Predicting the L-position of the storm-injected relativistic electron belt Original Research Article

In the paper we confirm earlier work on the dependence of the L-position (Lmax) of the peak intensity of storm-injected relativistic electrons upon the magnetic storm amplitude |Dst|max. Early results for |Dst|max=30–140 nT were reported by Williams et al. (1968). Later studies gave the following formula: |Dst|max= 2.75·104/Lmax4 for |Dst| up to 400 nT (Tverskaya, 1986). This sort of relationship also can be applied to the lowest position of the westward electrojet center during the storm, and the boundaries of both the trapped radiation zone and discrete auroral forms. Data from high-altitude (Polar and 1997-068) satellites, and a low-altitude satellite (SAMPEX) were analyzed and compared to the predictions of the above formula. The congruence between formula and observations is excellent: the discrepancy is not larger than 0.2 Re. There are several reasons why the discrepancies might be expected including: fast radial transport due to sudden impulses; the overlapping in time of multiple storms; and the additional injections onto L>Lmax in the storm recovery phase. There could be difficulty relating high and low altitude measurements due to problems with magnetic field models, but we believe this is not a major factor in our analysis.