Next Solar Cycle to be Later but More Intense, New Research Suggests

NEWINGTON, CT, Mar 7, 2006–The next solar cycle, Cycle 24, will be a year or so late in arriving but will be far more intense than the current cycle now winding down–perhaps as much as 50 percent stronger. That’s according to a new computer model unveiled March 6 by scientists at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. The researchers developed the first “solar climate” forecast using a combination of groundbreaking observations of the sun’s interior from space and computer simulation. Key to predicting the solar activity cycle is an understanding of plasma flows in the sun’s interior.

“We understood these flows in a general way, but the details were unclear, so we could not use them to make predictions before,” said NCAR’s Mausumi Dikpati, who published a paper on her research March 3 in the online edition of Geophysical Review Letters. Magnetic fields are “frozen” into the solar plasma, so plasma currents within the sun transport, concentrate and help dissipate solar magnetic fields, Dikpati explained. She said the new application utilizes innovations in direct study of the sun’s interior as well as historical data on which previous forecasts have depended.

The new technique of “helioseismology” allows researchers to see inside the sun. Helioseismology traces sound waves reverberating inside the sun to build up a picture of the interior, similar to the way ultrasound technology can create a picture of an unborn baby. The new model, known as the Predictive Flux-transport Dynamo Model, has simulated the strength of the past eight solar cycles extending back to the early 1900s with 98 percent accuracy.

If proved correct the forecast offers a sort of bad news/good news scenario for Amateur Radio operators, but not all solar scientists agree with the newest prediction. NASA solar physicist David Hathaway has declared that Cycle 23’s solar minimum already has arrived. Nonetheless, Hathaway, who was not involved in the Dikpati study, says he is excited about the new model.

“It’s based on sound physical principals, and it finally answers the 150-year-old question of what causes the 11-year sunspot cycle,” Hathaway said.

Hathaway says his own research concurs that Cycle 24 will be more intense than Cycle 23. However, he predicts the next solar cycle will begin late this year or early next year rather than a year later. He points out that historical data suggest that the more powerful cycles begin earlier rather than later.

Under the model developed by Dikpati and her colleagues, the poor HF propagation of Cycle 23’s terminal stages won’t reverse course until late 2007 or early 2008, and Cycle 24 won’t peak until 2012. But higher intensity normally means more and longer HF band openings–with the exception of solar storms. As the sunspot cycle bottoms out, however, conditions can be more favorable for VHF and UHF operation.

For public utilities and satellite operators, the new model’s prediction regarding solar storms is mostly bad news. Depending on their intensity, solar eruptions–with their powerful releases of radiation–can disrupt power grids on Earth and satellite operations in space, including communications links and GPS. Previous forecasts for Cycle 24 had suggested a significantly milder intensity.

A next step for the NCAR researchers will be to develop an advanced model that can give advance warning of individual solar storms, says Richard Behnke of the National Science Foundation. NASA’s Living With a Star program and the National Science Foundation funded the research.–information from NASA, NCAR and news reports was used in developing this report

Acknowledgement: ARRL thanks Bill Sexton, N1IN, for his assistance in editing this article.