Guest essay by David Archibald
Two useful things we would like to know are the length of Solar Cycle 24 and the amplitude of Solar Cycle 25. Figure 1 below shows the NOAA version of Solar Cycle 24 progression with the 23/24 transition copied onto the end of their projection. This crude method (we don’t have another) suggests that the 24/25 transition will be at the end of 2021 which would make Solar Cycle 24 twelve years long. Solar physicists have generally given up forecasting Solar Cycle 25 amplitude. The only extant forecast is Livingstone and Penn’s forecast of an amplitude of seven. In the bigger picture, almost a decade after Schatten and Tobiska forecast a return to a Maunder Minimum-like level of activity, another solar physicist, Mark Giampapa of the National Solar Observatory in Tuscon, Arizona, is of the opinion that “we are heading into a Maunder Minimum” that could last until 2080.
Figure 1: Solar Cycle 24 Progression
Figure 2: Interplanetary Magnetic Field
While in recent days the surface of the Sun became almost blank of sunspots, some solar activity parameters have taken off. The interplanetary magnetic field reached a peak higher than it reached during Solar Cycle 20.
Figure 3: Solar Wind Flow Pressure
Similarly, solar wind flow pressure is now higher than it was during most of Solar Cycle 23.
Figure 4: Oulu Neutron Count
Neutron count generally takes a year to respond to the solar wind flow pressure and the interplanetary magnetic field so we may not have seen the lows in neutron count for this solar cycle. That may be in mid-2016. Solar Cycle 24 may be going stronger for longer, to borrow a term from the financial community.
Figure 5: Heliospheric Current Sheet Tilt Angle
All we can say at the moment from this figure is that Solar Cycle 24 seems to have had a broader top than any of the previous three cycles.
Figure 6: Sum of Solar Polar Field Strengths
The magnetic poles of the Sun reverse at solar maximum when the sum of the polar field strengths falls to near zero. Sunspot activity showed a double top for Solar Cycle 24 and this is supported by Figure 6 which shows that the Sun had about a year at solar maximum.
Figure 7: North America Ex-Greenland Monthly Snow Cover
Onset of an ice age requires snow to survive through the summer and cool the earth due to its higher albedo. Despite the recent cold winters, we have yet to see summer snow survival get back to the levels of the 1970s cooling period.
Figure 8: Lebanon, New Hampshire Average Monthly Temperatures 2000 – 2015
As a followup to this post on the cold start to the year in Maine, this figure shows average monthly temperature for Lebanon, New Hampshire just to the west of Maine. The years 2000-2014 are used as the reference period as this is the period of the pause and people’s most recent personal reference point. The year 2015 to date is shown as the dark blue smoothed line. February 2015 was 12.1°F colder than the average for the fifteen year of 2000-2014 with an average of 11.6°F. This is the second coldest February back to 1900 with the coldest being 1934 at 8.1°F.
The biggest dispersion in average monthly temperatures is in January and then it tightens up such that the spread in June is only 3°F. The temperature for April was back in the pack though 1.3°F cooler than the average of the prior 15 years. All that can be said is that it will be interesting to see how it goes.
David Archibald, a visiting fellow at the Institute of World Politics in Washington, D.C., is the author of Twilight of Abundance (Regnery, 2014)