The sun’s seasonal changes aren’t like Earth’s, but they do have an impact on us. A new study, led by the National Center for Atmospheric Research (NCAR), finds the sun’s activity rises and falls over a nearly two-year period.
What kind of activity?
According to researchers, the seasonal variations come from changes in the bands of strong magnetic fields in each solar hemisphere. This won’t make August cooler, but it does affect the strength of solar storms.
“What we’re looking at here is a massive driver of solar storms,” said Scott McIntosh, lead author of the new study and director of NCAR’s High Altitude Observatory. “By better understanding how these activity bands form in the Sun and cause seasonal instabilities, there’s the potential to greatly improve forecasts of space weather events.”
The rotation of the Sun’s core affects the bands of strong magnetic fields. As these bands shift to the northern and southern hemispheres, its activity rises to a peak for about 11 months before weakening.
McIntosh compares the sun’s seasonal changes to regions on Earth that have a rainy and dry season.
The researchers say these shifting bands of magnetic fields are just as potent as 11-year sunspot cycle.
“Much like Earth’s jet stream, whose warps and waves have had severe impact on our regional weather patterns in the past couple of winters, the bands on the Sun have very slow-moving waves that can expand and warp it too,” said co-author Robert Leamon, a scientist at Montana State University. “Sometimes this results in magnetic fields leaking from one band to the other. In other cases, the warp drags magnetic fields from deep in the solar interior, near the tachocline, and pushes them toward the surface.”
According to NCAR, “The surges of magnetic fuel from the Sun’s interior catastrophically destabilize the corona, the Sun’s outermost atmosphere. They are the driving force behind the most destructive solar storms.”
McIntosh says these surges make up “over 95 percent of the large flares and CMEs.”
How this research can help predict solar activity.
Besides Earth, the Sun is one of most studied objects in our solar system. This research combined with the telescopes already looking at the sun could make forecasting solar storms even more accurate.
“Understanding the formation, interaction and instability of these activity bands will considerably improve forecast capability in space weather and solar activity over a range of timescales,” the authors wrote in the study’s abstract.
If a solar flare erupted during the ‘stormy phase,’ officials could put out a warning of a potentially stronger than normal solar storm. And, vice versa during the quiet phase in each hemisphere.