Solar cycle The sun’s 11 year heartbeat explained
Solar activity is predicted to fall 60% in 2030s, to ‘mini ice age’ levels, according a new study
Irregular heartbeat of the Sun driven by double dynamo
- July 9, 2015
- Royal Astronomical Society (RAS)
- Summary: Irregular heartbeat of the Sun driven by double dynamo
- A new model of the Sun’s solar cycle is producing unprecedentedly accurate predictions of irregularities within the Sun’s 11-year heartbeat. The model draws on dynamo effects in two layers of the Sun, one close to the surface and one deep within its convection zone. Predictions from the model suggest that solar activity will fall by 60 per cent during the 2030s to conditions last seen during the ‘mini ice age‘ that began in 1645.
It is 172 years since a scientist first spotted that the Sun’s activity varies over a cycle lasting around 10 to 12 years. But every cycle is a little different and none of the models of causes to date have fully explained fluctuations. Many solar physicists have put the cause of the solar cycle down to a dynamo caused by convecting fluid deep within the Sun. Now, Zharkova and her colleagues have found that adding a second dynamo, close to the surface, completes the picture with surprising accuracy.
“We found magnetic wave components appearing in pairs, originating in two different layers in the Sun’s interior. They both have a frequency of approximately 11 years, although this frequency is slightly different, and they are offset in time. Over the cycle, the waves fluctuate between the northern and southern hemispheres of the Sun. Combining both waves together and comparing to real data for the current solar cycle, we found that our predictions showed an accuracy of 97%,” said Zharkova.
Zharkova and her colleagues derived their model using a technique called ‘principal component analysis’ of the magnetic field observations from the Wilcox Solar Observatory in California. They examined three solar cycles-worth of magnetic field activity, covering the period from 1976-2008. In addition, they compared their predictions to average sunspot numbers, another strong marker of solar activity. All the predictions and observations were closely matched.
Looking ahead to the next solar cycles, the model predicts that the pair of waves become increasingly offset during Cycle 25, which peaks in 2022. During Cycle 26, which covers the decade from 2030-2040, the two waves will become exactly out of synch and this will cause a significant reduction in solar activity.
“In cycle 26, the two waves exactly mirror each other – peaking at the same time but in opposite hemispheres of the Sun. Their interaction will be disruptive, or they will nearly cancel each other.
We predict that this will lead to the properties of a ‘Maunder minimum’,” said Zharkova. “Effectively, when the waves are approximately in phase, they can show strong interaction, or resonance, and we have strong solar activity. When they are out of phase, we have solar minimums. When there is full phase separation, we have the conditions last seen during the Maunder Minimum, 370 years ago.”
The Solar Cycle: The sun’s 11 year heartbeat
Extensive recording of solar sunspot activity began in 1755
Conventional wisdom holds that solar activity swings back and forth like a simple pendulum.
At one end of the cycle, there is a quiet time with few sunspots and flares.
At the other end, solar max brings high sunspot numbers and frequent solar storms.
It’s a regular rhythm that repeats every 11 years.
Reality is more complicated.
Astronomers have been counting sunspots for centuries, and they have seen that the solar cycle is not perfectly regular.
Eleven years in the life of the Sun, spanning most of the solar cycle (Solar cycle 23 in this image), as it progressed from solar minimum to maximum conditions and back to minimum (upper right) again, seen as a collage of ten full-disk images of the lower corona. Of note is the prevalence of activity and the relatively few years when our Sun might be described as “quiet.” Credit: ESA&NASA/SoHO source
The solar dynamo is the physical process that generates the Sun‘s magnetic field. The Sun is permeated by an overall dipole magnetic field, as are many other celestial bodies such as the Earth. A helical dynamo deep near the center of the Sun’s mass produces a strong electric current flowing deep within the star, following Ampère’s law. A second chaotic dynamo near the surface of the Sun is responsible for weaker fluctations in the Sun’s magnetic field which often result in the most noticeable solar activity. These currents of electrical conduction are produced by shear between different parts of the Sun that rotate at different rates, governed by the laws of magnetohydrodynamics
The Maunder Minimum
The Maunder Minimum (also known as the prolonged sunspot minimum or Solar minimum) is the name used for the period starting in about 1645 and continuing to about 1715 when sunspots became exceedingly rare, as noted by solar observers of the time. It caused London’s River Thames to freeze over, and ‘frost fairs‘ became popular. Examples of very cold winters are 1683-4, 1694-5, and the winter of 1708–9. In such years, River Thames frost fairs were held.
