21 Apr 09 - Paul Stanko of NOAA writes meteorologist Anthony Watts to tell him of an interesting development in his tracking of the International Sunspot Number (ISN).
Paul writes:
My running mean of the International Sunspot Number for 2009 just dipped below 1.00. For anything comparable you now need to go back before 1913 (which scored a 1.43) which could mean we're now competing directly with the Dalton Minimum. Just in case you'd like another tidbit, here is something that puts our 20 to 30 day spotless runs in perspective… the mother of all spotless runs (in the heart of the Maunder Minimum, of course!) was from October 15, 1661 to August 2, 1671. It totaled 3579 consecutive spotless days, all of which had obs. To say that that we in interesting times is a huge understatement. We are about to enter a Grand Minimum, which in the past have produced a cooler planet, while our government is preparing for run-away global warming. Who could have predicted this stupidity?
Is a new Dalton Minimum approaching?
Russ Steele
Well 2008 arrived last night and Sunspot Cycle 24 was absent. While we had a flurry of excitement a few week ago when a patch of reverse polarity showed on the Suns surface it soon faded. The Sun reverses polarity with each cycle change. As we have discussed in the past the length of the roughly 11-year sunspot cycle is correlated with temperature and a late arriving cycle can have some long term climate implications for us folks here on Earth. The Cycle 23 solar minimum was at 1996.5, so with an average 11 year cycle we should have seen the new minimum in mid-2007. Here we are in 2008 and the next cycle is already six months late, and the defining minimum generally occurs 12-20 months after the first spot of the new cycle. This would indicate the ending minimum of Cycle 23 and the start of Cycle 24 will come in mid 2009, resulting in a 13 year cycle, the longest since 1784-1797. Interesting to note that this cycle started a long series - 13.6, 12.3, 12.7 years, which coincided with the cold period known as the Dalton Minimum. Stay tuned, these are going to be interesting times. Sun cycles indicate cooling and the politicians are trying stop global warming. We may need a little extra warming over the next thirty years.
Thanks to David Archibald for this graphic showing the relationship of cycle length to temperature in New Hampshire.
The Dalton minimum in the 400 year history of sunspot numbers The Dalton Minimum was a period of low solar activity, named for the English meteorologist John Dalton, lasting from about 1790 to 1830. Like the Maunder Minimum and Spörer Minimum, the Dalton Minimum coincided with a period of lower-than-average global temperatures. The Oberlach Station in Germany, for example, experienced a 2.0° C decline over 20 years. The Year Without a Summer, in 1816, also occurred during the Dalton Minimum.
