The stunning announcement made at the annual meeting of the American Astronomical Society exceeded the expectations from the advance publicity!
The results of new studies were announced today (June 14) at the annual meeting of the solar physics division of the American Astronomical Society, which is being held this week at New Mexico State University in Las Cruces.
The results of three separate studies seem to show that even as the current sunspot cycle (SC24) moves toward the solar maximum, the sun could be heading into a more-dormant period, with activity during the next 11-year sunspot cycle (SC25) greatly reduced or even eliminated.
The indicators have been growing for some time that we are in for a a new solar minimum – the Landscheidt minimum – which could be similar to the Dalton Minimum and may even approach the Maunder Minimum. This could mean a cooling period for the earth of 20 – 30 years or for as long as 60 – 70 years. In any event the signs will be unambiguous and inescapable within a decade.
It is reasonable to assume that climatic conditions over the next 20 – 30 years will resemble those prevailing between 1790 and 1820. But SC24 has a way to go yet and it could be that solar activity for SC24 and 25 will be even lower than during the Dalton minimum and perhaps closer to the Spörer minimum but perhaps not as deep as the Maunder minimum.
But in either case the solar activity to come following the Modern maximum may well resemble the 500 years of decline in solar activity which followed the Medieval maximum.
Solar activity events recorded in radiocarbon. Present period is on left. Values since 1950 not shown: Wikipedia
The three papers are:
- “Large-Scale Zonal Flows During the Solar Minimum — Where Is Cycle 25?” by Frank Hill, R. Howe, R. Komm, J. Christensen-Dalsgaard, T.P. Larson, J. Schou & M. J. Thompson.
- “A Decade of Diminishing Sunspot Vigor” by W. C. Livingston, M. Penn & L. Svalgard.
- “Whither Goes Cycle 24? A View from the Fe XIV Corona” by R. C. Altrock.
Major Drop In Solar Activity Predicted
As the current sunspot cycle, Cycle 24, begins to ramp up toward maximum, independent studies of the solar interior, visible surface, and the corona indicate that the next 11-year solar sunspot cycle, Cycle 25, will be greatly reduced or may not happen at all.
“This is highly unusual and unexpected,” Dr. Frank Hill, associate director of the NSO’s Solar Synoptic Network, said of the results. “But the fact that three completely different views of the Sun point in the same direction is a powerful indicator that the sunspot cycle may be going into hibernation.”
Hill is the lead author on one of three papers on these results being presented this week. Using data from the Global Oscillation Network Group (GONG) of six observing stations around the world, the team translates surface pulsations caused by sound reverberating through the Sun into models of the internal structure.
One of their discoveries is an east-west zonal wind flow inside the Sun, called the torsional oscillation, which starts at mid-latitudes and migrates towards the equator. The latitude of this wind stream matches the new spot formation in each cycle, and successfully predicted the late onset of the current Cycle 24.
“We expected to see the start of the zonal flow for Cycle 25 by now,” Hill explained, “but we see no sign of it. This indicates that the start of Cycle 25 may be delayed to 2021 or 2022, or may not happen at all.”
In the second paper, Matt Penn and William Livingston see a long-term weakening trend in the strength of sunspots, and predict that by Cycle 25 magnetic fields erupting on the Sun will be so weak that few if any sunspots will be formed. Spots are formed when intense magnetic flux tubes erupt from the interior and keep cooled gas from circulating back to the interior.
For typical sunspots this magnetism has a strength of 2,500 to 3,500 gauss (Earth’s magnetic field is less than 1 gauss at the surface); the field must reach at least 1,500 gauss to form a dark spot.
Using more than 13 years of sunspot data collected at the McMath-Pierce Telescope at Kitt Peak in Arizona, Penn and Livingston observed that the average field strength declined about 50 gauss per year during Cycle 23 and now in Cycle 24.
They also observed that spot temperatures have risen exactly as expected for such changes in the magnetic field. If the trend continues, the field strength will drop below the 1,500 gauss threshold and spots will largely disappear as the magnetic field is no longer strong enough to overcome convective forces on the solar surface.
Moving outward, Richard Altrock, manager of the Air Force’s coronal research program at NSO’s Sunspot, NM, facilities has observed a slowing of the “rush to the poles,” the rapid poleward march of magnetic activity observed in the Sun’s faint corona. Altrock used four decades of observations with NSO’s 40-cm (16-inch) coronagraphic telescope at Sunspot.
“A key thing to understand is that those wonderful, delicate coronal features are actually powerful, robust magnetic structures rooted in the interior of the Sun,” Altrock explained. “Changes we see in the corona reflect changes deep inside the Sun.”
Altrock used a photometer to map iron heated to 2 million degrees C (3.6 million F). Stripped of half of its electrons, it is easily concentrated by magnetism rising from the Sun. In a well-known pattern, new solar activity emerges first at about 70 degrees latitude at the start of a cycle, then towards the equator as the cycle ages. At the same time, the new magnetic fields push remnants of the older cycle as far as 85 degrees poleward.
“In cycles 21 through 23, solar maximum occurred when this rush appeared at an average latitude of 76 degrees,” Altrock said.
“Cycle 24 started out late and slow and may not be strong enough to create a rush to the poles, indicating we’ll see a very weak solar maximum in 2013, if at all. If the rush to the poles fails to complete, this creates a tremendous dilemma for the theorists, as it would mean that Cycle 23’s magnetic field will not completely disappear from the polar regions (the rush to the poles accomplishes this feat). No one knows what the Sun will do in that case.”
All three of these lines of research to point to the familiar sunspot cycle shutting down for a while. “If we are right,” Hill concluded, “this could be the last solar maximum we’ll see for a few decades. That would affect everything from space exploration to Earth’s climate.”
That last may be the understatement of the century!!!
A photo of a sunspot taken in May 2010, with Earth shown to scale.This image with 0.1 arcsecond resolution from the Swedish 1-m Solar Telescope represents the limit of what is currently possible in terms of spatial resolution. CREDIT: The Royal Swedish Academy of Sciences, V.M.J. Henriques (sunspot), NASA Apollo 17 (Earth)
The k2p blog 