Posts Tagged ‘Sunspot Number’

Solar Cycle 24 passes maximum? Low sunspot numbers and climate cooling indicated for next two cycles

February 11, 2015

It is not completely certain but it does look like Solar Cycle 24 has just passed its maximum. The maximum was initially expected to be reached in late 2012 and gradually drifted to late 2013. Now it would seem that this may not have occurred till late 2014.  While the minima at the beginnings of SC 23 and 24 seem to have been c. 12 years apart, the maxima are closer to 14 years apart.

SC24 2015 January  From NASA Hathaway

SC24 2015 January From NASA Hathaway

The length of Solar Cycles is thought to be linked to the solar activity to be expected in the following 2 cycles. Periods much longer than the average of 11.2 years seem to lead to decreased subsequent activity, lower sunspot numbers and also lower global temperatures.

Solheim et al predicted lower sunspot activity and cooler times during SC 24. Now it would seem this will also be the prevailing paradigm through SC25 and perhaps even SC26. Another two decades of reduced sunspot activity and a global cooling carried by the ocean cycles would seem to be on the cards.

Abstract

Relations between the length of a sunspot cycle and the average temperature in the same and the next cycle are calculated for a number of meteorological stations in Norway and in the North Atlantic region. No significant trend is found between the length of a cycle and the average temperature in the same cycle, but a significant negative trend is found between the length of a cycle and the temperature in the next cycle. This provides a tool to predict an average temperature decrease of at least 1.0ºC from solar cycle 23 to solar cycle 24 for the stations and areas analyzed. We find for the Norwegian local stations investigated that 25–56% of the temperature increase the last 150 years may be attributed to the Sun. For 3 North Atlantic stations we get 63–72% solar contribution. This points to the Atlantic currents as reinforcing a solar signal.

They write:

The length of a solar cycle is determined as the time from the appearance of the first spot in a cycle at high solar latitude, to the disappearance of the last spot in the same cycle near the solar equator. However, before the last spot in a cycle disappears, the first spot in the next cycle appears at high latitude, and there is normally a two years overlap. The time of the minimum is defined as the central time of overlap between the two cycles (Waldmeier, 1939), and the length of a cycle can be measured between successive minima or maxima. A recent description of how the time of minimum is calculated is given by NGDC (2011): “When observations permit, a date selected as either a cycle minimum or maximum is based in part on an average of the times extremes are reached in the monthly mean sunspot number, in the smoothed monthly mean sunspot number, and in the monthly mean number of spot groups alone. Two more measures are used at time of sunspot minimum: the number of spotless days and the frequency of occurrence of old and new cycle spot groups.”

It was for a long time thought that the appearance of a solar cycle was a random event, which means that each cycle length and amplitude were independent of the previous. However, Dicke (1978) showed that an internal chronometer has to exist inside the Sun, which after a number of short cycles, reset the cycle length so the average length of 11.2 years is kept. Richards et al. (2009) analyzed the length of cycles 1610–2000 using median trace analyses of the cycle lengths and power spectrum analyses of the O–C residuals of the dates of sunspot maxima and minima. They identified a period of 188±38 years. They also found a correspondence between long cycles and minima of number of spots. Their study suggests that the length of sunspot cycles should increase gradually over the next ~75 years. accompanied by a gradual decrease in the number of sunspots.

An autocorrelation study by Solanki et al. (2002) showed that the length of a solar cycle is a good predictor for the maximum sunspot number in the next cycle, in the sense that short cycles predict high Rmax  and long cycles predict small Rmax. They explain this with the solar dynamo having a memory of the previous cycle’s length.

Assuming a relation between the sunspot number and global temperature, the secular periodic change of SCL may then correlate with the global temperature, and as long as we are on the ascending (or descending) branches of the 188 year period, we may predict a warmer (or cooler) climate.

