Eruptive prominences and long-delay geomagnetic storms

Wright and McNamara (1983) found that long-delay geomagnetic storms are predominantly associated with filaments that disappear at heliographic longitudes greater than 50 deg. They noted no significant difference in this effect between the east and west hemisphere. The Wright and McNamara sample of filaments is presently divided into annular domains determined by the angular distance from the disk center and supplemented by the addition of eruptive prominences which are disappearing filaments of the limb. It is shown that long delay storms are associated with filaments that are well removed from the disk center. In addition, especially in the case of large filaments and prominences, the proportion of events that produce long delay storms are noted to have increased with angular distance from the disk center.