EMIC waves converted from equatorial noise due to M/Q=2 ions in the plasmasphere: Observations from Van Allen Probes and Arase

TitleEMIC waves converted from equatorial noise due to M/Q=2 ions in the plasmasphere: Observations from Van Allen Probes and Arase
Publication TypeJournal Article
Year of Publication2019
AuthorsMiyoshi, Y, Matsuda, S, Kurita, S, Nomura, K, Keika, K, Shoji, M, Kitamura, N, Kasahara, Y, Matsuoka, A, Shinohara, I, Shiokawa, K, Machida, S, Santolik, O, Boardsen, SA, Horne, RB, Wygant, JF
JournalGeophysical Research Letters
Date Published04/2019
ISSN0094-8276
KeywordsArase; EMIC; M/Q=2 ions; Magnetsonic waves; plasmasphere; Van Allen Probes
AbstractEquatorial noise (EN) emissions are observed inside and outside the plasmapause. EN emissions are referred to as magnetosonic mode waves. Using data from Van Allen Probes and Arase, we found conversion from EN emissions to electromagnetic ion cyclotron (EMIC) waves in the plasmasphere and in the topside ionosphere. A low frequency part of EN emissions becomes EMIC waves through branch splitting of EN emissions, and the mode conversion from EN to EMIC waves occurs around the frequency of M/Q=2 (deuteron and/or alpha particles) cyclotron frequency. These processes result in plasmaspheric EMIC waves. We investigated the ion composition ratio by characteristic frequencies of EN emissions and EMIC waves and obtained ion composition ratios. We found that the maximum composition ratio of M/Q=2 ions is ~10% below 3000 km. The quantitative estimation of the ion composition will contribute to improving the plasma model of the deep plasmasphere and the topside ionosphere
URLhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL083024
DOI10.1029/2019GL083024
Short TitleGeophys. Res. Lett.


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