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

Abstract

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.

Localization of the Source of Quasiperiodic VLF Emissions in the Magnetosphere by Using Simultaneous Ground and Space Observations: A Case Study

“…Since many plasma and wave parameters are known from the data, it would be good to employ a theoretical model and simulate the observed event. The FCM model (Pasmanik et al, , ) seems to be suitable for such a study. We are leaving it for the future work.…”

Conjugate Observations of Quasiperiodic Emissions by the Van Allen Probes Spacecraft and Ground‐Based Station Kannuslehto

“…Considering the observed upper‐frequency limit of QP emissions, which appears to be related to one half of the equatorial electron cyclotron frequency and thus to ducted propagation (e.g., Němec et al, 2018), the assumption of ducted propagation appears to be supported. Moreover, the model was shown to successfully explain at least some of the QP emission features observed by satellites (Pasmanik et al, 2004; Pasmanik et al, 2019).…”

Progress in the Knowledge, Application and Influence of Extremely Low Frequency Signals

“…The relationship between SR perturbations and seismic activity is also currently being investigated [21] in order to carry out an increasingly effective prediction of the presence of seismic phenomena and alert the population of their effects. In the last year, the ELF natural phenomena community has also been investigating, developing numerical models of plasma spherical emissions [120], as well as plasma nonlinearity [121]. In the wave generation community, research continues the generation of these waves through increasingly complex mechanisms [122].…”