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Correction! For reasons I do not understand, the graph below, originally posted on the NOAA website, was incorrect and was changed several days after I posted my piece below. See this post for the correct graph and analysis.
The uncertainty of science: On Monday NOAA posted its monthly update of the solar cycle, showing the Sun’s sunspot activity in September. Once again I post it here, below the fold, with annotations to give it context.
For the third month in a row the sunspot count dropped a tiny amount, lingering at about the same number as the previous two months. Moreover, the rate of decline seems to have transitioned down from the 2009 prediction (red curve) to the 2007 weak prediction (lower green curve). This doesn’t real mean much, as the sunspot number can still vary up and down considerable before we reach solar minimum in two or three years.
The graph above has been modified to show the predictions of the solar science community. The green curves show the community’s two original predictions from April 2007, with half the scientists predicting a very strong maximum and half predicting a weak one. The red curve is their revised May 2009 prediction.
The decline to solar minimum is now beginning resemble previous ramp downs. If you compare this ramp down with the previous cycle, shown on the graph, you can see that the last cycle started its ramp down very quickly, then slowed to a long gradual decline over almost six years. It appears that this might be what is happening with this cycle as well.