Solar Min. Has Passed - What Now ?

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Roger, VK2ZRH

Tue Feb 24 2009, 12:16PM
In June last year, Australia's IPS Radio & Space Services forecast the Solar minimum would occur in October. From the latest figures on smoothed sunspot number (SSN) at , which are based partly on observed and partly on predicted values, it seems they were on the money. Here are the figures (Jan to Dec from left to right).

2008 4.2 3.6 3.3 3.3 3.5 3.2 2.7 2.7e 2.5e 2.3e 2.6e 2.9e
2009 3.4e

So, it seems Solar Cycle 23 will be 145 months long. Not the longest on record, but certainly one of the longer ones.

Keeping in mind the mean solar cycle of 133 months, Cycle 23 beats Cycle 20 (which peaked in 11/1968; SSN = 110.6) at 140 months, and Cycle 13 (peaked in 1/1894; SSN = 87.9) at 143 months. However, in the 300-year record of solar cycles, the longest have been around 168 months - 14 years!

For a different view of when the Solar minimum occurred, see the Solar Influences Data analysis Center (SIDC, Brussels) latest Solar Bulletin , which puts it at either August through October, or August (depending on the method of calculation).

With the smoothed sunspot number in October at 2.3 (IPS), this compares with Cycle 12 (3/1878 to 12/1890) when the SSN at minimum hit 2.2, or Cycle 15's (8/1913 to 8/1923) SSN minimum of 1.5 !

It begs the question: do low minima precede low maxima . . . or high maxima ? Answer: sometimes !

The 1.5 SSN of 8/1913 preceded a maxima of 105.4 in 8/1917 (rather below the average of 120.5 of Cycles 9 through 23). However, 9 of the minimum SSNs over the past 15 Cycles have been below the average of 6.3; Cycles 18, 20, 21, 22 and 23 had minima above the average . . . as did Cycle 9.

The 4/1954 minimum of 3.4 preceded the Cycle 19 maximum of 201.3 ! The 12/1878 minimum of 2.2 preceded the Cycle 12 maximum of 74.6. :( However, the 8/1913 minimum of 1.5 preceded the 105.4 maximum of 8/1917.

So, after a run of high minima, we've had a low minima . . . optimists should pray that observed sunspot numbers keep rising !

73, Roger Harrison VK2ZRH
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Steve, VK3OT
Tue Sep 22 2009, 10:31AM
Steve, VK3OT
Registered Member #418
Joined: Tue May 20 2008, 10:10AM

Posts: 21
Well they haven't Roger, maybe the scientists can try for take three.
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