EMIC Waves Converted From Equatorial Noise Due to M/Q=2 Ions in the Plasmasphere: Observations From Van Allen Probes and Arase

0511925 - ÚFA 2020 RIV US eng J - Journal Article
Miyoshi, Y. - Matsuda, S. - Kurita, S. - Nomura, K. - Keika, K. - Shoji, M. - Kitamura, N. - Kasahara, Y. - Matsuoka, A. - Shinohara, I. - Shiokawa, K. - Machida, S. - Santolík, Ondřej - Boardsen, S.A. - Horne, R. B. - Wygant, J.F.
EMIC Waves Converted From Equatorial Noise Due to M/Q=2 Ions in the Plasmasphere: Observations From Van Allen Probes and Arase.
Geophysical Research Letters. Roč. 46, č. 11 (2019), s. 5662-5669. ISSN 0094-8276. E-ISSN 1944-8007
Grant - others:AV ČR(CZ) AP1401; AV ČR(CZ) JSPS-17-14
Program: Akademická prémie - Praemium Academiae; Bilaterální spolupráce
Institutional support: RVO:68378289
Keywords : EMIC * magnetsonic waves * Arase * Van Allen Probes * plasmasphere * Q=2 ions * M
OECD category: Fluids and plasma physics (including surface physics)
Impact factor: 4.497, year: 2019
Method of publishing: Open access
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL083024

Equatorial 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 similar to 10% below 3,000 km. The quantitative estimation of the ion composition will contribute to improving the plasma model of the deep plasmasphere and the topside ionosphere.
Permanent Link: http://hdl.handle.net/11104/0302161