A new index of recurrence for long-lasting enhanced geomagnetic activity

A new index of recurrence for high, long-lasting enhancements of geomagnetic activity based on the daily geomagnetic character figures C 9 is proposed and calculated. The variations of the new index values and their periodicities are discussed. The main purpose of introducing this new index is the possibility of improved investigations of its correlation with the time and global distribution of various solar activity phenomena