The source of O+ in the storm time ring current. Issue 6 (23rd June 2016)

• Record Type: Journal Article
• Authors: Kistler, L. M.; Mouikis, C. G.; Spence, H. E.; Menz, A. M.; Skoug, R. M.; Funsten, H. O.; Larsen, B. A.; Mitchell, D. G.; Gkioulidou, M.; Wygant, J. R.; Lanzerotti, L. J.
• Is Part Of: Journal of geophysical research. Volume 121:Issue 6(2016:Jun.)
• Page Start: 5333
• Page End: 5349
• Publication Date: 2016-06-23
• Subjects: ring current -- oxygen -- plasma sources -- ionosphere -- plasma sheet -- geomagnetic storm; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2015JA022204
• Languages: English
• ISSNs: 2169-9380

Abstract

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. Key Points: Auroral outflow during the storm main phase mainly impacts <1 keV plasma sheet population The >1 keV (hot) more isotropic plasma sheet O + population increases prior to the main phase Inward transport of the hot O + dominates the ring current; this O + is likely from the cusp