Statistical Study of Selective Oxygen Increase in High-Energy Ring Current Ions During Magnetic Storms

K. Mitani, K. Seki, K. Keika, M. Gkioulidou, L. J. Lanzerotti, D. G. Mitchell, C. A. Kletzing, A. Yoshikawa, Y. Obana

研究成果: ジャーナルへの寄稿記事

抜粋

Ion transport from the plasma sheet to the ring current is the main cause of the development of the ring current. Energetic (>150 keV) ring current ions are known to be transported diffusively in several days. A recent study suggested that energetic oxygen ions are transported closer to the Earth than protons due to the diffusive transport caused by a combination of the drift and drift-bounce resonances with Pc 3–5 ultralow frequency waves during the 24 April 2013 magnetic storm. To understand the occurrence conditions of such selective oxygen increase (SOI), we investigate the phase space densities (PSDs) between protons and oxygen ions with the first adiabatic invariants (μ) of 0.1–2.0 keV/nT measured by the Radiation Belt Storm Probes Ion Composition Experiment instrument on the Van Allen Probes at L ~ 3–6 during 90 magnetic storms in 2013–2017. We identified the SOI events in which oxygen PSDs increase while proton PSDs do not increase during a period of ~9 hr (one orbital period). Among the 90 magnetic storms, 33% were accompanied by the SOI events. Global enhancements of Pc 4 and Pc 5 waves observed by ground magnetometers during the SOI events suggest that radial transport due to combination of the drift-bounce resonance with Pc 4 oscillations and the drift resonance with Pc 5 oscillations can be the cause of SOIs. The contribution of the SOI events to the magnetic storm intensity is roughly estimated to be ~9% on average.

元の言語英語
ページ(範囲)3193-3209
ページ数17
ジャーナルJournal of Geophysical Research: Space Physics
124
発行部数5
DOI
出版物ステータス出版済み - 5 2019

    フィンガープリント

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

これを引用

Mitani, K., Seki, K., Keika, K., Gkioulidou, M., Lanzerotti, L. J., Mitchell, D. G., ... Obana, Y. (2019). Statistical Study of Selective Oxygen Increase in High-Energy Ring Current Ions During Magnetic Storms. Journal of Geophysical Research: Space Physics, 124(5), 3193-3209. https://doi.org/10.1029/2018JA026168