On the solar disk sources of very intense geomagnetic storms

In this work we present solar events responsible for producing very intense geomagnetic storms (Dst < -200 nT) occurring during both the ascending phase and maximum of solar cycle 23. Attempts are made to study the possible association between active regions and coronal holes observed on the solar disk and interplanetary geoeffective features, in particular coronal mass ejections (CMEs). We discuss the characteristic features of the coronal holes and flares or filament eruption as observed by SXT telescope on board Yohkoh and other ground-based observatories. The study of this association is important since it has geoeffective consequences and thus it could serve as a tool to predict geomagnetic activity.