Solar cycle variations in the inner zone proton belt configuration

Using a 2-D (longitude and latitude) cross-correlation between sets of SEUs from the TOMS satellite in the inner zone in 1992 and 1995, it is shown that the centroid of the energetic proton ensemble causing these SEUs moved to lower L (1.26 vs. 1.29 for the protons) during this period. This change in the energetic proton distribution at low altitude is due to the change in atmospheric scale height during the declining phase of the solar cycle. The AP8 model does not predict this change in the location in L of the peak in the inner zone protons.