Relationships between quasi-periodic VLF emission and geomagnetic pulsation

Sato, Natsuo; Hayashi, K.; Kokubun, S.; Oguti, Takasi; Fukunishi, H.

doi:10.1016/0021-9169(74)90229-3

Cited by 84 publications

(78 citation statements)

References 13 publications

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“…However, their periods were different from the repetition periods of the QP emissions, and we were unable to determine any clear correspondence between these pulsations and QP emissions. Thus, these were considered to be type 2 QP emissions as categorized by Sato et al [1974]. Similar QP emissions were frequently observed during and after the campaign period at Athabasca, indicating that they are common features at that latitude.…”

Section: Qp Emissionsmentioning

confidence: 88%

“…Omura et al [2009] have simulated the nonlinear generation of rising-tone chorus waves in the equatorial plane of the magnetosphere. QP emissions have been further categorized into emissions associated with geomagnetic pulsations (type 1) or not thus associated with them (type 2) [e.g., Sato et al, 1974;Sazhin and Hayakawa, 1994;Engebretson et al, 2004]. Pasmanik et al [2004] reproduced the amplitude/frequency modulation of type 2 QP emissions without geomagnetic pulsations by using a self-consistent set of equations from quasilinear plasma theory of energetic electrons and whistler wave spectral energy density.…”

Section: 1002/2014ja020161mentioning

confidence: 99%

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Ground‐based ELF/VLF chorus observations at subauroral latitudes—VLF‐CHAIN Campaign

et al. 2014

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We report observations of very low frequency (VLF) and extremely low frequency (ELF) chorus waves taken during the ELF/VLF Campaign observation with High-resolution Aurora Imaging Network (VLF-CHAIN) of 17-25 February 2012 at subauroral latitudes at Athabasca (L = 4.3), Canada. ELF/VLF waves were measured continuously with a sampling rate of 100 kHz to monitor daily variations in ELF/VLF emissions and derive their detailed structures. We found quasiperiodic (QP) emissions whose repetition period changes rapidly within a period of 1 h without corresponding magnetic pulsations. QP emissions showed positive correlation between amplitude and frequency sweep rate, similarly to rising-tone elements. We found an event of nearly simultaneous enhancements of QP emissions and Pc1/electromagnetic ion cyclotron wave intensities, suggesting that the temperature anisotropy of electrons and ions developed simultaneously at the equatorial plane of the magnetosphere. We also found QP emissions whose intensity suddenly increased in association with storm sudden commencement without changing their frequency. Falling-tone ELF/VLF emissions were observed with their rate of frequency change varying from 0.7 to 0.05 kHz/s over 10 min. Bursty-patch emissions in the lower and upper frequency bands are often observed during magnetically disturbed periods. Clear systematic correlation between these various ELF/VLF emissions and cosmic noise absorption was not obtained throughout the campaign period. These observations indicate several previously unknown features of ELF/VLF emissions in subauroral latitudes and demonstrate the importance of continuous measurements for monitoring temporal variations in these emissions.

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Section: Qp Emissionsmentioning

confidence: 88%

Section: 1002/2014ja020161mentioning

confidence: 99%

Ground‐based ELF/VLF chorus observations at subauroral latitudes—VLF‐CHAIN Campaign

et al. 2014

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“…Quasi-periodic (QP) whistler emissions are the wide band emissions that are observed inside or near the plasmapause (see, for example, Helliwell (1965); Sato et al (1974); Hayakawa and Sazhin (1992); Sazhin and Hayakawa (1994)). They are characterized by a periodic modulation of wave intensity with typical periods from several seconds up to a few minutes.…”

Section: Introductionmentioning

confidence: 99%

“…One of the possible mechanisms of such periodic modulation is connected to geomagnetic pulsations of a corresponding period (Sato et al, 1974). But experimental data show that generation of QP emissions may occur in the absence of such disturbances (Oguti et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

Modeling whistler wave generation regimes in magnetospheric cyclotron maser

et al. 2004

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Abstract. Numerical analysis of the model for cyclotron instability in the Earth's magnetosphere is performed. This model, based on the self-consistent set of equations of quasilinear plasma theory, describes different regimes of wave generation and related energetic particle precipitation. As the source of free energy the injection of energetic electrons with transverse anisotropic distribution function to the interaction region is considered. A parametric study of the model is performed. The main attention is paid to the analysis of generation regimes for different characteristics of energetic electron source, such as the shape of pitch angle distributions and its intensity. Two mechanisms of removal of energetic electrons from a generation region are considered, one is due to the particle precipitation through the loss cone and another one is related to the magnetic drift of energetic particles.It was confirmed that two main regimes occur in this system in the presence of a constant particle source, in the case of precipitation losses. At small source intensity relaxation oscillations were found, whose parameters are in good agreement with simplified analytical theory developed earlier. At a larger source intensity, transition to a periodic generation occurs. In the case of drift losses the regime of self-sustained periodic generation regime is realized for source intensity higher than some threshold. The dependencies of repetition period and dynamic spectrum shape on the source parameters were studied in detail. In addition to simple periodic regimes, those with more complex spectral forms were found. In particular, alteration of spikes with different spectral shape can take place. It was also shown that quasi-stationary generation at the low-frequency band can coexist with periodic modulation at higher frequencies.On the basis of the results obtained, the model for explanation of quasi-periodic whistler wave emissions is verified.

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“…classified into type I and type II by Sato et al [1974] on the basis of whether or not they were well correlated with coincident geomagnetic pulsations. Other emissions types have been reported which show a degree of quasiperiodicity of somewhat shorter period, such as "hisslers" [Ungstrup and Carpenter, 1974] and "pulsing hiss" [Ward et al, 1982].…”

mentioning

confidence: 99%