Guest post by David Archibald
Solar Cycle 24 has already seen five consecutive colder winters. This is a link to a post about a German meteorologist who has seen the light. Eventually people will work their way back to where all the energy comes from. The amount and type of energy coming from the Sun varies on time scales up thousands of years. Now that we are somewhere near the peak of Solar Cycle 24, let’s see how things are progressing.
Figure 1: MF, TSI, F10.7 Flux and Sunspot Number 2009 – 2013
From Dr Svalgaard’s site, this figure shows that the F10.7 flux is hovering around 100, which is the breakover point between sea level rising and sea level falling. In turn that also means it is the breakover point between the planet warming and the planet cooling. Given that activity will drop once we pass solar maximum, cooling is in train from here.
Figure 2: Heliospheric Current Sheet Tilt Angle 1976 – 2012
The heliospheric current sheet tilt angle was at 70.6° as at November 2012. Solar maximum occurs when it reaches 74° – so a little bit further to go.
Figure 3: Ap Index 1932 – 2013
The Ap Index has fallen back below the levels of previous solar minima.
Figure 4: Solar Wind Flow Pressure 1971 – 2012
The solar wind flow pressure has also seen its peak for this cycle.
Figure 5: Oulu Neutron Count 1964 – 2013
The neutron count is likely to trend sideways for another year before rising to a new peak for the instrumental record.
Figure 6: Interplanetary Magnetic Field 1968 – 2013
The Interplanetary Magnetic Field appears to have peaked for this cycle.
Figure 7: Solar Cycle 24 Sunspot Number compared to the Dalton Minimum
This chart compares the development of Solar Cycle 24 with the Dalton Minimum. The Solar Cycle 24 is tracking Solar Cycle 5 very closely.
Figure 8: Solanki Sunspot Number Reconstruction 9455 BC to 2035 AD
The data is from Solanki et al 2004 “Unusual activity of the Sun during recent decades compared to the previous 11,000 years”, courtesy of David Evans. A projection to 2035 is included based on Livingstone and Penn’s estimate of an amplitude for Solar Cycle 25 of 7. The average annual sunspot number in Solanki’s reconstruction is 28.7. The average annual sunspot number for the second half of the 20th century is 72.
Figure 9: Solanki cumulative sunspot reconstruction
This graph takes the data from Figure 7 and is additive relative to the average sunspot number over the period of 28.7. It shows that solar activity trends for thousands of years at a time.
Figure 10: Steinhilber et al TSI reconstruction 7,362 BC to 2007 AD
Similarly, Steinhilber et al reconstruction TSI relative to 1,365.57 W/m2 with data courtesy of David Evans.
Figure 11: Steinhilber et al TSI reconstruction cumulative
This graph takes the data from Figure 9 and plots it cumulatively. It also shows that solar activity trends for thousands of years. The Steinhilber reconstruction does show the beginning of the Dark Ages cold period and the Little Ice Age quite accurately.