Since the mid 1970’s the statistics of flares has been intensively examined because of the clues that they might provide on both flare origins and flare prediction. A scientific debate has continued for more than 40 years in spite of the fact that most papers relay entirely or in part on the X-ray flare data generated by the GOES satellites. Here we report on clustering of flares during cycle 23, which spanned 1997 to 2008. Using a data set containing all flares from C5.0 through X in the maximum of cycle 23, 2000 to 2003, we find that 18.6% of the flares occurred in clusters that lasted more than a solar disk passage, 13 days (G13_Clusters). One lasted more than 3 disk passages, 42.6 days. The mean rate of flaring in G13_Clusters was 4.46 flares/day, while outside them the flare rate was 1.16 flares/day. G13_Clusters only occurred in solar maximum. We conclude that: 1) G13_Clusters are created from more than a single active region; 2) there is a global component because of the much higher sustained rate of flaring in the G13_Cluster periods; 3) if subsequence cycles are similar to cycle 23 it maybe possible to predict long periods of enhanced flare rates. The details vary, but the similar clustering occurs for GOES data sets with lower thresholds above C1.
Published on August 7, 2014
Speaker:Alan Title (Lockheed Martin Solar & Astrophysics Lab)