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My guess is the Sun and its interaction with our planet is going to turn out to much more complex then some of us Apes really want it to be. The known cycles are: 27 day; 11 year; 22 year; 80 year; 180 year; and longer. We typically measure Watts/square meter and count sunspots, but that is going to turn out to be only a very small part of the overall picture. Besides sunspot cycle amplitude there is also sunspot cycle length, solar equatorial rotational rate, penumbral spot fractions and the sunspot cycle decay rate. Besides normal average irradiance there are also energetic flares that can increase UV radiation by 16 %. That UV is absorbed by Ozone in the stratosphere and the heat has been shown to propagate down and affect the circulation in the Troposphere. Solar radio flux has also been shown to vary quite dramatically. Solar winds and geomagnetic storm strengths have been shown to cause ionization warming in the polar auroral zones. Solar Wind output has been shown to affect the number of Galactic Cosmic Rays that reach Earth. In addition to all these factors, the sun can be very unpredictable. Just examine the incredibly intense Radio Flux and Huge Sunspot Areas that occurred from October 23 to November 3rd of 2003. That was during a falling sunspot cycle that was only at half amplitude. Additionally, disturbances that occur in the equatorial region of the sun may also affect our planet much greater due to the orbital plane. NASA itself readily admits that we are just getting started with respect to monitoring and fully understanding Solar Weather. So the factors I listed here are just what we will find in the introductory section of the Solar Weather textbook.

FYI - Concerning that October 23 to November 3rd of 2003 time frame. There were two very large flares that were sent our way. On October 28th 2003 an X17.2 was the 4th largest flare we have ever seen. Image courtesy of SolarCycle24.com.

Then on October 29th 2003 an X10 flare was the 20th largest flare we have ever seen. Image courtesy of SolarCycle24.com.

Then on November 4th 2003 the largest solar flare we have ever seen occurred and it was an incredible X28+. Lucky for us the Earth and Sun had moved enough by then that the super flare was not aimed at our planet.

SolarCycle24.com Movie

Also forgot to note the Coronal Mass Ejections (CME) that affect Earths magnetosphere. They are so powerful they can cause damage to satellites and electrical transmission lines. Trillions of watts of power are created and directed back to the Earth's upper atmosphere when these CME's hit our magnetopshere.

Thanks for your excellent post. I wasn’t satisfied with references to the 11 year solar cycle as though that said it all. I knew it had to be more complicated.

Looking at graphs of annual sunspots, I could make out a cycle but not a regular 11 year cycle.

Even with improved understanding, I suspect we will be left with a random, unexplained component to solar behavior.