It has been 172 years since scientists first discovered the Sun’s activity varied over a cycle of 10 to 12 years. But they noticed that every cycle was just a little bit different, and for a long time, they had no clues to explain the fluctuations.
Solar scientists attributed the fluctuations to a dynamo of convecting fluids, deep within the Sun. But now, Professor Valentina Zharkova, of the University of Northumbria and her colleagues have added a second dynamo to the equation, one that is closer to the Sun’s surface, completing the picture with great accuracy.
Studying magnetic waves and solar activity leads to prediction
Zharkova says they found magnetic wave components appear in pairs, originating in two different layers in the Sun’s interior. Both of these magnetic waves have a frequency of about 11 years. But they are “slightly different, and they are offset by time,” she says.
The team created a model using a technique called “principal component analysis” of magnetic field observations using data derived from the Wilcox Solar Observatory in California. Three solar cycles worth of magnetic field activity was studied, covering a period from 1976 to 2008. They also used average sunspot numbers and activity in calculating their predictions and observations.
Over the cycle, the magnetic waves fluctuate between the northern and southern hemispheres of the Sun. Figuring this out, Zharkova and her colleagues combined both waves and then compared them to “real data from the current solar cycle.” Surprisingly, the team’s predictions showed an accuracy of 97 percent. Researchers, using this data are now able to anticipate the Sun’s activity, and this has led Zharkova to make an astounding prediction.
Predicting the little ice age, or “Maunder Minimum” between 2030 and 2040
Zharkova’s model shows them the two magnetic waves will become increasingly offset in cycle 25, which peaks in 2022. In cycle 26, covering the decade 2030 to 2040, the two magnetic waves will be exactly out of synch, and this will cause a 60 percent 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.
During this period called the Maunder Minimum, very few sunspots will be seen on the Sun’s surface and the overall brightness of the Sun will be slightly decreased. The Sun basically enters a quiet phase. The Maunder Minimum was the name given to the little ice age that occurred between 1650 and 1710. During that time, North America and Europe experienced very cold winters.
In England, it was so cold, the River Thames froze, Alpine glaciers crept into farmlands and in the Netherlands, the canals froze over, an event rarely seen today. From what Dr. Zharkova says, it will depend on how far the magnetic waves become separated. She says, ” 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 study was been published in the journal Royal Astronomical Society on July 9, 2015, under the title: “Irregular heartbeat of the Sun driven by double dynamo”
This study was also presented at the Royal Astronomical Society’s National Astronomy Meeting 2015 in Llandudno, Wales.
