Multiple peaks in the spectrum of inner belt electrons

Abstract

We report on a systematic study of energetic electron spectra in the inner magnetosphere. The observations were made from the low‐altitude satellite S81‐1 during the period June–November 1982. The electron spectrometers covered the energy range 6 keV to 1 MeV. In most geographic areas the electron energy spectra are smooth, but in the region of the South Atlantic Anomaly the spectra often consist of a series of broad peaks. The number of peaks is typically three, but may be as many as eight, or in some cases there may be none. The peak‐to‐valley ratios are often an order of magnitude or more. Peaks in the spectra of electrons from 100 keV to above 1 MeV at higher altitudes have been reported earlier in conjunction with geomagnetic storms. At the 250‐km nominal altitude of the S81‐1 observations, peaks in the energetic electron spectra are observed on most days and at all levels of geomagnetic activity.