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First observation of rising‐tone magnetosonic waves
Author(s) -
Fu H. S.,
Cao J. B.,
Zhima Z.,
Khotyaintsev Y. V.,
Angelopoulos V.,
Santolík O.,
Omura Y.,
Taubenschuss U.,
Chen L.,
Huang S. Y.
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl061867
Subject(s) - plasmasphere , physics , spectrogram , chorus , computational physics , geophysics , acoustics , van allen probes , magnetosphere , van allen radiation belt , magnetic field , art , literature , quantum mechanics , computer science , computer vision
Magnetosonic (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.