This period of solar inactivity also corresponds to a climatic period called the ‘ Little Ice Age‘ when rivers that are normally ice-free froze and snow fields remained year-round at lower altitudes.
There is evidence that the Sun has had similar periods of inactivity in the more distant past, Nasa says.
The connection between solar activity and terrestrial climate is an area of on-going research.
Some scientists hypothesize that the dense wood used in Stradivarius instruments was caused by slow tree growth during the cooler period.
Instrument maker Antonio Stradivari was born a year before the start of the Maunder Minimum.
Whitehouse, David (December 17, 2003)."Stradivarius 'sound' due to Sun". BBC News.
What is a solar cycle
Solar Cycle Predictions
List of Solar Cycles
The Sunspot Cycle
IPS – Solar Conditions – Monthly Sunspot Numbers
Layers of the sun
Principal Component Analysis
Principal Component Analysis explained visually
Solar Influences Data Analysis Center (SIDC)
Solar Cycle Progression
Graphics of historic solar cycles at the SIDC page
Near realtime solar images from SOHO
Global Temperature Trends From 2500 B.C. To 2040 A.D.
First Ever STEREO Images of the Entire Sun (Feb 6, 2011)
Graphs of Historical Solar Cycles
IRIS (Interface Region Imaging Spectrograph)
History of The Great Freeze of ’63 Windsor History
Ultimate History – The Frost Fairs of London
Frostiana or a history of the River Thames in a frozen state (PDF) Feb 5 1814
- Royal Astronomical Society (RAS)
- Irregular heartbeat of the Sun driven by double dynamo
- Switching to the new Sunspot Number on July 1, 2015: a challenging transition
- Deep solar minimum and global climate changes – Journal of Advanced Research Volume 4, Issue 3, May 2013, Pages 209–214. Special Issue on “Heliospheric Physics during and after a deep solar minimum” — Selected papers from the IAGA-III International Symposium, Luxor, Egypt, 13 – 17 November 2011
- Kane, R.P. (2002). “Some Implications Using the Group Sunspot Number Reconstruction“. Solar Physics 205(2), 383-401.
- Giampapa, Mark S; Hill, Frank; Norton, Aimee A; Pevtsov, Alexei A. “Causes of Solar Activity” (PDF). A Science White Paper for the Heliophysics 2010 Decadal Survey
- Modeling of the solar activity double cycle using dynamical systems E. P. Popova, K. A. Potemina Geomagnetism and Aeronomy December 2013, Volume 53, Issue 8, pp 941-944. Date: 11 Dec 2013
- Charbonneau, P. (2014). “Solar Dynamo Theory”. Annual Review of Astronomy and Astrophysics 52: 251. doi:10.1146/annurev-astro-081913-040012.
- The Astrophysical Journal Letters, 720:L20–L25, 2010 September 1 doi:10.1088/2041-8205/720/1/L20 C 2010. The American Astronomical Society. All rights reserved. Printed in the U.S.A. A DOUBLE-RING ALGORITHM FOR MODELING SOLAR ACTIVE REGIONS: UNIFYING KINEMATIC DYNAMO MODELS AND SURFACE FLUX-TRANSPORT SIMULATIONS (PDF)
- Sudden transitions and grand variations in the solar dynamo, past and future. http://dx.doi.org/10.1051/swsc/2012008 – 25 June 2012
- Regional climate impacts of a possible future grand solar minimum Nature Communications 6, Article number: 7535 doi:10.1038/ncomms8535 , 23 june 2015
Articles in the news
The Sun may be headed for a little quiet time Phil Plait | Slade.com June 14 2011
Are we headed for a new ice age? Climatologist: 30-Year Cold Spell Strikes Earth – Sunday, 16 Nov 2014
Here are the countries most likely to survive climate change ScieneAlert.com 15 Jan 2015
Solar activity predicted to fall 60% in 2030s, to ‘mini ice age’ levels: Sun driven by double dynamo – ScienceDaily 9 July 2015
Is a mini ICE AGE on the way? Scientists warn the sun will ‘go to sleep’ in 2030 and could cause temperatures to plummet – DailyMail 10 July 2015
No, We’re Not Headed for a Mini–Ice Age Phil Plait | Slade.com JULY 14 2015