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.
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.)
The 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.
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.
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 http://www.solen.info/solar/. 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, 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?
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’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):