Characteristics of dawnside mid-latitude VLF emissions associated with substorms as deduced from the two-stationed direction finding measurement

Hayakawa, Masashi; Tanaka, Yoshihito; Sazhin, Sergei; Okada, T.; Kurita, Kento

doi:10.1016/0032-0633(86)90117-0

Cited by 30 publications

(29 citation statements)

References 37 publications

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“…In this case, however, the starting longitudes of the eastward drifting become 69.1 ° and 109.8° for the first and second peaks, respectively, which seems to be rather different from the statistical results (HAYAKAWA et al, 1986a). So, it may be implied that 5 keV electrons in the evening sector injected associated with the second H- HAYAKAWA et al (1986b) exhibited a regular frequency drift of the maximum energy of the midlatitude VLF hiss (L = 3.0) observed at dawn time, of which increasing rate was mostly below 1.5 kHz/ hr. They have explained that the property is related to the energy dependence of drifting velocities of the electrons encircling from the evening to the dawn sectors through the midnight in the equatorial magnetosphere.…”

Section: Observations Of Vlf Emissions and The Analysis Of Frequency contrasting

confidence: 68%

“…The VLF hiss exhibited a regular frequency drift; the frequency (fmax) of the maximum energy increased with local time. It is explained that the property is due to the dispersion of the drifting velocities of energetic electrons drifting from the midnight sector of their initial injection toward the generation region (dawn sector) (HAYAKAWA et al, 1986b). This paper presents low-latitude VLF hiss observed at dawn time at Moshiri (L = 1.6) and Kagoshima (L = 1.2) stations in Japan associated with the severe magnetic storm (Kp = 8) on October 19-21, 1989.…”

Section: Introductionmentioning

confidence: 91%

“…This formula means that higher energetic electrons encircle the Earth in shorter time. Assuming ae = n/4, as was done by HAYAKAWA et al (1986b), we can calculate the drift velocity (deg./hr.) of electron from the value of T(s) in second, of which the result is shown in Fig.…”

Section: Observations Of Vlf Emissions and The Analysis Of Frequency mentioning

confidence: 99%

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Low-Latitude VLF Hiss Associated with the Severe Magnetic Storm on October 19-21, 1989.

Nishino¹,

Tanaka²

1994

J. geomagn. geoelec

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Low-latitude VLF hiss was observed at dawn time at Moshiri (L = 1.6) and Kagoshima (L = 1.2), Japan during 20hOOm UT to 23h30m UT on October 20, associated with the severe magnetic storm (Kp = 8) during October 19-21,1989. The VLF hiss with a band-limited spectrum exhibited an increase of frequency (fmax) of the maximum energy with local time. Based on the quasi-linear model for hisstype mid-latitude VLF emissions developed by SAZHIN (1984) and using electron density data by EXOS-D satellite, it is estimated that injected electrons of about 5 keV associated with the maximum depression of the magnetic H-component around 13h30m UT on October 20 contribute to the generation of the VLF hiss at dawn time around L = 4.8 of the magnetospheric equatorial region. The plasmapause has been disrupted due to the strong magnetospheric disturbances when the VLF hiss was observed. The increase of fmax may be due to a combined effect of the energy dependences of different drift starting longitudes of the hot electrons injected in the evening sector and of the drift velocities of the electrons encircling the Earth, and a temporal variation of the cold electron density in the generation region at dawn sector. Furthermore it is implied that the VLF hiss has penetrated through the ionosphere at the higher latitude than that of Moshiri and then propagated toward the low-latitude stations in the Earth-ionosphere waveguide mode.

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Section: Observations Of Vlf Emissions and The Analysis Of Frequency contrasting

confidence: 68%

Section: Introductionmentioning

confidence: 91%

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Low-Latitude VLF Hiss Associated with the Severe Magnetic Storm on October 19-21, 1989.

