Powerful solar explosions, such as flares and coronal mass ejections, greatly disturb the electromagnetic environment around the Earth and the atmosphere. They may even impact various social systems—communications, positioning, electric power supply, aviation and activities in space. Such variations in the space environment, which can influence human activities, are called “space weather.” The space weather disaster caused by a solar explosion is a potential risk in modern society. To reduce and mitigate space weather impacts, it is essential to understand the structure and dynamics of...