Radial Transport of Higher-Energy Oxygen Ions Into the Deep Inner Magnetosphere Observed by Van Allen Probes
Abstract
The transport mechanism of the ring current ions differs among ion energies. Lower-energy (≲150 keV) ions are well known to be transported convectively. Higher-energy (≳150 keV) protons are reported to be transported diffusively, while there are few reports about transport of higher-energy oxygen ions. We report the radial transport of higher-energy oxygen ions into the deep inner magnetosphere during the late main phase of the magnetic storm on 23-25 April 2013 observed by the Van Allen Probes spacecraft. An enhancement of 1-100 mHz magnetic fluctuations is simultaneously observed. Observations of 3 and 30 mHz geomagnetic pulsations indicate the azimuthal mode number is ≤10. The fluctuations can resonate with the drift and bounce motions of the oxygen ions. The results suggest that the combination of the drift and drift-bounce resonances is responsible for the radial transport of higher-energy oxygen ions.
- Publication:
-
Geophysical Research Letters
- Pub Date:
- May 2018
- DOI:
- 10.1029/2018GL077500
- Bibcode:
- 2018GeoRL..45.4534M
- Keywords:
-
- Van Allen Probes;
- oxygen ion;
- ring current;
- magnetic storm