Nishino¹,

Tanaka²

1994

J. geomagn. geoelec

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“…The typical source of these electrons and their anisotropies are the same as for protons, particle injection from the nightside plasma sheet during magnetic storms [Tsurutani et al, 1975;Delport et al, 2012], or substorms [Thorne et al, 1974[Thorne et al, , 1977Smith, 1974, 1977;Hayakawa et al, 1986;Koons and Roeder, 1990;Meredith et al, 2001Meredith et al, , 2012Li et al, 2013]. However, electrons drift from midnight through dawn, in the opposite sense as the protons.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic cyclotron waves in the dayside subsolar outer magnetosphere generated by enhanced solar wind pressure: EMIC wave coherency

et al. 2015

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Electromagnetic ion (proton) cyclotron (EMIC) waves and whistler mode chorus are simultaneously detected in the Earth's dayside subsolar outer magnetosphere. The observations were made near the magnetic equator 3.1°–1.5° magnetic latitude at 1300 magnetic local time from L = 9.9 to 7.0. It is hypothesized that the solar wind external pressure caused preexisting energetic 10–100 keV protons and electrons to be energized in the T⊥ component by betatron acceleration and the resultant temperature anisotropy (T⊥>T∥) formed led to the simultaneous generation of both EMIC (ion) and chorus (electron) waves. The EMIC waves had maximum wave amplitudes of ∼6 nT in a ∼60 nT ambient field B0. The observed EMIC wave amplitudes were about ∼10 times higher than the usually observed chorus amplitudes (∼0.1–0.5 nT). The EMIC waves are found to be coherent to quasi‐coherent in nature. Calculations of relativistic ∼1–2 MeV electron pitch angle transport are made using the measured wave amplitudes and wave packet lengths. Wave coherency was assumed. Calculations show that in a ∼25–50 ms interaction with an EMIC wave packet, relativistic electron can be transported ∼27° in pitch. Assuming dipole magnetic field lines for a L = 9 case, the cyclotron resonant interaction is terminated ∼±20° away from the magnetic equator due to lack of resonance at higher latitudes. It is concluded that relativistic electron anomalous cyclotron resonant interactions with coherent EMIC waves near the equatorial plane is an excellent loss mechanism for these particles. It is also shown that E > 1 MeV electrons cyclotron resonating with coherent chorus is an unlikely mechanism for relativistic microbursts. Temporal structures of ∼30 keV precipitating protons will be ∼2–3 s which will be measurable at the top of the ionosphere.

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“…The maximum of their occurrence corresponded to the middle latitudes (55-65 • ) which are connected with the plasmapause projection (Hayakawa et al, 1975a(Hayakawa et al, , b, 1977(Hayakawa et al, , 1986(Hayakawa et al, , 1988Dronov et al, 1985;Kleimenova, 1985).…”

Section: Plasmaspheric Hiss and Mid-latitude Hissmentioning

confidence: 99%

First results of low frequency electromagnetic wave detector of TC-2/Double Star program

et al. 2005

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Abstract. LFEW is a low frequency electromagnetic wave detector mounted on TC-2, which can measure the magnetic fluctuation of low frequency electromagnetic waves. The frequency range is 8 Hz to 10 kHz. LFEW comprises a boommounted, three-axis search coil magnetometer, a preamplifier and an electronics box that houses a Digital Spectrum Analyzer. LFEW was calibrated at Chambon-la-Forêt in France. The ground calibration results show that the performance of LFEW is similar to that of STAFF on TC-1. The first results of LFEW show that it works normally on board, and that the AC magnetic interference of the satellite platform is very small. In the plasmasphere, LFEW observed the ion cyclotron waves. During the geomagnetic storm on 8 November 2004, LFEW observed a wave burst associated with the oxygen ion cyclotron waves. This observation shows that during geomagnetic storms, the oxygen ions are very active in the inner magnetosphere. Outside the plasmasphere,

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Characteristics of dawnside mid-latitude VLF emissions associated with substorms as deduced from the two-stationed direction finding measurement

Cited by 30 publications

References 37 publications

Low-Latitude VLF Hiss Associated with the Severe Magnetic Storm on October 19-21, 1989.

Low-Latitude VLF Hiss Associated with the Severe Magnetic Storm on October 19-21, 1989.

Electromagnetic cyclotron waves in the dayside subsolar outer magnetosphere generated by enhanced solar wind pressure: EMIC wave coherency

First results of low frequency electromagnetic wave detector of TC-2/Double Star program

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