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

Miyoshi, 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, S.A.; Horne, Richard B. ORCID: https://orcid.org/0000-0002-0412-6407; Wygant, J.F.. 2019 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, 46 (11). 5662-5669. https://doi.org/10.1029/2019GL083024

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Official URL: https://agupubs.onlinelibrary.wiley.com/doi/10.102...

Abstract/Summary

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 ~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.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1029/2019GL083024
ISSN:	0094-8276
Additional Keywords:	EMIC, magnetsonic waves, Arase, Van Allen Probes, plasmasphere, M/Q=2 ions
Date made live:	30 Apr 2019 11:39 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/523132

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1029/2019GL083024

ISSN:

0094-8276

Additional Keywords:

EMIC, magnetsonic waves, Arase, Van Allen Probes, plasmasphere, M/Q=2 ions

Date made live:

30 Apr 2019 11:39 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/523132