Guest essay by David Archibald

Our divination of solar parameters is aimed to elucidating two things – the length of Solar Cycle 24 and the amplitude of Solar Cycle 25.

Figure 1: F10.7 Flux from 2014

The F10.7 flux was exhibiting high volatility up to the beginning of 2015 after which it entered a disciplined decline in activity to late 2016. Now it is not far above the activity floor of 64 with three years of the solar cycle to go.

Figure 2: Solar Cycle 24 progression relative to Solar Cycles 19 to 23

For the last couple of years Solar Cycle 24 has been bumping along the lower bound of activity for the cycles for which we have F10.7 data, but with much lower volatility. From here it looks like Solar Cycle 24 will have a long, flat tail until minimum.

Figure 3: Interplanetary Magnetic Field 1966 to 2017

Combined with the solar wind flow pressure, the magnetic field coming out of the Sun is what pushes galactic cosmic rays away from the inner planets of the solar system. Activity in Solar Cycle 24 was backloaded but is now down to levels of previous solar minima.

Figure 4: Oulu Neutron Count 1964 – 2017

The neutron flux, caused by galactic cosmic rays hitting oxygen and nitrogen atoms in the atmosphere, causes changes in cloudiness by providing nucleation sites for cloud droplets. Changes in cloud cover in turn cause change in the Earth’s albedo, perhaps the largest driver of climate. The neutron count is climbing fast now that the peak in the interplanetary magnetic field (and Ap Index and solar wind flow pressure) has passed.

Figure 5: Solar Cycles aligned in month of solar minimum

Solar Cycle 24 is the cycle in blue at the top of the figure. It is three years ahead of Solar Cycle 23 at the same level of neutron flux. It also looks like it will have a higher count than Solar Cycle 20 which caused the 1970s cooling period.

Figure 6: Circum-Arctic oceans temperatures 2004 to 2017

The Climate4you site carries a graphic of circum-Arctic ocean temperatures from the surface to 1,900 metres using Argo data. What is interesting is that the water depth slice from from 200 metres to 1,500 metres is showing a strong and consistent cooling trend from 2012. The slice from 400 metres to 1,200 metres is shown above. The temperature decline at 1,000 metres has been 0.1°C per year from 2012.

Figure 7: Solar Polar Magnetic Field Strength by Solar Cycle and aligned on solar minimum

Solar polar magnetic field strength at solar minimum is the best indication of the amplitude of the following solar cycle. With an amplitude similar to that of Solar Cycle 23 at the same stage, it looked like Solar Cycle 25 might be just a little weaker than 24. It is still too early to tell.

David Archibald is the author of American Gripen: The Solution to the F-35 Nightmare.

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