Statistical Characteristics of Substorms With Different Intensity

Geomagnetic substorm is one of the essential solar wind‐magnetosphere energy coupling processes. In this study, we present a statistical analysis of substorms with different intensities that occurred from 1982 to 2012. We investigated the substorm occurrence rate, the time evolution of solar wind and geomagnetic parameters, as well as the SME, SMU and, SML indices during these substorms by using OMNI and SuperMag networks data sets. We find that substorms more frequently occur during solar declining phases and in spring and autumn due to the Russel‐McPherron effect. The superposed SME index shows a double‐peak near midnight and dusk during intense substorms, standing for comparable eastward and westward electrojets. We suggest that there is an additional current wedge during intense substorms located near the dusk. During the substorm expansion phase, eastward and westward electrojets are expanding against their current direction. The results presented in this study provide a comprehensive view of substorm characteristics with different intensities and may facilitate the understanding of the development of auroral electrojets in the ionosphere, even the current system in the magnetosphere. Key Points Occurrence of modest substorms and intense substorms show different annual, monthly, and diurnal variations Superposed SME index during intense substorms shows a double‐peak distribution dominated by westward and eastward electrojets, respectively We found electrojets expansions during the substorm expansion phase and the recovery phase