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Title: “Trunk-like” heavy ion structures observed by the Van Allen Probes

Dynamic ion spectral features in the inner magnetosphere are the observational signatures of ion acceleration, transport, and loss in the global magnetosphere. Here, we report “trunk-like” ion structures observed by the Van Allen Probes on 2 November 2012. This new type of ion structure looks like an elephant's trunk on an energy-time spectrogram, with the energy of the peak flux decreasing Earthward. The trunks are present in He + and O + ions but not in H +. During the event, ion energies in the He+ trunk, located at L=3.6–2.6, magnetic local time (MLT)=9.1–10.5, and magnetic latitude (MLAT) =-2.4–0.09°, vary monotonically from 3.5 to 0.04 keV. Values at the two end points of the O + trunk are energy=4.5–0.7keV, L=3.6–2.5, MLT=9.1–10.7, and MLAT=-2.4–0.4°. Our results from backward ion drift path tracings indicate that the trunks are likely due to (1) a gap in the nightside ion source or (2) greatly enhanced impulsive electric fields associated with elevated geomagnetic activity. Different ion loss lifetimes cause the trunks to differ among ion species.
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [3] ;  [1] ;  [4] ;  [3] ;  [1] ;  [5]
  1. Univ. of New Hampshire, Durham, NH (United States). Space Science Center
  2. Rice Univ., Houston, TX (United States). Dept. of Physics and Astronomy
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). ISR Space Science and Applications
  4. National Aeronautics and Space Administration, Greenbelt, MD (United States). Geospace Physics Lab.
  5. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Geology and Geophysics
Publication Date:
Report Number(s):
Journal ID: ISSN 2169-9380
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Volume: 120; Journal Issue: 10; Journal ID: ISSN 2169-9380
American Geophysical Union
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
Country of Publication:
United States
58 GEOSCIENCES; ion structure; ion injection; inner magnetosphere; magnetic storm; magnetic cloud; van allen probes
OSTI Identifier: