Propagation
 

This from the RSGB:

The next sunspot cycle will be 30-50 per cent stronger than its predecessor
and will begin as much as a year later than previous forecasts, according to
scientists from the US-based National Centre for Atmospheric Research. If
the prediction is correct, the next solar maximum could be the most intense
since the historic solar maximum of 1958.

The National Centre for Atmospheric Research scientists believe they have
mastered the art of accurately forecasting solar cycles.

They have developed a computer model that they claim has simulated the
strength of the past eight solar cycles with an accuracy of more than 98%.

This amazing precision is achieved by using the subsurface movements of
sunspot remnants of the previous two solar cycles to calculate the strength
of the next cycle. Mausumi Dikpati, the leader of the research team, said:
"Our model has demonstrated the necessary skill to be used as a forecasting
tool."

The Sun undergoes 11-year cycles of activity, from peak storm activity to
quiet and back again. But until now there was no precise method of
predicting their timing and strength. Being able to accurately predict the
sun's cycles years ahead could help society prepare for periods of intense
solar storms, which can disrupt communications, slow down satellite orbits
and crash power systems.

Solar storms are thought to be caused by twisted magnetic fields in the Sun
that suddenly snap, releasing huge amounts of energy. They usually occur
near dark regions of concentrated magnetic fields known as sunspots.

(RSGB http://www.rsgb.org/news/gb2rs.htm )