O ⁺ ion conic and plasma sheet dynamics observed by Van Allen Probe satellites during the 1 June 2013 magnetic storm: Energetic Inner Magnetosphere O ⁺ Ions

Journal Article · Sat May 07 00:00:00 EDT 2016 · Journal of Geophysical Research. Space Physics

DOI:https://doi.org/10.1002/2015JA021795· OSTI ID:1402592

Burke, W. J. ^[1]; Erickson, P. J. ^[2]; Yang, J. ^[3]; Foster, J. ^[2]; Wygant, J. ^[4]; Reeves, G.  ^[5]; Kletzing, C. ^[6]

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1. Boston College, Chestnut Hill, MA (United States). Inst. for Scienctific Research
2. MIT Haystack Observatory, Westford, MA (United States)
3. Univ. of Massachusetts, Lowell, MA (United States). Center for Atmospheric Research
4. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Physics and Astronomy
5. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
6. Univ. of Iowa, Iowa City, IA (United States). Dept. of Physics and Astronomy

The Van Allen Probe satellites were near apogee in the late evening local time sector during the 1 June 2013 magnetic storm's main phase. About an hour after crossing the ring current's “nose structure” into the plasma sheet, the satellites encountered a quasiperiodic sequence of 0.08–3 keV O⁺ ions. Pitch angle distributions of this population consistently peaked nearly antiparallel to the local magnetic field. We then interpret this population as O⁺ conics originating in the northern ionosphere. The sequences began as fairly steady state conic fluxes with energies in the ~ 80 to 100 eV range. Over about a half hour buildup phase, O⁺ energies peaked near 1 keV. During subsequent release phases lasting ~ 20 min, O⁺ energies returned to low-energy starting points. We argue these observations reflect repeated formations and dissolutions of downward, magnetically aligned electric fields (ε||) layers trapping O⁺ conics between mirror points within heating layers below and electrostatic barriers above. Nearly identical variations were observed at the locations of both satellites during 9 of these 13 conic cycles. Phase differences between cycles were observed at both spacecraft during the remaining events. Most “buildup” to “release” phase transitions coincided with AL index minima. But, in situ magnetometer measurements indicate only weak dipolarizations of tail-like magnetic fields. The lack of field-aligned reflected O⁺ and tail-like magnetic fields suggest that both ionospheres may be active. However, Southern Hemisphere origin conics cannot be observed since they would be isotropized and accelerated during neutral sheet crossings.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE; National Aeronautics and Space Administration (NASA)
• Grant/Contract Number: AC52-06NA25396
• OSTI ID: 1402592
• Report Number(s): LA-UR-15-27238; TRN: US1702997
• Journal Information: Journal of Geophysical Research. Space Physics, Vol. 121, Issue 5; ISSN 2169-9380
• Publisher: American Geophysical Union
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
Heliospheric and Magnetospheric Physics