First observation of rising-tone magnetosonic waves

TitleFirst observation of rising-tone magnetosonic waves
Publication TypeJournal Article
Year of Publication2014
AuthorsFu, HS, Cao, JB, Zhima, Z, Khotyaintsev, YV, Angelopoulos, V, ík, O, Omura, Y, Taubenschuss, U, Chen, L, Huang, SY
JournalGeophysical Research Letters
Pagination7419 - 7426
Date Published11/2014
Keywordsdiscrete; frequency sweep rate; magnetosonic wave; nonlinear wave-particle interaction; Plasmapause; rising tone
AbstractMagnetosonic (MS) waves are linearly polarized emissions confined near the magnetic equator with wave normal angle near 90° and frequency below the lower hybrid frequency. Such waves, also termed equatorial noise, were traditionally known to be “temporally continuous” in their time-frequency spectrogram. Here we show for the first time that MS waves actually have discrete wave elements with rising-tone features in their spectrogram. The frequency sweep rate of MS waves, ~1 Hz/s, is between that of chorus and electromagnetic ion cyclotron (EMIC) waves. For the two events we analyzed, MS waves occur outside the plasmapause and cannot penetrate into the plasmasphere; their power is smaller than that of chorus. We suggest that the rising-tone feature of MS waves is a consequence of nonlinear wave-particle interaction, as is the case with chorus and EMIC waves.
Short TitleGeophys. Res. Lett.

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