Guest essay by David Archibald
The latest image from the Solar Dynamics Observatory (SDO) shows our sun as a blank canvas. No sunspots. Solar cycle 24 activity continues to be lowest in nearly 200 years
According to NASA’s Spaceweather.com:
Sunspot number: 0
Updated 30 Jun 2016
Current Stretch: 7 days
2016 total: 11 days (6%)
2015 total: 0 days (0%)
2014 total: 1 day (<1%)
2013 total: 0 days (0%)
2012 total: 0 days (0%)
2011 total: 2 days (<1%)
2010 total: 51 days (14%)
2009 total: 260 days (71%)
The last time sunspots vanished for a whole week was in Dec. 2010–a time when the sun was bouncing back from a long Solar Minimum. In this case, the 7 week interregnum is a sign that a new Solar Minimum is coming.
The sunspot cycle is like a pendulum, swinging back and forth every 11-years or so between times of high and low sunspot number. The next low is expected in 2019-2020. Between now and then sunspots will become increasingly rare with stretches of days, then weeks, then months of “billiard-ball suns.”
The F10.7 flux has been in a disciplined downtrend for nigh on 18 months now. It is now only nine units above the immutable floor of activity of 64:
Figure 1: F10.7 flux 2014 – 2016
We have F10.7 data from 1948. Plotting up the whole solar cycles since then, Solar Cycle 24 has been following Solar Cycle 22:
Figure 2: F10.7 flux of Solar Cycle 24 and Solar Cycle 22
In Figure 2 above, Solar Cycle 24 (red line) has been following the activity of Solar Cycle 22 (black line) for the last two years. If it keeps following Solar Cycle 22’s activity, that will make it a weak, short cycle. Strong cycles such as Solar Cycle 22 are generally shorter than average and weak cycles are generally longer. The other solar cycles are shown as dotted lines.
The solar polar field strength divergence continues to build and is unprecedented in the record:
Figure 3: Solar Polar Magnetic Field Strength by Hemisphere
Finally, Figure 4 following shows that the peak of the F10.7 flux in Solar Cycle 24 was in February 2014. The Oulu neutron count duly turned up a year later (inverted in Figure 4) in March 2015.
Figure 4: F10.7 Flux and Inverted Oulu Neutron Count 1964 – 2016
What is interesting from Figure 4 is that there has been a consistent increase in the neutron count relative to F10.7 flux over Solar Cycle 24 relative to the relationship in the previous four cycles.
David Archibald is the author of Twilight of Abundance (Regnery).