Solar Science

A blog of solar physics

Archive for March 2008

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

A couple of SC24 predictions

with 3 comments

David Archibald (as reported by Ronald Bailey at Reason magazine):

One of the more remarkable performances was by Australian entrepreneur David C. Archibald during one of the afternoon panels. Archibald is described in the conference materials as “a scientist operating in the fields of cancer research, climate science, and oil exploration.” He also appears to have business interests in some oil fields in Australia. In any case, Archibald made it very clear that he is a big believer in the idea that climate change is primarily driven by the sun. Archibald’s basic theory is that when the sun’s magnetic field strength drops there are fewer sunspots which reduce the amount of particles ejected as the solar wind. Less solar wind allows more galactic cosmic rays to enter the Earth’s atmosphere. Archibald is here relying on studies by Danish physicist Henrik Svensmark which find that cosmic rays do produce cloud condensation nuclei which then might create low level clouds that reflect more sunlight back into space thus making the Earth colder.

Archibald predicts that the next solar cycle, Cycle 24, will produce a weak magnetic field which means that more cosmic rays will enter the atmosphere to create clouds and thus cool the earth. Actually, a 2007 NASA scientific panel was evenly split on the strong/weak prediction for Cycle 24. However, manyresearchers expect that Cycle 25 may be one the weakest in centuries. Archibald ended by boldly predicting that the world will see average temperatures drop by -2.2 degrees centigrade in the coming decade. That’s more than three times the amount of warming the world has experienced over the last century. He also predicted as a consequence that the growing seasons in the United States would be shortened by a total of four weeks, dramatically reducing food production.

Piers Corbyn: astrophysicist and Earth weather predictor at Weather Action (personal communication):

…I would say that solar cycle 24 has NOT yet begun in the sense that we have not yet reached the smoothed minimum normally used to define the transition.

As far as the (Jan 3rd) NASA sighting (‘claim’?) of a reverse polarity spot, I don’t suppose there is any doubt that it was seen but I do agree with your implied statement that it doesn’t amount to much.

As a rough estimate we don’t expect any (more/lasting) reverse polarity spots until maybe shortly after mid-March at the earliest.

Paste this into your blog if you wish.

It will be worth referring back to these once SC24 has established itself in whatever form it turns out to be in.

Written by John A

March 5, 2008 at 9:12 am