Relativistic electron microbursts during the GEM storms

Observations of relativistic (>1 MeV) electron microbursts by the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) satellite are frequently associated with geomagnetic storms. We examine the characteristics of these microbursts during 1997 and 1998, paying particular attention to the three storms selected by the Geospace Environment Modeling (GEM) community for special study: May 15, 1997, September 25, 1998, and October 19, 1998. The relativistic electron microbursts strongly correlate with both the Dst and Kp indices and generally increase in intensity and move to lower L shells during the recovery phases of geomagnetic storms. During the recovery phases of the September and October 1998 storms, the numbers of >1 MeV electrons lost from the radiation belts to the microburst precipitation are estimated to be 2.5 × 1025 and 3.3 × 1024, respectively. In both cases, the microburst loss is a significant fraction of the total radiation belt population.