Trapped and Precipitating Protons in the Inner Magnetosphere as Seen by IMAGE

Perez, J. D., X.-X Zhang, P. C:son Brandt, D. G. Mitchell, J.-M. Jahn, 
C. J. Pollock, and S. B. Mende


Images from the IMAGE satellite of precipitating protons (SU12/FUV) and
trapped protons at 8.5 (MENA) and 33 keV (HENA) are compared during three
periods:  (1) Aug. 12, 2000 from 10:00 UT to 11:45 UT just after the peak of
a strong geomagnetic storm, (2) June 2, 2001 from 1:00 to 3:45 UT during the
main phase and initial recovery of a weak storm, and (3) June 18, 2001 from
14:00 to 16:45 UT late in the recovery phase of another weak storm.  Some of
the features of the precipitating and trapped protons observed in these time
intervals have been previously reported for other events, especially the
fact that the strength of the precipitating protons and trapped protons do
not always correlate.  The primary new features are that (1) the fluxes of
the precipitating protons and both the 8.5 keV and 33 keV trapped protons
peak at similar magnetic latitudes, and that (2) the peak in the 8.5 keV
trapped protons is usually at the same MLT as the peak in the precipitating
protons while the peak in the 33 keV trapped protons is usually in a
different MLT region than the peak of the precipitating protons.   Some
possible mechanisms to explain these observations are presented, but
understanding this behavior should provide stringent tests for models of the
EarthÕs inner magnetosphere. 

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Journal of Geophysical Research, in press