|“||can adversely affect radio signals that propagate through the upper atmosphere, disrupting communication, navigation, and surveillance capabilities over wide areas on timescales ranging from minutes to hours. These disturbances can be caused directly by solar flares or indirectly by interactions between the solar wind and the Earth's magnetic field. Solar flares primarily affect the dayside of the Earth, while solar wind can affect both the dayside and nightside.||”|
High-frequency radio signals, which are used for airline, maritime, and emergency communications, are particularly susceptible to ionospheric disturbances. Effects of ionospheric disturbances can limit or restrict polar-route flights by commercial and military aircraft for several days and block amateur radio communications that are often used as a backup in disaster situations. Ionospheric disturbances induced by space-weather events can also produce signal errors in position, navigation, and timing (PNT) systems such as the Global Positioning System (GPS).