Space Weather

Space weather, influenced by the solar wind, depends on factors like wind speed, magnetic fluctuations, and particle types. Studies highlight that the properties of the solar wind—such as helium content and how wave-like it is (Alfvénicity)—can help trace its solar origins. For example, slow solar wind that still shows high Alfvénicity may actually come from regions typically associated with fast wind. This blurs traditional categories and may help improve models of how solar wind conditions evolve and affect Earth.

Schematic for mapping in situ solar wind observations to their source regions. — A schematic for using the helium abundance and the normalized cross helicity (a magnetohydrogynamic (MHD) turbulence parameter) to identify the solar source of a solar wind observation. The green region indicates solar wind from regions with magnetic fields that only open to interplanetary space. This solar wind is helium poor and independent of the solar wind's turbulent state. The red region on the right is from regions like coronal holes that are always open to interplanetary space. This solar wind is helium-rich solar wind with fluctuations that are typically associated with Alfvén waves, the prototypical wave in a magnetized plasma. The red region on the top is from interplanetary coronal mass ejections (ICMEs). The yellow region in the middle indicates indicates a narrow range of speeds (20 km/s wide) that has an ambiguous source. The arrow indicates that the magnetic field of the source region is more likely to be continuously open to interplanetary space. From Alterman & D'Amicis (2025), arXiv e-prints.