There were no visible Sunspots on 11 March 2017. There was but one Sunspot cluster showing on 12 March. This will become more common as Solar Cycle continues on its way to its demise and the beginning of Cycle 25. From Wiki, we get the record of The “Spotless days at the end of the cycle”. These numbers have been recorded since Cycle 9 that ended in March 1855. The recent “grand maximum” beginning with Cycle 18 thru Cycle 22 provides us with these numbers:
|Cycle||Start/Finish||Max sunspots||Sunspotless days-end of cycle|
|24||Jan08/ ?||81.9 (Apr14)||?|
Cycle 24 has been much less active than its recent predecessors. It was ushered in following 817 spotless days. This appears to be significant but we probably need to see how this plays out at the end of Cycle 24 and its effect on Cycle 25.
The current, seemingly, most used way to predict the size of Cycle 25 is examining the Solar Polar Field Strength of Cycle 24. As noted in previous postings the technique is to examine the average field strength after the Maximum occurs. Typically, it levels out. The average field strength is computed by adding North and South field strengths and dividing by 2. Below is a plot of the field strength for Cycles 21,22,23 and 24. Looking at the left
plot, so far the Cycle 24 average is about 50. The high point for Cycle 23 looks to have been about 70. This suggests that Cycle25 will be smaller than 24. But Cycle 24 average field strength of nominally about 50, could become larger over the next year. So again, we will have to wait and see.
(Unfortunately, the expanded left chart is unavailable.An expanded left chart was put in this posting but it was too large to show the period of the Cycle 23 and 24.)
Below is the February 2017 Cycle 24 chart comparing it to Cycle 23.