Title: Ion nose spectral structures observed by the Van Allen Probes

Abstract

Here, we present a statistical study of nose-like structures observed in energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet. Nose structures are spectral features named after the characteristic shapes of energy bands or gaps in the energy-time spectrograms of in situ measured ion fluxes. Using 22 months of observations from the Helium Oxygen Proton Electron (HOPE) instrument onboard Van Allen Probe A, we determine the number of noses observed, and the minimum L-shell reached and energy of each nose on each pass through the inner magnetosphere. We find that multiple noses occur more frequently in heavy ions than in H⁺, and are most often observed during quiet times. The heavy-ion noses penetrate to lower L shells than H⁺ noses and there is an energy-magnetic local time (MLT) dependence in the nose locations and energies that is similar for all species. The observations are interpreted using a steady-state model of ion drift in the inner magnetosphere. The model is able to explain the energy and MLT dependence of the different types of nose structures. Different ion charge exchange lifetimes are the main cause for the deeper penetration of heavy-ion noses. The species dependence and preferredmore » geomagnetic conditions of multiple-nose events indicate that they must be on long drift paths, leading to strong charge-exchange effects. The results provide important insight into the spatial distribution, species dependence, and geomagnetic conditions under which nose structures occur.« less

Authors:

Ferradas, C. P.  ^[1];

• Search DOE PAGES for author "Ferradas, C. P."
• Search DOE PAGES for ORCID "0000-0002-6931-1793"

Zhang, J. -C.  ^[1];

• Search DOE PAGES for author "Zhang, J. -C."
• Search DOE PAGES for ORCID "0000-0003-4405-0619"

Spence, H. E.  ^[1];

• Search DOE PAGES for author "Spence, H. E."
• Search DOE PAGES for ORCID "0000-0002-2526-2205"

Kistler, L. M.  ^[1];

• Search DOE PAGES for author "Kistler, L. M."
• Search DOE PAGES for ORCID "0000-0002-8240-5559"

Larsen, Brian Arthur  ^[2];

• Search DOE PAGES for author "Larsen, Brian Arthur"
• Search DOE PAGES for ORCID "0000-0003-4515-0208"

Reeves, Geoffrey D.  ^[2];

• Search DOE PAGES for author "Reeves, Geoffrey D."
• Search DOE PAGES for ORCID "0000-0002-7985-8098"

Skoug, Ruth M.  ^[2];

• Search DOE PAGES for author "Skoug, Ruth M."
• Search DOE PAGES for ORCID "0000-0003-1991-2643"

Funsten, Herbert O.  ^[2]

• Search DOE PAGES for author "Funsten, Herbert O."
• Search DOE PAGES for ORCID "0000-0002-6817-1039"

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+ Show Author Affiliations

1. Univ. of New Hampshire, Durham, NH (United States)
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Publication Date:

Tue Nov 22 00:00:00 EST 2016

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

National Aeronautics and Space Administration (NASA); USDOE

OSTI Identifier:

1335629

Report Number(s):

LA-UR-16-21732
Journal ID: ISSN 2169-9380

Grant/Contract Number:  

AC52-06NA25396

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Space Physics

Additional Journal Information:

Journal Name: Journal of Geophysical Research. Space Physics; Journal ID: ISSN 2169-9380

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Heliospheric and Magnetospheric Physics