Saturday, July 15, 2023

A Little Cycle 25 Update

Back on my Wandering Around Monday, I noted that solar cycle 25 had just posted the highest sunspot number since cycle 23 back in 2002; the highest sunspot number in 21 years. I noted that Dr. Scott McIntosh, of the National Center for Atmospheric Research (NCAR) was set to do a presentation for an online group I follow and that I'd post an update as soon as it was available.  

I don't have a prepared presentation to lift graphics out of as of today, but I thought that I'd offer a little update based on watching the video of his presentation.  Since the one measure of solar activity that seems to be the most widely known is the 10.7cm solar flux (approx 2.80 GHz) I thought I'd present a screen capture of where we are in the cycle vs. his predictions. 

The dark green, not very smooth line is the predicted flux.  The wider, light green area is the included uncertainty bounds and the jagged red lines are short term measurements through the end of June '23.  To my eyes, the measured data is running a little below predicted but there's no attempt to plot some sort of average or get something closer to the dark green curve in appearance. 

Dr. McIntosh speculates that the peak of this cycle is going to be earlier than previously predicted, possibly before the end of '23 - and both his prediction and the consensus prediction for this peak have been pulled forward already (he comments that he's busy with predicting cycle 26).  Note that his dark curve shows a dual peak solar cycle with the two separated by about a year.  Most of the previous cycles show dual peaks, and the common explanation is that the behavior of the northern vs. the southern hemispheres of the sun aren't as symmetrical as cycles that have a single peak.

Interestingly, he presents another plot earlier in the video showing the two hemispheres are much more similar to each other than the previous two cycles.  

More information as it becomes available. 


  1. I'm a member of the Front Range 6 Meter Group, too, and saw the presentation. Pretty interesting. At least the prophets aren't running around screaming "It'll Be BIGGER Than Cycle 19!!!"......

    I finished getting all my ground rods driven in, and the clamps, plates, and bonding wire will continue this week, wx permitting. I'm itching to get my 6 Meter vertical OTA!

    1. The "bigger than Cycle 19!" crap is almost as annoying as everyone getting worked up over an X1 flare and anything stronger than an X2 is the next Carrington event. Dr. McIntosh was one of the "bigger than Cycle 19" crowd, but he had a reasonable basis for his prediction. It depended on the termination event happening at his predicted time. When it didn't happen, he revised his prediction down.

      As it is, we have a long way to go to be as strong as cycle 23, which wasn't particularly strong. See the plot of the cycles going back to the 1970s

      I've been listening to the CQ VHF contest and the propagation may be the worst I've ever heard for this contest. I've heard nothing consistently except the Florida peninsula, the EL95 to 99 and EL86 to 89.

    2. Not even anything on the digital modes? It's pretty dead out here, but sometimes we get some nice tropo to the East. Got these big, granite things blocking stuff to the West, though.
      Yeah, every time a new cycle starts the "experts" come out of the woodwork with all their obscure, arcane "theories" about why the next one will be BIG. It really does get pretty annoying.....

  2. Makes sense with the summer we've been having.