Outer zone energetic electron environment update

Abstract

Electron data (0.1 to 1.7 MeV) from the Medium Electrons A spectrometer on CRRES were used to train neural networks to predict daily averages of energetic fluxes at 5 energies and 6 L-values using the daily sum of the Kp magnetic field index. The trained networks were then used to process the entire Kp index from 1932 to 1996 (six complete solar cycles), providing daily estimates of the electron fluxes for the entire period. Superposed-epoch analysis of the six cycles shows the fluxes are minimum about six months after the solar sunspot minimum and maximize about three years after sunspot maximum. The variation over the solar cycle is about a factor of 2.3. Specific outputs from the study include long-term averages of fluxes, peak flux vs. energy and L, and flux vs. frequency-of-occurrence tables. The outputs were then used to generate a new model, ESA-SEE1, as an update to AE8. This study indicates that AE8 has excessive fluxes above 1 MeV beyond L=5.5, with the discrepancy being an order of magnitude at geosynchronous orbit. The high energy electrons peak in L about 0.5 L lower than indicated by AE8.