Relation between the variation of geomagnetospheric relativistic electron flux and storm/substorm

This paper studies the variations of the interplanetary field (IMF), solar wind, Kp index, D_st index, AE index and flux of relativistic electrons (E ≥ 1 MeV). The analysis shows that geomagnetic storms/substorms can occur when the component B_z of the IMF is southward and the velocity of the solar wind increases to above 500 km/s. The flux of the relativistic electrons decreases during the main phase of storms, and then increases during the recovery phase of storms. However, the flux of relativistic electrons can increase and exceed the prestorm level just during the recovery phase of storms including many prolonged substorm activities. Furthermore, the larger the flux of electrons with energy being less than 300 keV is, the larger the flux of relativistic electrons is, which shows the substorm-injection electrons with energy being less than 300 keV may be an important source of relativistic electrons.