidence: 99%

Postmidnight storm‐time enhancement of tens‐of‐keV proton flux

Ebihara

Fok

2004

J. Geophys. Res.

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[1] We investigated the global morphology of the storm-time distribution of ring current protons and energetic neutral atoms (ENAs) observed by the High-Energy Neutral Atom (HENA) imager on the IMAGE satellite. The postmidnight enhancements of the proton and ENA fluxes were in particular focused on in this study, and the following six possible mechanisms causing the postmidnight enhancements were tested by using a self-consistent kinetic simulation of the ring current protons: (1) shielding electric field, (2) gap between the region 2 field-aligned current and the auroral oval, (3) strong gradient of the ionospheric conductivity near the terminator, (4) plasma sheet density, (5) plasma sheet temperature, and (6) local-time dependence of the plasma sheet density. When the ring current is self-consistently coupled with the ionosphere through the region 2 field-aligned current, the simulated postmidnight enhancements are found to agree well with the IMAGE/HENA observations, even though effects other than shielding fields were not included. The overall convection strength is found to have a substantial influence on the morphology of the distribution of the ring current protons. The MLT of the flux peak is also shown to depend slightly on the plasma sheet density and solar activity. A local-time dependence of the plasma sheet density can produce a pronounced postmidnight enhancement without introducing the self-consistent electric field. Other possible mechanisms causing the postmidnight enhancements are also discussed in detail.

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The May 2‐3, 1986 magnetic storm: First energetic ion composition observations with the Mics instrument on Viking

Cited by 23 publications

References 7 publications

Remote ion temperature measurements of Earth's magnetosphere: Medium energy neutral atom (MENA) images

Remote ion temperature measurements of Earth's magnetosphere: Medium energy neutral atom (MENA) images

Viking magnetic and electric field observations of Pc 1 waves at high latitudes

Postmidnight storm‐time enhancement of tens‐of‐keV proton flux

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