Progress of Solar Cycle 24 at High Latitudes

摘要

The 'extended' solar cycle 24 began in 1999 near 70 degrees latitude, similarly to cycle 23 in 1989 and cycle 22 in 1979. The extended cycle is manifested by persistent Fe XIV coronal emission appearing near 70 degrees latitude and slowly migrating towards the equator, merging with the latitudes of sunspots and active regions (the 'butterfly diagram') after several years. Cycle 24 began its migration at a rate 40% slower than the previous two solar cycles, thus indicating the possibility of a peculiar cycle. However, the onset of the 'Rush to the Poles' of polar crown prominences and their associated coronal emission which has been a precursor to solar maximum in recent cycles (cf. Altrock 2003) has just been identified in the northern hemisphere. Peculiarly, this 'Rush' is leisurely, at only 50% of the rate in the previous two cycles. The properties of the current 'Rush to the Poles' yields an estimate of 2013 or 2014 for solar maximum.