It was also demonstrated (Friis-Christensen and Lassen, 1992, Hoyt and Schatten, 1993 and Lassen and Friis-Christensen, 1995) that the correlation between SCL and climate probably has been in operation for centuries. A statistical study of 69 tree rings sets, covering more than 594 years, and SCL demonstrated that wider tree-rings (better growth conditions) were associated with shorter sunspot cycles (Zhou and Butler, 1998).

Solar Cycle 24 has passed its maximum – 25 years of cooling to be expected in this Landscheidt minimum

October 4, 2013

The September sunspot numbers are now out and it would seem that Solar Cycle 24 has passed its maximum. It looks very much like SC23, SC24 and the coming SC25 will be comparable to SC4, 5 and 6. Solar Cycles 5 and 6 were responsible for the Dalton Minimum. SC 24 and 25 will constitute the Landscheidt Minimum and we can now expect some 25 additional years of global cooling (which has of course already started – about 6 or 7 years ago).

LSC: This month was recorded as the lowest month since Jan 2011 which was the beginning of the rampup for SC24. Cycle max is close or passed with the northern hemisphere changing polarity and the south still somewhat floundering. The southern hemisphere just outweighing the northern hemisphere, showing the south is not meeting expectations by some that a second peak will occur. … SIDC 36.9, NOAA unadjusted at 55.0 (prov). 

NASA has made its latest prediction:

SC24 prediction October 2013

SC24 prediction October 2013

The transition from SC 23 to SC 24 looks very similar to that from SC4 to SC5.

SC4-6 and Dalton

SC4-6 and Dalton

Of course the IPCC makes little of any solar effects and while the variation of direct total irradiance is small, they are rather nonchalant about the very many profound ways in which solar effects manifest themselves in climate (via cloud formation and ocean cycles for example). But the global warmists and the IPCC have now so much invested in their increasingly dubious hypothesis that they are prepared to make the most convoluted contortions to deny the hiatus and that global cooling has started.

Judith Curry: 

Section 8.4.1 of the IPCC AR5 Report provides 2 pages of discussion on observations of solar irradiance.  But they conclude that all this doesn’t matter for the climate.  I agree that the TSI RF variations are much less than projected increased forcing due to the GHG.  But the solar-climate connection is probably a lot more complex than this statement implies. …..

…. Henrik Svensmark has an essay While the Sun Sleeps, …..

Solar activity has always varied. Around the year 1000, we had a period of very high solar activity, which coincided with the Medieval Warm Period. But after about 1300 solar activity declined and the world began to get colder. It was the beginning of the episode we now call the Little Ice Age.

It’s important to realise that the Little Ice Age was a global event. It ended in the late 19th Century and was followed by increasing solar activity. Over the past 50 years solar activity has been at its highest since the medieval warmth of 1000 years ago. But now it appears that the Sun has changed again, and is returning towards what solar scientists call a “grand minimum” such as we saw in the Little Ice Age.

The match between solar activity and climate through the ages is sometimes explained away as coincidence. Yet it turns out that, almost no matter when you look and not just in the last 1000 years, there is a link. Solar activity has repeatedly fluctuated between high and low during the past 10,000 years. In fact the Sun spent about 17 per cent of those 10,000 years in a sleeping mode, with a cooling Earth the result.

You may wonder why the international climate panel IPCC does not believe that the Sun’s changing activity affects the climate. The reason is that it considers only changes in solar radiation. That would be the simplest way for the Sun to change the climate – a bit like turning up and down the brightness of a light bulb.

Satellite measurements have shown that the variations of solar radiation are too small to explain climate change. But the panel has closed its eyes to another, much more powerful way for the Sun to affect Earth’s climate. In 1996 we discovered a surprising influence of the Sun – its impact on Earth’s cloud cover. High-energy accelerated particles coming from exploded stars, the cosmic rays, help to form clouds.

[C]limate scientists try to ignore this possibility.  If the Sun provoked a significant part of warming in the 20th Century, then the contribution by CO2 must necessarily be smaller.

The outcome may be that the Sun itself will demonstrate its importance for climate and so challenge the theories of global warming. No climate model has predicted a cooling of the Earth – quite the contrary. ….

 

 

 


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