The properties of solar active regions responsible for ground level enhancements during solar cycles 22 and 23

Abstract

This is a study designed to analyze the relationship between ground level enhancements (GLEs) and their associated solar active regions during solar cycles 22 and 23. Results show that 90.3% of the GLE events that are investigated are accompanied by X-class flares, and that 77.4% of the GLE events originate from super active regions. It is found that the intensity of a GLE event is strongly associated with the specific position of an active region where the GLE event occurs. As a consequence, the GLE events having a peak increase rate exceeding 50% occur in a longitudinal range from W20° to W100°. Moreover, the largest GLE events occur in a heliographic longitude at roughly W60°. Additionally, an analysis is made to understand the distributional pattern of the Carrington longitude of the active regions that have generated the GLE events. © 2013 National Astronomical Observatories of Chinese Academy of Sciences and IOP Publishing Ltd.