The source of O+ in the storm time ring current

L. M. Kistler, C. G. Mouikis, H. E. Spence, A. M. Menz, R. M. Skoug, H. O. Funsten, B. A. Larsen, D. G. Mitchell, M. Gkioulidou, J. R. Wygant, L. J. Lanzerotti

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

A stretched and compressed geomagnetic field occurred during the main phase of a geomagnetic storm on 1 June 2013. During the storm the Van Allen Probes spacecraft made measurements of the plasma sheet boundary layer and observed large fluxes of O+ ions streaming up the field line from the nightside auroral region. Prior to the storm main phase there was an increase in the hot (>1 keV) and more isotropic O+ ions in the plasma sheet. In the spacecraft inbound pass through the ring current region during the storm main phase, the H+ and O+ ions were significantly enhanced. We show that this enhanced inner magnetosphere ring current population is due to the inward adiabatic convection of the plasma sheet ion population. The energy range of the O+ ion plasma sheet that impacts the ring current most is found to be from ~5 to 60 keV. This is in the energy range of the hot population that increased prior to the start of the storm main phase, and the ion fluxes in this energy range only increase slightly during the extended outflow time interval. Thus, the auroral outflow does not have a significant impact on the ring current during the main phase. The auroral outflow is transported to the inner magnetosphere but does not reach high enough energies to affect the energy density. We conclude that the more energetic O+ that entered the plasma sheet prior to the main phase and that dominates the ring current is likely from the cusp.

Original languageEnglish (US)
Pages (from-to)5333-5349
Number of pages17
JournalJournal of Geophysical Research: Space Physics
Volume121
Issue number6
DOIs
StatePublished - Jun 1 2016

Bibliographical note

Funding Information:
Work at UNH was supported by NASA under grant NNX14AC03G and by RBSP-ECT funding provided by JHU/APL contract 967399 under NASA's prime contract NAS5-01072. The RBSPICE instrument is supported by JHU/APL subcontract 937836 to the New Jersey Institute of Technology under NASA prime contract NAS5-01072. HOPE data used in this paper were downloaded from http://www.rbsp-ect.lanl.gov/rbsp_ect.php. RBSPICE data were downloaded from http://rbspice.ftecs.com/. Solar wind plasma and IMF data and the Kp and Sym-H indices were obtained from http://omniweb.gsfc.nasa.gov.

Publisher Copyright:
©2016. American Geophysical Union. All Rights Reserved.

Keywords

  • geomagnetic storm
  • ionosphere
  • oxygen
  • plasma sheet
  • plasma sources
  • ring current

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