The GEOTAIL Magnetic Field Experiment.

Kokubun, S.; Yamamoto, T.; Acuña, M. H.; Hayashi, K.; Shiokawa, K.; Kawano, Hideaki

doi:10.5636/jgg.46.7

Cited by 678 publications

(448 citation statements)

References 14 publications

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“…Following injection A1, open magnetic flux is closed, shrinking the polar cap, and the dayside reconnection rate is insufficient to return the flux to the pre-substorm level before the next expansion onset. Huang et al (2003b) identified injection A1 as a substorm through observations by GEOTAIL (Kokubun et al, 1994) of a travelling compression region related to plasmoid formation in the magnetotail as well as observations of proton flux enhancements by 1991-080 (16:00 MLT).…”

Section: Overviewmentioning

confidence: 99%

Energetic electron precipitation during sawtooth injections

Kavanagh

Donovan

et al. 2007

Ann. Geophys.

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Abstract. We present simultaneous riometer observations of cosmic noise absorption in the nightside and dawn-noon sectors during sawtooth particle injections during 18 April 2002. Energetic electron precipitation (>30 keV) is a feature of magnetospheric substorms and cosmic radio noise absorption acts as a proxy for qualitatively measuring this precipitation. This event provides an opportunity to compare the absorption that accompanies periodic electron injections with the accepted paradigm of substorm-related absorption. We consider whether the absorption is consistent with the premise that these injections are quasi-periodic substorms and study the effects of sustained activity on the level of precipitation. Four consecutive electron injection events have been identified from the LANL (Los Alamos National Laboratory) geosynchronous data; the first two showing that additional activity can occur within the 2-4 h sawtooth periodicity. The first three events have accompanying absorption on the nightside that demonstrate good agreement with the expected pattern of substorm-absorption: discrete spike events with poleward motion at the onset followed by equatorward moving structures and more diffuse absorption, correlated with optical observations. Dayside absorption is linked to gradient-curvature drifting electrons observed at geostationary orbit and it is shown that low fluxes can lead to a lack of absorption as precipitation is suppressed; precipitation begins when the drifting electron flux surpasses some critical level following continuous injections of electrons from the magnetotail. In addition it is shown that the apparent motion of absorption determined from an azimuthal chain of riometers exhibits an acceleration that may be indicative of an energisation of the drifting electron population.

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Section: Overviewmentioning

confidence: 99%

Energetic electron precipitation during sawtooth injections

Kavanagh

Donovan

et al. 2007

Ann. Geophys.

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“…The 12 s resolution data from Geotail magnetometer [Kokubun et al, 1994] and the low-energy particle (LEP) experiment [Mukai et al, 1994] have been collected from 1998 to 2005. The LEP data on Geotail are over the energy range of several eV to 43 keV.…”

Section: Data Descriptionmentioning

confidence: 99%

X lines in the magnetotail for southward and northward IMF conditions

et al. 2015

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Utilizing associated observations of Geotail and ACE satellites from the year of 1998 to 2005, we investigated the X lines in the near‐Earth tail under different interplanetary magnetic field (IMF) conditions. The X lines are recognized by the tailward fast flows with negative Bz. Statistically, the X lines in the tail can be observed for southward as well as northward IMF, but more frequently observed for southward IMF. A typical case on 26 April 2005 showed clear evidence that the X line can occur for northward IMF while the geomagnetic activity is particularly quiet. Further analysis showed that the X line‐related solar wind has stronger Ey and Bz components for southward than northward IMF. In addition, the X line‐related geomagnetic activities are stronger for southward than northward IMF.

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“…The intervals are 16:00±19:30 UT on 14 March (day 73) 1993, and 08:28±08:43 and 14:25±14:45 UT on 18 April (day 108) 1994. We used data from the magnetic-®eld (MGF) experiment (Kokubun et al, 1994) at 3-s resolution and the energetic particle (EPIC) instrument (Williams et al, 1994). EPIC consists of sensors ICS and STICS, and the time resolution is declared in each plot varying from 3 to 96 s. All the EPIC measurements are depicted as di erential¯uxes.…”

Section: Observations and Data Analysismentioning

confidence: 99%

Spatial structure of the plasma sheet boundary layer at distances greater than 180 R<sub>E</sub> as derived from energetic particle measurements on GEOTAIL

et al. 1997

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Abstract. We have analyzed the onsets of energetic particle bursts detected by the ICS and STICS sensors of the EPIC instrument on board the GEOTAIL spacecraft in the deep magnetotail (i.e., at distances greater than 180 R E ). Such bursts are commonly observed at the plasma-sheet boundary layer (PSBL) and are highly collimated along the magnetic ®eld. The bursts display a normal velocity dispersion (i.e., the higher-speed particles are seen ®rst, while the progressively lower speed particles are seen later) when observed upon entry of the spacecraft from the magnetotail lobes into the plasma sheet. Upon exit from the plasma sheet a reverse velocity dispersion is observed (i.e., lower-speed particles disappear ®rst and higher-speed particles disappear last). Three major ®ndings are as follows. First, the tailwardjetting energetic particle populations of the distant-tail plasma sheet display an energy layering: the energetic electrons stream along open PSBL ®eld lines with peak uxes at the lobes. Energetic protons occupy the next layer, and as the spacecraft moves towards the neutral sheet progressively decreasing energies are encountered systematically. These plasma-sheet layers display spatial symmetry, with the plane of symmetry the neutral sheet. Second, if we consider the same energy level of energetic particles, then the H + layer is con®ned within that of the energetic electron, the He ++ layer is con®ned within that of the proton, and the oxygen layer is con®ned within the alpha particle layer. Third, whenever the energetic electrons show higher¯uxes inside the plasma sheet as compared to those at the boundary layer, their angular distribution is isotropic irrespective of the Earthward or tailward character of¯uxes, suggesting a closed ®eld line topology.

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The GEOTAIL Magnetic Field Experiment.

Cited by 678 publications

References 14 publications

Energetic electron precipitation during sawtooth injections

Energetic electron precipitation during sawtooth injections

X lines in the magnetotail for southward and northward IMF conditions

Spatial structure of the plasma sheet boundary layer at distances greater than 180 R<sub>E</sub> as derived from energetic particle measurements on GEOTAIL

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The GEOTAIL Magnetic Field Experiment.

Cited by 678 publications

References 14 publications

Energetic electron precipitation during sawtooth injections

Energetic electron precipitation during sawtooth injections

X lines in the magnetotail for southward and northward IMF conditions

Spatial structure of the plasma sheet boundary layer at distances greater than 180 R&lt;sub&gt;E&lt;/sub&gt; as derived from energetic particle measurements on GEOTAIL

Contact Info

Product

Resources

About

Spatial structure of the plasma sheet boundary layer at distances greater than 180 R<sub>E</sub> as derived from energetic particle measurements on GEOTAIL