A new study has found that just like the Earth, our Sun experiences seasonal changes which scientists believe can now help them better predict solar storms.
The Sun goes through a type of seasonal variability with its activing waxing and waning over the course of almost two years, according to the study published in Nature Communication and conducted by a team of researchers led by the National Centre for Atmospheric Research.
This behavior affects the peaks and valleys of the approximately 11 year solar cycle and can amplify or weaken the solar storms that impact Earth's atmosphere.
The quasi-annual variations appear to be driven by changes in the bands of strong magnetic fields in each solar hemisphere. These bands help shape the approximately 11 year cycle and are actually part of a longer cycle that lasts about 22 years.
The overlapping bands are fueled by the rotation of the Sun's deep interior. As the bands move with the Sun's northern and southern hemispheres, activity raises to a peak over a period of 11 years and then begins to wane.
"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."
Understanding these new cycles can help lead to better predictions of massive geomagnetic storms in the Earth's outer atmosphere that can disrupt satellite operations, interrupt communications grids, disrupt power grids and other technologies.
"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."
The surges of magnetic fuel from the Sun's interior drastically destabilize the Sun's outermost atmosphere, the corona, and are the driving force behind the most destructive solar storms.
The quasi-annul variations can be likened to regions of the Earth that experience two distinct seasons, such as the rainy season and the dry season, McIntosh said.
"If you understand what the patterns of solar activity are telling you, you'll know whether we're in the stormy phase or the quiet phase in each hemisphere," McIntosh said. "If we can combine these pieces of information, forecast skill goes through the roof."
