LONG-TERM OBSERVATIONS OF KEV ION AND ELECTRON VARIABILITY IN THE OUTER RADIATION BELT FROM CRRES

The distribution of energetic electrons and ions with L-value (L less than or equal to 8) as measured by the Electron-Proton Angle Spectrometer onboard CRRES over the whole mission lifetime (July 1990 to October 1991) is presented. The outer radiation belt is shown to be highly dynamic, both in position and in strength. Substantial enhancements of electron and ion flux on short timescales are seen throughout most of the magnetosphere sampled by CRRES, and are strongly related to the Kp index and the ring current as measured by D-ST. These enhancements decay over less than 30 days. There is evidence of a magnetospheric electron and ion acceleration mechanism of considerable strength and efficiency. Very intense periods of activity (such as the March, 1991 storm) can lead to the creation of an additional, high-energy belt in the slot region, which persists over a period of many months.