Multifrequency compressional magnetic field oscillations and their relation to multiharmonic toroidal mode standing Alfvén waves

TitleMultifrequency compressional magnetic field oscillations and their relation to multiharmonic toroidal mode standing Alfvén waves
Publication TypeJournal Article
Year of Publication2015
AuthorsTakahashi, K, Waters, C, Glassmeier, K-H, Kletzing, C, Kurth, W, Smith, CW
JournalJournal of Geophysical Research: Space Physics
Date Published11/2015
KeywordsCompressional oscillations; Field line resonance; Pc3-Pc4 band; plasmasphere; Van Allen Probes
AbstractThe power spectrum of the compressional component of magnetic fields observed by the Van Allen Probes spacecraft near the magnetospheric equator in the dayside plasmasphere sometimes exhibits regularly spaced multiple peaks at frequencies below 50 mHz. We show by detailed analysis of events observed on two separate days in early 2014 that the frequencies change smoothly with the radial distance of the spacecraft and appear at or very near the frequencies of the odd harmonics of mutiharmonic toroidal mode standing Alfvén waves seen in the azimuthal component of the magnetic field. Even though the compressional component had a low amplitude on one of the selected days, its spectral properties are highlighted by computing the ratio of the spectral powers of time series data obtained from two spatially separated Van Allen Probes spacecraft. The spectral similarity of the compressional and azimuthal components suggests that the compressional component contains field line resonance characteristics.
URLhttp://onlinelibrary.wiley.com/wol1/doi/10.1002/2015JA021780/abstract
DOI10.1002/2015JA021780
Short TitleJ. Geophys. Res. Space Physics


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