Occurrence of severe geomagnetic storms and their association with solar-interplanetary features

Abstract. Severe geomagnetic storms are observed to be the largest 2 % of all large geomagnetic storms. Here great geomagnetic storms with Dst magnitude <-200 nT are considered. In this paper all severe geomagnetic storms have been selected which have occurred during year 1996 to 2005.We have found 16 severe geomagnetic storms during this period. These storms are significant not only because of the extremely high magnetic activity but also due to their great impact on the geomagnetosphere. The relationship of severe geomagnetic storms with different interplanetary parameters and their solar source origin are presented. We have found that 95 % severe geomagnetic storms are associated with halo coronal mass ejections