Since late last year, Solar Cycle 24 has picked up activity as it goes through a double peak maximum. I doubt that is an official term but it does describe what has been going on. It was generally though that the peak International Smoothed Sunspot number for Cycle 24 was going to be about 66. But the recent activity will result in a smoothed peak number of 81 or there about. (Click on charts for clarity.)
This chart of approximately the last 12 months, shows that F-10.7cm solar flux and Sunspot numbers are closely aligned, both being good proxies for solar activity.
The peak international (not smoothed) Sunspot number of 91.9 occurred in March 2014. A rare day of no Sunspots happened on Thursday 17th of July. The chart below shows July Sunspot numbers through the 24th:
SILSO’s predictions for Sunspot count over the next several months are shown below:
Looking at the following chart one can see that Cycle 24 is still much less active than its predecessors:
Note that Cycle 24’s ramp up to the maximum is less steep than 21 through 23. One can see that Cycles 21, 22 and 23 that the cycle length is related to how much time was taken to reach the maximum. If this holds true for Cycle 24, it should have a greater length.
There are many theories regarding how the Sun affects our climate. Some are too new to have enough time to prove if their predictions are supported or are going to be supported by actual data. Some of them make the length of the Solar Cycle important in predicting the global climate. Quoting from the David Archibald paper “Solar Cycles 24 and 25 and Predicted Climate Response” for Energy and Environment Volume 17 No. 1 2006 pages 29-35. Archibald sites several papers dealing with cycle length.
“Friis-Christensen and Lassen (1991), examining data over the period 1850 to 1990, found that length of the solar cycle has a very good match with temperature, and that this correlation is better than that of sunspot number and temperature. That paper concluded by stating, ’70-90 year oscillation in global mean temperature are correlated with corresponding oscillations in solar activity. Whereas the solar influence is obvious in the data from the last four centuries, signatures of human activity are not yet distinguishable in the observations’ “
A new paper in 2001 by Thejll and Lassen updated the preceding paper and concluded that the cycle length and temperature broke down after 1975 and that antropogenic warming was thought to be the reason. Apparently something did cause the change but in view of the lack of warming in the current century in spite of the continued increase in atmospheric CO2, the cause may not have accurately been determined in this Thejll and Lassen paper.
Previous postings on this blog that deal with the Sun’s link with climate can be examined by going to “categories” and then to Solar Cycle 25.
New postings on Sun’s predictions will appear soon.