The sunspot number for February from SIDC is down again, to 33.1. While the delta of the drop in Feb 2012 is not unusual by itself, it is the lowest observed value of the last three cycles this far into a new cycle.
Here’s the source of that data: http://sidc.oma.be/DATA/monthssn.dat
So far, cycle 24 is significantly lower in SSN number that the last three cycles, in addition to having a delayed start. While the delta of the drop in Feb 2012 is not unusual by itself, it is the lowest observed value of the last three cycles this far into a new cycle.
Compared to the entire data set back to 1749, which I’ve plotted below…
…it shows cycle 24 so far to be on par with cycle 12 and cycle 6 in amplitude.
While this drop in SSN number might appear to some as a signal for a possible peaking of cycle 24, there is other evidence that suggests otherwise. For example the Solar Polar Field Strength. Usually the polarity of the North and South solar hemispheres flips at solar max. As you can see in the graph we are close but not quite there yet. And, it has flattened out compared with previous recent transitions.
Leif Svalgaard also tracks this and here are a couple of his graphs:
Leif has previously suggested that he thinks for solar polar field will see the flip later 2012 or early 2013. We don’t have long to wait.
NOAA’s Space Weather Prediction Center (SWPC) has not yet updated their Solar Cycle Progression page, but will in a few days. In the meantime, here are the SSN and Ap index graphs manually updated with SIDC data to give you an idea of what they will look like compared to the forecast (in red):
The Ap Geomagnetic field index, just like the SSN, is down again, suggesting the sun’s magnetic dynamo is not winding up like it did near the peak of cycle 23 and previous cycles.
We live in interesting times.