Equatorial Evolution of the Fast Magnetosonic Mode in the Source Region: Observation-Simulation Comparison of the Preferential Propagation Direction

TitleEquatorial Evolution of the Fast Magnetosonic Mode in the Source Region: Observation-Simulation Comparison of the Preferential Propagation Direction
Publication TypeJournal Article
Year of Publication2018
AuthorsMin, K, Boardsen, SA, Denton, RE, Liu, K
JournalJournal of Geophysical Research: Space Physics
Date Published11/2018
Keywords2D particle‐in‐cell simulation; Fast Magnetosonic Waves; Perpendicular propagation; Van Allen Probes
AbstractRecent analysis of an event observed by the Van Allen Probes in the source region outside the plasmapause has shown that fast magnetosonic waves (also referred to as equatorial noise) propagate preferentially in the azimuthal direction, implying that wave amplification should occur during azimuthal propagation. To demonstrate this, we carry out 2‐D particle‐in‐cell simulations of the fast magnetosonic mode at the dipole magnetic equator with the simulation box size, the magnetic field inhomogeneity, and the plasma parameters chosen from the same event recently analyzed. The self‐consistently evolving electric and magnetic field fluctuations are characterized by spectral peaks at harmonics of the local proton cyclotron frequency. The azimuthal component of the electric field fluctuations is larger than the radial component, indicating wave propagation mainly along the azimuthal direction. Because the simulation box is within the source region, this also implies wave amplification mainly during azimuthal propagation. The excellent agreement between the wave polarization properties of the present simulations and the recently reported observations is clear evidence that the main wave amplification occurs during azimuthal propagation in the source region.
URLhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026037
DOI10.1029/2018JA026037
Short TitleJ. Geophys. Res. Space Physics


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