Solar Science

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K7RA on solar cycle “pessimists” and “optimists”

with 4 comments

An interesting overview on the two competing theories within NASA on Solar Cycle 24 from amateur solar watcher Tad Cook, also known under his radio ham designation K7RA:

A new forecast is out regarding progress between Solar Cycles 23 and 24. You may recall that the committee of scientists who make a group forecast of future sunspot activity for the NOAA Space Weather Prediction Center were unable to reach a consensus last year, the group evenly split between those who think the next solar cycle will be weak and those that see a stronger solar cycle.

I will refer to the weak cycle predictors as pessimists and strong cycle forecasters as optimists. While these characterizations may not be appropriate for scientists who presumably have no preference either way, as far as Amateur Radio operators are concerned, the high cycle prediction is no doubt the optimistic choice.

The previous prediction appeared in the January 2, 2008, issue 1687 of the Preliminary Report and Forecast. Note on page 8 in the table of predicted smoothed sunspot numbers that the optimistic faction predicts a sunspot minimum of 4 centered around December 2007-April 2008. The pessimistic projection is for a smoothed sunspot number minimum of 3 from January-April 2008.

Now compare this with the prediction ten weeks later on page 9 of issue 1697 from this week. See how the pessimists are now calling for a much longer and lower solar minimum lasting over a year, from November 2007-December 2008. But according to the optimists, the solar minimum has already passed, with a smoothed sunspot number of 6 in August and September 2007 (this generally agrees with our 3-month averages of daily numbers, presented in last week’s bulletin.)

Note there is no split in the value for August 2007. This is because 6 is the known smoothed sunspot number for that month, not a prediction. A year of daily sunspot numbers is required to calculate the smoothed value, and all of the values from mid-February 2007 through mid-February 2008 (a whole year with August in the middle) are known. In fact, enough sunspot data will be known this weekend to fix the smoothed sunspot number for September of last year.

Now look at even better news for sunspot fans. See how the predictions for the peak of the next solar cycle have shifted and both factions see Cycle 24 peaking much higher than they did 10 weeks earlier.

In issue 1687, pessimists predicted a peak between May and October 2012 of only 90, but now in issue 1697, we see a much higher and earlier peak at 124 from August-December 2011, only three and a half years from now. The optimists and pessimists now agree on the timing of the peak, and optimists have upped their peak value prediction from 140 to 154 (access all recent weekly issues here.)

Of course, with only 23 cycles of data to examine, sunspot cycle prediction is still a young science. But new tools unavailable in past decades no doubt have advanced the art.


Written by John A

March 15, 2008 at 7:40 am

Posted in Solar Cycle 24

4 Responses

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  1. Good post. Where the experts are found oracular we will be reminded. We need this documentation in the event they are not.
    And if they prove reasonably correct, I’m the Queen of France!

    Gary Gulrud

    March 16, 2008 at 5:36 pm

  2. Unfortunately, I am probably the bearer of bad news in pointing out that for August 2007 to have been the minimum, the rise in sunspot activity since then should have been led by spots with cycle 24 polarities. Since we have yet to see more than 2 cycle 24 spots and cycle 23 just produced 3 new spots including one with an M class flare, we are likely to be several months shy of the minimum yet. Until the cycle 23 coronal holes close up and the cycle 24 spots start to overtake the cycle 23 spots in number and size, we won’t likely see the minimum.

    Bill F

    March 25, 2008 at 10:22 pm

  3. Here is an interesting new study that you may want to address:


    April 3, 2008 at 11:51 am

  4. this link shows there is more to it than Sloan’s paper admits,

    Julian Braggins

    April 24, 2008 at 11:51 am

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