The Seasons of Space Weather: The Quasi-Annual Forcing of The Sun's Eruptive, Radiative, and Particulate Output

The eruptive, radiative, and particulate output of the Sun are modulated by our star's enigmatic 11-year sunspot cycle. Recent work has demonstrated that the sunspot cycle is a direct result of the interaction between the overlapping activity bands of the (fundamental) 22-year magnetic activity cycle. Those activity bands are driven by the rotation of the Sun's deep interior and sunspots are just one signature of its influence on the convective atmosphere above. We present observations of shorter timescale evolution of the rotating convective system whose propagating disturbances quasi-periodically affect the magnetism of the Sun's outer atmosphere. The induced changes in surface magnetism force a strong variability in the number of flares and coronal mass ejections along with the radiative and particulate environment of the heliosphere. Understanding the root cause of the system's short-term variability will undoubtedly improve our ability to forecast and mitigate the effects of “space weather.”