Propagation properties of quasiperiodic VLF emissions observed by the DEMETER spacecraft

Hayosh, M.; Němec, F.; Santolı́k, O.; Parrot, M.

doi:10.1002/2015gl067373

Cited by 26 publications

(47 citation statements)

References 42 publications

(51 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ongoing research of QP waves with unique behavior on small latitudinal scales is important since they are naturally smoothed out in large statistics due to averaging [ Hayosh et al , ]. Figure presents spectrograms of power spectral density of electric field and θ kB angle for another two QP events showing the same characteristics as the event we have analyzed in Figure .…”

Section: Discussionmentioning

confidence: 99%

“…However, as the burst mode was mostly triggered at lower latitudes, data from latitudes higher than 50° were available only in about 140 cases of QP events. According to the results of Hayosh et al [], the observed direction of the Poynting vector is mostly downward, nearly perpendicular to the ground, and the dependence of θ kB on λ mag is fairly linear, decreasing from θ kB ≈70° at λ mag =50 ∘ to θ kB ≈30 ∘ at λ mag =60 ∘ .…”

Section: Datamentioning

confidence: 99%

“…Using the data from the DEMETER spacecraft, Hayosh et al [] recently analyzed wave properties of QP emissions, mainly the direction of the Poynting vector and the direction of the wave vector, as a function of the geomagnetic latitude. They show that values of the polar angle θ kB between the wave vector direction and the local magnetic field B 0 are always well below 90° at high latitudes in the Northern Hemisphere and well above 90° in the Southern Hemisphere, indicating propagation from the magnetosphere toward the Earth in both cases.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Observation of ionospherically reflected quasiperiodic emissions by the DEMETER spacecraft

Hanzelka

Santolı́k

Hajoš

et al. 2017

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

Quasiperiodic (QP) electromagnetic emissions are whistler mode waves at typical frequencies of a few kHz characterized by a periodic time modulation of their intensity. The DEMETER spacecraft observed events where the QP emissions exhibit a sudden change in the wave vector and Poynting vector directions. The change happens in a short interval of latitudes. We explain this behavior by ionospheric reflection and present a ray‐tracing simulation which matches resulting wave vector directions. We also attempt to locate the source region of these emissions and conclude that they are most probably generated at the inner boundary of the plasmapause which also acts as a guide during the propagation of the QP emissions.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Observation of ionospherically reflected quasiperiodic emissions by the DEMETER spacecraft

Hanzelka

Santolı́k

Hajoš

et al. 2017

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…Moreover, sometimes the event is observed by DEMETER at locations very close to Kannuslehto, but it is absent in the Kannuslehto data. This indicates that the waves may have difficulties penetrating from the DEMETER altitudes down to the ground, which seems to be consistent with their unducted propagation [ Němec et al , ; Titova et al , ; Hayosh et al , ].…”

Section: Discussionmentioning

confidence: 99%

Conjugate observations of a remarkable quasiperiodic event by the low‐altitude DEMETER spacecraft and ground‐based instruments

Němec

Bezděková

Manninen³

et al. 2016

JGR Space Physics

View full text Add to dashboard Cite

We present a detailed analysis of a long‐lasting quasiperiodic (QP) event observed simultaneously by the low‐altitude DEMETER spacecraft and on the ground by the instrumentation of the Sodankylä Geophysical Observatory, Finland. The event was observed on 26 February 2008. It lasted for several hours, and it was detected both in the Northern and Southern Hemispheres. The time intervals when the event was observed on board the satellite and/or on the ground provide us with an estimate of the event dimensions. When the event is detected simultaneously by the satellite and on the ground, the observed frequency‐time structure is generally the same. However, the ratio of detected intensities varies significantly as a function of the spacecraft latitude, indicating the wave guiding along the plasmapause. Moreover, there is a delay as large as about 13 s between the times when individual QP elements are detected by the spacecraft and on the ground. This appears to be related to the azimuthal separation of the instruments, and it is highly relevant to the identification of a possible source mechanism. We suggest that it is due to an azimuthally propagating ULF wave which periodically modulates the azimuthally extended source region. Finally, we find that at the times when the intensity of the QP event suddenly increases, there is a distinct increase of the amplitude of Alfvénic ULF pulsations measured on the ground at high latitudes. This might indicate that the source region is located at L shells larger than about 7.1.

show abstract

“…The main discrepancy between the modeling and observation results is for the upper frequency which is about 3 and 1.9 kHz, respectively (the frequency range in Figure a is limited to 2 kHz for consistency with Figure a in Hayosh et al, ). This could be related to the peculiarities of the wave propagation from the source to the point of their detection (Hayosh et al, ; Němec et al, ; Němec, Bezděková, et al, ; Němec, Hospodarsky, et al, ). In particular, the wave ducting becomes less efficient, and therefore, effective losses could increase as the frequency approaches one half of the electron gyrofrequency at the equator (which is equal to ≈6.9 kHz for L =4.0).…”

Section: Results Of Numerical Simulationsmentioning

confidence: 99%

Quasiperiodic ELF/VLF Emissions Detected Onboard the DEMETER Spacecraft: Theoretical Analysis and Comparison With Observations

et al. 2019

View full text Add to dashboard Cite

We present results of numerical simulation of quasiperiodic (QP) extra low frequency/very low frequency emissions performed by using a theoretical model of flow cyclotron maser based on a self‐consistent set of equations of the quasi‐linear plasma theory averaged over oscillations of waves and particles in a geomagnetic flux tube. Calculations were made for a wide range of plasma parameters (i.e., cold plasma density, L‐shell, and energetic electron flux) in order to obtain a statistical relationship between various properties of QP emissions, such as the repetition period, the frequency bandwidth, the frequency drift rate, and the characteristic wave spectral energy density. The theoretical results are compared with the results of a statistical study of QP emissions measured by the DEMETER spacecraft (Hayosh et al., 2014, https://doi.org/10.1002/2013JA019731). The simulation results are in a good agreement with the observation data in the case of reasonable choice of cold plasma density value and its dependence on the QP‐source location (L‐shell). In particular, an increase in the frequency bandwidth of QP very low frequency waves with increasing central frequency of QP emissions, a decrease in the frequency drift rate of QP elements with increasing repetition period, and a decrease in the characteristic wave spectral energy density with increasing repetition period are confirmed.

show abstract

Propagation properties of quasiperiodic VLF emissions observed by the DEMETER spacecraft

Cited by 26 publications

References 42 publications

Observation of ionospherically reflected quasiperiodic emissions by the DEMETER spacecraft

Observation of ionospherically reflected quasiperiodic emissions by the DEMETER spacecraft

Conjugate observations of a remarkable quasiperiodic event by the low‐altitude DEMETER spacecraft and ground‐based instruments

Quasiperiodic ELF/VLF Emissions Detected Onboard the DEMETER Spacecraft: Theoretical Analysis and Comparison With Observations

Contact Info

Product

Resources

About