5. Conclusions
In this study, based on the high-resolution proton flux data from
RBSPICE onboard the Van Allen Probe B during 2013 – 2016, we have
performed a detailed statistical analysis of the global distribution of
reversed energy spectra of ring current protons. The major conclusions
are summarized as follows:
(1) The reversed proton energy spectra are preferentially observed
inside the plasmasphere, with the occurrence rates > 90%
at L ~ 2 - 4 during geomagnetically quiet periods. As
the geomagnetic activity intensifies, the preferential occurrence region
of the reversed proton energy spectra shrinks to lower L shells
(~2.5 - 3.5).
(2) The proton energies corresponding to the flux maxima and minima of
the reversed energy spectra decrease with the increase of L shell in the
region of L < 5. The flux minima of the reversed proton
spectra mainly occur at ~50 - 100 keV, while the flux
maxima are generally present at ~200 - 400 keV.
(3) Similar to the global distribution of the reversed spectrum
occurrence rate, the ratios between flux maxima and minima are strongly
L shell and geomagnetic activity dependent, showing that the ratios
during active times and at higher L shells are smaller than those during
quiet times and at lower L shells.