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Three-dimensional ring current decay modelThis work is an extension of a previous ring current decay model. In the previous work, a two-dimensional kinetic model was constructed to study the temporal variations of the equatorially mirroring ring current ions, considering charge exchange and Coulomb drag losses along drift paths in a magnetic dipole field. In this work, particles with arbitrary pitch angle are considered. By bounce averaging the kinetic equation of the phase space density, information along magnetic field lines can be inferred from the equator. The three-dimensional model is used to simulate the recovery phase of a model great magnetic storm, similar to that which occurred in early February 1986. The initial distribution of ring current ions (at the minimum Dst) is extrapolated to all local times from AMPTE/CCE spacecraft observations on the dawnside and duskside of the inner magnetosphere spanning the L value range L = 2.25 to 6.75. Observations by AMPTE/CCE of ring current distributions over subsequent orbits during the storm recovery phase are compared to model outputs. In general, the calculated ion fluxes are consistent with observations, except for H(+) fluxes at tens of keV, which are always overestimated. A newly invented visualization idea, designated as a chromogram, is used to display the spatial and energy dependence of the ring current ion differential flux. Important features of storm time ring current, such as day-night asymmetry during injection and drift hole on the dayside at low energies (less than 10 keV), are manifested in the chromogram representation. The pitch angle distribution is well fit by the function, J(sub o)(1 + Ay(sup n)), where y is sine of the equatorial pitch angle. The evolution of the index n is a combined effect of charge exchange loss and particle drift. At low energies (less than 30 keV), both drift dispersion and charge exchange are important in determining n.
Document ID
19960014063
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Fok, Mei-Ching (NASA Marshall Space Flight Center Huntsville, AL United States)
Moore, Thomas E. (NASA Marshall Space Flight Center Huntsville, AL United States)
Kozyra, Janet U. (Michigan Univ. Ann Arbor, MI United States)
Ho, George C. (Maryland Univ. College Park, MD United States)
Hamilton, Douglas C. (Maryland Univ. College Park, MD United States)
Date Acquired
September 6, 2013
Publication Date
June 1, 1995
Subject Category
Meteorology And Climatology
Report/Patent Number
NASA-CR-199996
NAS 1.26:199996
Accession Number
96N19522
Distribution Limits
Public
Copyright
Public Use Permitted.

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