Direct Evidence of Drift‐Compressional Wave Generation in the Earth's Magnetosphere Detected by Arase

Autor: K. Yamamoto, A. V. Rubtsov, D. V. Kostarev, P. N. Mager, D. Yu. Klimushkin, M. Nosé, A. Matsuoka, K. Asamura, Y. Miyoshi, S. Yokota, S. Kasahara, T. Hori, K. Keika, Y. Kasahara, A. Kumamoto, F. Tsuchiya, M. Shoji, S. Nakamura, I. Shinohara
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Geophysical Research Letters, Vol 51, Iss 8, Pp n/a-n/a (2024)
Druh dokumentu: article
ISSN: 1944-8007
0094-8276
DOI: 10.1029/2023GL107707
Popis: Abstract We present the first direct evidence of an in situ excitation of drift‐compressional waves driven by drift resonance with ring current protons in the magnetosphere. Compressional Pc4–5 waves with frequencies of 4–12 mHz were observed by the Arase satellite near the magnetic equator at L ∼ 6 in the evening sector on 19 November 2018. Estimated azimuthal wave numbers (m) ranged from −100 to −130. The observed frequency was consistent with that calculated using the drift‐compressional mode theory, whereas the plasma anisotropy was too small to excite the drift‐mirror mode. We discovered that the energy source of the wave was a drift resonance instability, which was generated by the negative radial gradient in a proton phase space density at 20–25 keV. This proton distribution is attributed to a temporal variation of the electric field, which formed the observed multiple‐nose structures of ring current protons.
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