Dynamic variations of the outer radiation belt during magnetic storms for 1.5-6.0 MeV electrons

The CME's structure of solar wind (interplanetary magnetic field) is different from CIR's. The two processes in which plasma and solar wind energy are injected into the Earth's inner magnetosphere are not the same. So, the variations of energetic electrons flux in the radiation belts are different between the storms associated with CMEs and CIRs. By using data from SAMPEX (Solar, Anomalous, and Magnetospheric Particle Explorer) satellite, we have investigated the dynamic variations of the outer radiation belt for 1.5-6.0 MeV electrons during 54 CME-driven storms and 26 CIR-driven recurrent storms. According to the superposed epoch analysis, for CME- and CIR-driven storms, when the Dst index reaches the minimum, the locations of the outer boundary move to L=4 and L=5.5, respectively. In the recovery phases, the locations of the outer boundary of the outer radiation belt are generally lower than and slightly higher than those before CME- and CIR-driven storms, respectively. We have found that the logarithmically decaying 1/e cut-off L-shell is a satisfying indicator of the outer boundary of the outer radiation belt. Furthermore, our study shows that the logarithmically decaying 1/e cut-off latitude is dependent on the Kp index in the main phases of CME- and CIR- driven storms, while in the recovery phases, there is no obvious correlation. In addition, it has been shown that the locations of the peak electron flux are controlled by the minimum Dst index in the main phases of CME-driven storms. The influences of multiple storms on the electron flux of outer radiation belt have also been investigated.