Guest essay by David Archibald
This essay provides a series of graphs that describe the current state of the sun in context with its history.
Figure 1: Oulu Neutron Count 1964 – 2014
Cosmic rays are pushed away, to some extent, from the inner planets of the solar system by the Sun’s magnetic field carried in the solar wind.
Cosmic rays are mostly protons and alpha particles with some electrons and the nuclei of heavier elements. The highest energy cosmic rays have energies comparable to the energy of a 90 kmph baseball. As they hit oxygen and nitrogen atoms in the atmosphere, they cause a shower of neutrons. The neutron count from this source follows the solar cycle with about a one year lag, reflecting the time it takes for the solar wind to reach the heliopause. There is a connection with climate in that the atoms hit by the neutrons provide seed points for cloud formation.
A good proportion of the atmosphere is saturated with water above the cloud formation threshold but doesn’t form clouds due to lack of seed points to start the process of droplet formation. This is well illustrated by the satellite photos of clouds forming from ship tracks. Open ocean absorbs 95% of incident solar energy while clouds reflect 40%, so an increase in cloud cover will have a cooling effect. This effect accounts for a portion of climate variation with solar activity. The low in neutron count for this cycle appears to be in, consistent with solar maximum being in early 2013.
Figure 2: Solar Wind Flow Pressure 1971 – 2014
The solar wind flow pressure is now at a monthly high for Solar Cycle 24.
Figure 3: Ap Index 1932 – 2014
The Ap Index is a measure of geomagnetic activity from eight stations around the planet and reflects disturbances in the horizontal component of the Earth’s magnetic field. Activity for the current solar cycle has peaked at about the floor activity for the prior solar cycles back to early 1930s.
Figure 4: Heliospheric Current Sheet Tilt Angle
As measured by the heliospheric tilt angle, Solar Cycle 24 maximum was 19 months ago in March 2013.
Figure 5: Monthly F10.7 Flux 1948 – 2014
The F10.7 flux is a measure of the Sun’s emissions at 2800 MHz (10.7 cm) and correlates with sunspot number. It is a cleaner measure than sunspot number in that it is not subject to observer bias and the record can’t be adjusted on a whim. It has a floor at 64. Based on the correlation with sea level, a F10.7 flux above 100 is warming and below that is cooling. It has been consistently above that level since August 2011.
Figure 6: Interplanetary Magnetic Field 1966 – 2014
The interplanetary magnetic field has hit a new high for this solar cycle.
Figure 7: Interplanetary Magnetic Field 1 – 2014
This figure shows the data from Figure 6 combined with the reconstruction of the interplanetary magnetic field (IMF) for the last 2000 years by Steinhilber et al (data courtesy of Dr Gargett). It shows that the IMF is currently about the average for that period. The IMF has a lot further to fall to get to the levels of the major minima. We have all lived through the highest level of solar activity for 8,000 years and it was very pleasant. It will be real treat to live through a major minimum as well.
David Archibald, a Visiting Fellow at the Institute of World Politics in Washington, D.C., is the author of Twilight of Abundance: Why Life in the 21st Century Will Be Nasty, Brutish, and Short (Regnery, 2014)