Category Archives: Solar Flux

Early look at Solar Cycle 24 July Activity

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.

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Solar Cycle24 Mid-November Update

Solar Cycle 24 at November mid-month still is showing relatively high activity. The Sunspots are up and the F10.7cm solar flux is as well.  The Solen Chart below was updated on 15 November.  (Click on Chart to enlarge.)

sunspotsmidnov13solarThe green line is not the official smoothed 6 month lagging number that is used to describe the Cycles.  But it currently is showing that the increase in solar activity in the month of October is still underway in November.  Even so, this activity is well below its recent predecessors.


Solar Cycle 24 October Update

The 30 day smoothed International Sunspot number for October 2013 was 78.9.  The Sun was more active as indicated by Sunspots and F10.7cm radio flux in October than any time since the middle of July this year.  The chart, by Solen, below shows this activity. (Click on chart to enlarge.)


The chart shows that the NOAA Sunspot number and the F10.7 cm flux are trending downward at month-end, indicating the likelihood that the 30-day smoothed Sunspot number will begin dropping.  A bit of prospective is that while the October solar activity was up, Cycle 24 is still much having much lower activity relative to the 3 preceding Solar Cycles.


Solar Cycle 24 October Sunspot Number Rising

It was beginning to look like the Sunspots were in freefall based on last month’s 30 day smoothed number of 36.9.  But the Sun continues to let us know that we don’t know a lot about it for certain.   It looks like the Cycle 24 Sunspot number may reach 70 for the month of October.  A jump in Sunspot activity began in second week of this month and has continued through the third week.  It will be interesting to see how high it will go.  This number is not the official smoothed 6 month lagging number* that will not move up a lot, unless this higher activity continues for several months.  See the Chart below that shows, in Green, the smoothed 30 day number at the last updating on 25 October 2013.   It is nearly 70 at this time. (Click on chart to enlarge.)


This chart is from  This is an excellent site for monitoring solar data.

*The smoothed number is calculated by doing a 13 month average from the numbers that lag 6 months behind the current month.


Penn And Livingston Cycle 25 Sunspot Forecast

Penn and Livingston, in their September 2010 IAU publication “Long-Term Evolution Of Sunspot Magnetic Fields” predicted that Solar Cycle 24 would peak at an International Sunspot number of 66 and Solar Cycle 25 at 7!!


Considering that NASA believes that the peak for Cycle 24 will be 67, their prediction looks pretty good.   So would you bet against their Cycle 25 prediction of 7?

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Solar Cycle 24 September 13 Update

The International Sunspot number for September dropped to 37 from 66 in August.    The F10.7cm solar flux moved downward as well from 115 in August to 103 in September.   Both are measures of Solar activity.  Again, Solar Cycle 24 is decidedly less active than recent Solar Cycles. (Click on the charts to improve clarity.  All charts are  by “Solar Terrestrial Activity Report”).


This chart, from Solen etc, is interesting.  The black line labled Ri is the International Sunspot number. The Rnorth indicates the number of Sunspots that were counted in the Sun’s northern hemisphere and Rsouth those formed in the southern hemisphere. Rnorth plus Rsouth equal Ri.  Rnorth peaked in late 2011 at about 97 Sunspots.  Rsouth peaked at about 50  in the middle of  last year.  The smoothed number is the official count.  The smoothed number is calculated by doing a 13 month average from the numbers that lag 6 months behind the current month.  The maximum smoothed number for Cycle 24 so far is 66.9 which occurred in early 2012.  Most of the solar cycle experts believe that will be the maximum for Cycle 24.

Below is the solar polar field strength chart updated for September showing the south and north poles have both crossed the  Sun’s equator.  It is suggested that you read the discussion regarding solar polar fields by clicking on this Forecasting Solar Cycle 25 Using The Solar Polar Field Strength”.


This chart puts Cycle 24 in perspective with Cycle 23.


The projected Sunspot number, shown in green, is also a 13 month average but it has no six month delay built into the calculation.


Solar Cycle 24— August 2013 Update

Solar Cycle 24’s Sunspot number bounced up a little as did the F10.7cm radio flux.   However, Cycle 24 is still on track to be the least active Cycle since the first part of the last century.  The Sun’s North pole appears to have firmly switched its polarity but the South Pole may be months away from switching its polarity.  A cycle’s “maximum” is usually called when both poles have done the swap.

The August Sunspot and the F10.7cm radio flux are shown below (Click on Charts to enhance view):

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Svensmark Theory—Cosmic Rays Contribute To Lower Global Temperatures

The previous posting closed with: Low Sunspot numbers and low F 10.7 indicate low solar activity.  How this activity translates to cooler weather is not clear.  The correlation between low activity and cooler weather has been know for several hundred year (or perhaps longer— recently read that the Chinese recorded Sunspot numbers many century’s ago and reported this correlation.)

One possible explanation is the Svensmark theory. This theory begins with high energy galactic cosmic rays (GCR) entering the Earth’s atmosphere where they collide with atmospheric molecules of oxygen. The collisions shatter the molecules and the resulting particles become nuclei for cloud droplets from which clouds are formed. Clouds reflect a significant amount of the Sun’s radiation back into space.  The weaker the Sun’s magnetic field (low solar activity),  the more GCR enter the atmosphere.  The more clouds, the more cooling.   This is opposed to the situation where the Sun’s activity is high, fewer GCR result in fewer clouds.

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Solar Cycle 24 Update-June 2013

Solar Cycle 24 activity was low in June.  Sunspots took a sizable drop from about 77 in May to 52 in June.  Solar flux dropped as well.  (Click on charts to enhance clarity.)



The experts believe that Cycle 24 will match Cycle 14.  NASA is predicting Cycle 24 Sunspot peak at 67 whereas Cycle 14’s peak was 64.   Cycle 14 began February, 1902 and ended August, 1913.  Temperatures during that time were much colder than the average since that time.  My March 8, 2013 posting has some interesting statistics to make comparisons of Cycle 24 and other Solar Cycles.  There is a plot of temperature anomalies from 1880 to 2010 that you can compare to Solar Cycle size. You can access that data by clicking here.



There was an uptick in Sunspot numbers and F10.7cm radio flux.   Sunspots monthly average went up to 72  versus  55 in March.   Cycle 24’s  pattern seems somewhat reminiscent of Cycle 23 during its time at or near maximum. (Click on charts to enlarge.)
cycles23_24APRIL13Chart curtsey of
Sunspots appear to be in sync with the predicted path shown as the green line in the chart.