Written by Jeff Id
January 19, 2009
A guest post by Jeff Id
Well John Christy gave me a lot to think about in satellite temp trends as far as an improved correction over my last post. Steve McIntyre pitched in some comments as well. It is going to take a bit to work out the details of that for me but I think I can produce an improved accuracy slope over my last posts. In the meantime, I downloaded sunspot numbers from the NASA.
Cycles are interesting things. There are endless cycles in nature, orbits, ocean temp shifts, solar cycles, magnetic cycles the examples are everywhere. What makes a cycle unusual is also an interesting topic. Some solar scientists have claimed that our current solar cycle is not unusual by the record. They are certainly the experts but recently the experts have been forced to update their predictions for the next solar cycle.
Well, I'm no expert on the sun but I do find the data regarding sunspots interesting, particularly in the fact that we are again in at least a short term cooling at the same time sunspots and solar magnetic level have plunged.
Here's an article from our all understanding US government.
What's Wrong with the Sun? (Nothing)
And a few beginning lines.
July 11, 2008: Stop the presses! The sun is behaving normally.
So says NASA solar physicist David Hathaway. "There have been some reports lately that Solar Minimum is lasting longer than it should. That's not true. The ongoing lull in sunspot number is well within historic norms for the solar cycle."
Cool picture .......
See where the tiny little 2009 tick is. We should be increasing now and well on our way by 2010. By the way, this is an updated graph from the original predition.
Hathaway said, well within historic norms. Forecasting is the most dangerous sport, but I am as curious about this claim as any -he is the expert after all. Here's a plot of the sunspot data from NASA NOAA numbers.
I did a sliding slope fit to the data to find when the slopes shifted from negative to positive in each cycle. I placed a red line above each point identified. These points are not intended to mean the beginning of a cycle( that is for the experts) but rather to be a consistent software identified point between each cycle.
The red lines represent solar minima. The only line which may not be a minima is the most recent in Jan 09 which we need to reference how unusual solar activity is.
Below is a list of the years the red lines are centered on.
1755.667, 1766.250. 1775.583, 1784.500, 1798.167, 1810.583, 1823.167, 1833.833, 1843.833, 1856.167, 1867.167, 1878.750
1889.500, 1901.750, 1913.167, 1923.417, 1933.750, 1944.167, 1954.250, 1964.833, 1976.250, 1986.250, 1996.417, 2009.041
The years between each minima are currently
10.583, 9.333, 8.916, 13.666, 12.416, 12.583, 10.666, 10.000, 12.333, 11.000, 11.583, 10.750, 12.250, 11.416, 10.250, 10.333,
10.416, 10.083, 10.583, 11.416, 10.000, 10.166, 12.625
So far there has been only one solar cycle which has exceeded the length of the current one. The cycle extended extra long (13.66 years) from 1784 - 1798 and was the last cycle leading into the Dalton Minimum.
A histogram of the distribution of the time between solar cycles looks like this.
The standard deviation of the total record is 1.18 years the mean is 11.01. Well there's the eleven year solar cycle we hear about.
Two sigma (two standard deviation) difference from the mean corresponds to a 95% certainty of something unusual in our current situation. The numbers this year at mid Jan correspond to about 1.37 sigma of all time records, which is getting close. But that's not the end of the story, after all I just included the dalton minimum cycles in the data right after we identified the solar cycle prior to the dalton minimum as the one with the longest time span on record. That means, I treated it as though it were a normal event. -- Well I do believe (on faith in nature) this length is normal, the sun isn't doing anything different from before but there is only one of these long events on record and were we to look for a similar event it would be stupid to include it in the standard deviation dataset. We should only look at data which is not related to another potential dalton minimum from Figure 2 this would be after the dalton minimum and before present day (from 1833 - 1996).
The standard deviation of the cycle start after the dalton minimum 1833 and before 2009 was only 0.79 years. The average Jeff Id solar cycle in the same period is 10.83 years. This puts the two sigma limits of the solar cycle at 9.26 years on the short side and 12.42 years on the long side.
Of course this puts my reasonable analysis of solar cycle outside of the last 176 year normal to a two sigma 95% interval 12.6 years has crossed the limit. With little sign of the next cycle beginning yet, this might get worse. I tell you what, I prefer the taxes from global warming to the cost of glaciers in my yard, it seems like a balance of evils to me. I hope this solar cycle changes soon but we can no more effect the sun with a dance than we can effect global warming with a tax so what choice do we have.
In Dr. David Hathaway's defense, he made his statement above in July which put the current minimum at 2008.583 which comes to 12.166 years and just inside the 95% two sigma certainty of 12.42.
Now that we're at 12.6, I wonder if they'll extend the predictions for the beginning of the next cycle again.