Sometime ago, every month I blogged a brief report on the activity of the Sun. I have the urge to do that again, so here goes.
Solar Cycle (SC) 24 has just about run its course. It is forecast to give over to SC 25 in late 2019/early 2020 and when it does, that’s call the 24SC minimum.
Sunspots are a proxy for Solar activity. The chart below shows the average number of sunspots in each month. The blue dashed line is a 13-month averaged sunspot count. It is the official sunspot number. (The formula for the count is shown at the end of this posting.) The official number of sunspots peaked in April of 2014 thus the solar maximum happened then.
The chart below illustrates how recent SCs compare to SC 24:
All three of the preceding SCs were much more active than SC24.
As side note, the SCs on average last for 11 years, or saying another way, 132 months. At one time, it was believed that if the SC was over before 11 years it was generally an active SC. More than 11 years, less active.
The chart below shows the 24 SCs and the chart makers attempt at a SC25. The X axis is in years from 1749 to an estimated 2040. The Y axis is sunspots
One can see that SCs 23, 22, 21, 19, and 18 represent a very active sun. The maker of the chart calls this the “modern warm period”. Looking back the chart maker has noted the time of the “Dalton Minimum” and the “little ice age”. These periods of low solar activity coincide with the periods of low global temperatures. Perhaps you can see why many scientists are forecasting that global temperatures will soon be dropping. Also one can speculate that the global warming we have experienced may be a product of the past 60 years of a very active sun. Ok, now one more reading of the chart might suggest that we are due for a period of low solar activity thus a drop in global temperatures. The chart maker’s projection of SC 25 to be lowest in recorded history is very likely to be wrong. However the batting average of the predictors of future SCs is not too stellar so who knows.
Throughout the recent past, claims were made that the global temperature was going to drop because SC 24 was relatively inactive. I do not think that the temperature did drop. I believe I read one article where the claim was that SC 24 was the reason that the increased CO2 in the atmosphere did not raise the temperature as much as it should have. I don’t believe that one.
Was SC 24 definitely an uniquely quiet SC? I think so.
The sunspot activity of the cycles in comparison. The numbers in the diagram are obtained by summing the monthly differences between the observed SSN and the mean (blue in Fig.1) up to the current cycle month 125. ( I am not sure whom to attribute this chart but I got it from Prof. Fritz Vahrenholt and Frank Bosse who write the diekaltesonne blog.)
This shows that at just about 10-1/2 years, SC 24 has had 4464 fewer sunspots than the average SC. It also shows that SCs 5 and 6, had the fewest sunspot and those two SC are coincident with the Dalton Minimum. SC 12, 13, 14, 15, and 16 were way low on sunspots and they coincided with the little ice age.
It is clear that the sun was much less active as demonstrated by the sunspot record. I expected a clear sign by the end of its cycle, which we have not yet seen, of a cooling global temperature trend. Some think we have that, but I do not see what I expected from the UAH satellite global temperature readings. The temperature has declined since the last El Nino but it has not been lowered to the temperature before that El Nino.
Next a look at Solar Cycle 25.
Sunspot Counting–Woolf Number
The smoothed count is a 13-month averaged sunspot count using this Belgium’s formula:
Rs= (0.5 Rm-6 + Rm-5 + Rm-4 + Rm-3 + Rm-2 + Rm-1 + Rm + Rm+1 + Rm+2 + Rm+3 + Rm+4 + Rm+5 + 0.5 Rm+6 ) / 12
Rs = smoothed monthly sunspot count
Rm = One month’s actual sunspot count
The “-6” through “+6” appended to each Rm is the number of months before or after the month whose smoothed count is being calculated. The beginning and ending months in the formula are only given half the value of the others.*