«The Signal of the 11 - Year Sunspot Cycle in the Upper Troposphere - Lower Stratosphere.» (history.aip.org)
«While the earlier estimate of ± 20 % [Schulz, 2002] is consistent with a solar cycle (the 11 - year sunspot cycle varies in period by ± 14 %), a much higher precision would point more to an orbital cycle. (skepticalscience.com)
The results of three separate studies seem to show that even as the current sunspot cycle swells toward the solar maximum, the sun could be heading into a more - dormant period, with activity during the next 11 - year sunspot cycle greatly reduced or even eliminated. (dotearth.blogs.nytimes.com)