Solar Section        


January 31, 2021

Ramp Up of Solar Activity Cycle 25

By Theo Ramakers

I was asked if it was true that it seemed that Cycle 25 activity ramped up faster than previous rotations.  In order to try to shed some light into this, I am providing two graphs. It is noted here that each graph, while created by me, is based on data provided in the daily GEOalert notifications from NOAA’s Spaceweather Prediction Center (SWPC).  Each graph shows the value of the sum of all daily active region areas for a  Rotation  since January 1, 2008 (Blue lines, mostly in the middle, with their scale on the left).  Also shown is the number of spotless days.  (red lines at the side with the scale on the right). The difference between the two graphs is that one of them shows the number of consecutive spotless days at the end of this spotless period (Streak).
The second graph below shows the number of spotless days by ROTATION at the last day of the rotation  The number of these days reported by the size of the bars in this graph, don’t have to be consecutive, but the reported value is shown for an equal time period  for all (one rotation).  The Minimum for Cycle 23/24 (Beginning of Cycle 24) was in December of 2008.  The Minimum for Cycle 24/25 (Beginning of Cycle 25) was during December of 2019, giving a cycle duration of 11 years. It is clearly seen that the blue lines (indicating Solar Activity) don’t start showing in 2009, one year following the minimum , but this cannot be said for 2020, a year after the next minimum.  We surely see noticeable activity during the end of 2020. In addition, the Total Active Region Areas by Rotation show a higher value now than during the beginning of the previous solar minimum.  In fact the Total Active Region Area by Rotation did not exceed 5000 millionths until August 9, 2010, or 20 months after the previous minimum.  For the current Cycle, November 27, 2020 marks the first time where the 5000 millionths barrier was broken, and by well over 1000 millionths, which is only 11 months.  So to summarize the results so far, Cycle 25 seems to gain in activity much faster than Cycle 24 did.  We are eager to learn if this fast ramp up will continue.

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