Correlation of High- and Low-Law-Latitude Pi 2 Magnetic Pulsations Observed at 210.DEG. Magnetic Meridian Chain Stations.

Yumoto, K.; Osaki, Hiroshi; Fukao, K.; Shiokawa, K.; Tanaka, Yoshihito; Solovyev, S. I.; Krymskij, G. F.; Vershinin, E. F.; Osinin, V. F.

doi:10.5636/jgg.46.925

Cited by 31 publications

(40 citation statements)

References 32 publications

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“…Since these pulsations at 1004 UT had coherent phase structures at the three stations, we conclude that this was a Pi 2 pulsation that occurred nearly simultaneously on a global scale. The out-of-phase characteristics of the pulsation at 1004 UT between CHD and the three low-latitude stations are also consistent with the Pi 2 characteristics reported by Yumoto et al (1994). The MCQ station, which was in the auroral zone in the southern hemisphere, slightly nightside of TIX, observed a small negative-H change at 1004 UT, while the TIX station observed a small positive-H change at 1004 UT.…”

Section: Summary and Discussionsupporting

confidence: 78%

Simultaneous DMSP, all-sky camera, and IMAGE FUV observations of the brightening arc at a substorm pseudo-breakup

et al. 2007

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Auroral particles, field-aligned currents, and plasma convections in the vicinity of the brightening arc at substorm onset are still not well understood, since it is very rare to have conjugate satellite measurements above the brightening arc. In this paper, we investigate the characteristics of auroral particles and fields associated with the brightening arc at a pseudo-onset of substorm on October 31, 2000, using ground all-sky TV images, IMAGE FUV auroral images, and particle, magnetic field, and plasma flow data obtained by the DMSP F12 satellite. The arc brightening at Tixie (66.0• MLAT), Russia, occurred at 1004 UT (18.75 MLT) coincident with a coherent Pi 2 pulsation at midlatitudes and with the DMSP crossing above the arc. The brightening arc did not develop on a global scale, indicating that this event is a pseudo auroral breakup, which occurred ∼16 min before the major substorm expansion onset. IMAGE auroral images indicate that the longitude of the brightening center was ∼2.5 h nightside of Tixie. The DMSP data show that the precipitating particles associated with the brightening arc correspond to an electron inverted-V structure at the equatorward edge of the electron precipitation region. The arc was located in the energetic (>1 keV) ion precipitation region, near the equatorward boundary of the upward region 1 field-aligned current, and at the peak of the sunward convection velocity. These facts indicate that the brightening arc at duskside of the onset local time was located in the inner plasma sheet at the inner edge of the region 1 current source in the sunward convection region.

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Section: Summary and Discussionsupporting

confidence: 78%

Simultaneous DMSP, all-sky camera, and IMAGE FUV observations of the brightening arc at a substorm pseudo-breakup

et al. 2007

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“…(21)). This might cause a n 180° phase shift in the H component of Pi2 pulsation around the plasmapause (Fukunishi, 1975;Lester and Orr, 1983;Yumoto et al, 1994). Figure 1 is a schematic illustration for the excitation of shear Alfven wave (bill) around the magnetic equator in the northern hemisphere by the earthward propagating compressional wave.…”

Section: Discussionmentioning

confidence: 99%

The Excitation of Shear Alfven Wave and the Associated Modulation of Compressional Wave in the Inner Magnetosphere.

Itonaga

Yoshikawa

1996

J. geomagn. geoelec

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Two basic but novel equations directly describing the generation of shear Alfven and compressional waves in the inner magnetosphere filled with a cold magnetized plasma are derived. The shear Alfven wave is characterized by the field-aligned current and the compressional wave by the compressional component of the magnetic field. Such a generation arises from the effects of inhomogeneous Alfven speed and curvilinear field line. Around the magnetic equator, if the Alfven speed is inversely proportional to a power of the geocentric distance, these effects have magnitudes of the same order and their signs are identical.Considered in the present study is a situation that the earthward propagating compressional wave is launched from a large scale oscillating current wedge centered at midnight and symmetric about the magnetic equator. Then, it is found that the field-aligned current excited around the equator by the compressional wave has opposite senses in direction in the northern and southern hemispheres, in the pre-and post-midnight sectors as well as just inside the plasmapause and in its surrounding regions. As a result of the excitation of shear Alfven wave, two types of oscillations appear on a field line: One is a forced oscillation and the other is an eigenoscillation. Although a modulation of the compressional wave may be caused locally (or microscopically) around the equator by the eigenoscillation of field line, the modulation can be globally (or macroscopically) neglected. So far as the propagation along the source longitude (source-earth line) around the equator is concerned, the coupling between compressional and shear Alfven waves can be almost neglected and so one-dimensional response of the inner magnetosphere around the equator plays a significant role in the compressional oscillation.

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“…In order to check the existing Pi 2 models, Yumoto et al (1994) analyzed the magnetic field data from stations along the 210…”

Section: Introductionmentioning

confidence: 99%

Spectral power of low-latitude Pi 2 pulsations at the 210° magnetic meridian stations and plasmaspheric cavity resonances

2014

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Pi 2 pulsations at low latitudes are examined with magnetic fields data at the 210• magnetic meridian (MM) stations in 1991. Due to high degree of coherence over most latitudes, 68 low-latitude Pi 2 events at the 210• MM stations are identified with reference to same waveforms on the magnetogram at Lunping (189.5• MM, L = 1.06). With spectral power analysis, the ratio of the first four harmonic frequencies of low-latitude Pi 2 pulsations is about 1 : (1.7 ± 0.1) : (2.3 ± 0.1) : (2.9 ± 0.1). By using a box model for the inner magnetosphere, the cold linearized MHD wave equations are studied with realistic Alfven speed profile for nonuniform ambient magnetic fields. With appropriate parameters to depict the magnetospheric environments during the aforementioned period, numerical results are acquired with the fourth order Runge-Kutta method. It is found that the ratio of the first four harmonic frequencies of plasmaspheric cavity resonances is about 1 : 1.7 : 2.4 : 3.1 that is consistent with data analysis. This suggests that low-latitude Pi 2 pulsations at the 210• MM stations may be plasmaspheric cavity resonances driven by fast compressional waves owing to the impulsive source at the magnetotail.

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Correlation of High- and Low-Law-Latitude Pi 2 Magnetic Pulsations Observed at 210.DEG. Magnetic Meridian Chain Stations.

Cited by 31 publications

References 32 publications

Simultaneous DMSP, all-sky camera, and IMAGE FUV observations of the brightening arc at a substorm pseudo-breakup

Simultaneous DMSP, all-sky camera, and IMAGE FUV observations of the brightening arc at a substorm pseudo-breakup

The Excitation of Shear Alfven Wave and the Associated Modulation of Compressional Wave in the Inner Magnetosphere.

Spectral power of low-latitude Pi 2 pulsations at the 210° magnetic meridian stations and plasmaspheric cavity resonances

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