Last week NOAA introduced a newly revamped graph for tracking the monthly activity of sunspots on the Sun’s visible hemisphere. (You can see an example of the old graph, used by them for more than fifteen years, here.)
In order to properly understand the context of future sunspot activity, it is important to understand how the new graph aligns with the old. My first attempt to do so in my April 3, 2020 sunspot update, unfortunately was a failure. While most of my conclusions in that update remain correct, my attempt to place NOAA’s prediction for the next solar cycle on my graph was in error.
I had not realized that NOAA had changed its sunspot number scale on graph’s vertical axis. In their old graph they had used the monthly sunspot number count from the Royal Observatory of Belgium. The new graph instead used the sunspot number from NOAA’s own Space Weather Prediction Center (SWPC). Both numbers are creditable, but the solar scientist community has switched entirely to the latter in the past few years because they consider its criteria for determining the count across all past cycles to be more accurate.
The Belgium numbers have traditionally been about one third lower than SWPC’s. Not realizing that NOAA’s new prediction,was based on the SWPC numbers. I therefore placed it on the graph using the Belgium numbers and thus made the peak of the solar maximum 33% too high.
Below is NOAA’s new graph, annotated properly with both the past and new solar cycle predictions added now correctly.
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