Ring current ions and radiation belt electrons during geomagnetic storms driven by coronal mass ejections and corotating interaction regions

Abstract

Superposed epoch analyses of ring current (RC) ions and radiation belt (RB) electrons are conducted for geomagnetic storms with Dst < −100 nT during solar cycle 23. As a new approach, the storms are categorized into three groups in terms of the solar wind structures; storms with Dst > −130 nT associated with corotating interaction regions (CIRs), storms with Dst > −130 nT driven by coronal mass ejections (CMEs), and CME‐driven great storms with Dst < −130 nT. The flux enhancements of RB electrons and RC ions at L > 3.5 during the recovery phase largely depend on the solar wind structures; CIRs are significantly more effective for the evolution of the outer belt than are CMEs because of the existence of a series of particle injections driven by Alfvén waves within the fast coronal hole stream following the CIR. On the other hand, the flux enhancements of RB electrons and RC ions at L ≤ 3.0 largely depend on the strength of storms; only particular CMEs with a huge motional electric field and large dynamic pressure are effective in increasing the RB electrons and RC ions at L ≤ 3.0.