dimanche 5 octobre 2008
Sunspots for the last 10,000 years and more
Above is a Morlet continous wave transformation for sunspots . Another can be seen here http://wattsupwiththat.files.wordpress.com/2008/09/wavelet_ssn.png
Time is read along the horizontal axis, and a time scale is drawn across the top of the image. Frequency is read on the verticle axis. The scale is 2**x months, where is is 1,2,3..9. So 2**7 is 128 months. Amplitude is indicated by color. The basic 11 year Schwabe cycle is clearly indicated by the red ovals bisected by the line for 11 years. I’ve noted the Dalton Minimum, which is clearly different in character than the other cycles — with weaker and longer solar cycles. It is subtle, but you can see the weaker intensity of solar cycles 10-15 compared to solar cycles 16-23 in the weaker color of the earlier cycles. There is clearly enhanced activity, and of longer duration, at the end of the 20th century.
There is also a weaker, but distinct, level of activity at 22 years, the double sunspot of Hale cycle. The last three Hale cycles have been stronger than earlier Hale cycles. There is some indication of a double Hale cycle (~44 years) and at the top of the graph, we’re in Gleissberg cycle territory.
Now, for an interesting observation and speculation, note that at present, which is at the right edge of the chart, from the 11 yr line to the top it is all blue. There is only one other place on the entire chart where we can draw a vertical line from the 11 yr line to the top without it crossing some portion of color other than blue. Can you find it? (It is right at the beginning of Solar Cycle 5, i.e. the Dalton Minimum). Are we watching the beginning of a new 200 year cycle like what began with the Dalton Minimum in the early 1800’s? Obviously, no one knows. But the current transition is certainly unusual, and invites comparison to past transitions.
This is a Morlet continous wave transformation for sunspots for the last
This is the data set used to produce the wavelet.
Solanki, S.K., I.G. Usoskin, B. Kromer, M. Schüssler and J. Beer. 2004. An unusually active Sun during recent decades compared to the previous 11,000 years. Nature, Vol. 431, No. 7012, pp.1084-1087, 28 October 2004.
The diagram above is for the data set here
This data appeared at http://wattsupwiththat.com/2008/09/22/new-cycle-24-sunspot/ and It's thanks to Basil (I only know his tag) that I managed to figure it out. I used the PAST programme to do so.
What does it show? Time is on the Horizontal axis and intensity on the vertical one. Well the ice age looks good.... Nice and blue. (between 240 and 600?) Compare it to The Dalton minimum which is clearly visible on the top graph.