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  • Communications Effects of Space Weather
  • One of Space weather
  • Ionosphere and wireless

  • A century after Marconi’s feat, the ionosphere remains both a facilitator and a disturber in numerous communications applications. The military, as well as police and fire emergency agencies in many nations, continue to rely on wireless links that make extensive use of frequencies from kHz to hundreds of MHz and that use the ionosphere as a reflector. Commercial air traffic over the north polar regions continues to grow following the political changes of the late 1980s-early 1990s, and this traffic relies heavily on RF communications. Changes in the ionosphere that affect RF signal propagation can be produced by many mechanisms including direct solar photon emissions (solar UV and x-ray emissions), solar particles directly impacting polar region ionospheres, and radiation belt particles precipitated from the trapped radiation environment during geomagnetic storms.
  • At higher (few GHz) frequencies the production of “bubbles” in ionosphere densities in equatorial regions of the Earth can be a prime source of scintillations in satellite-toground signals. Engineers at the COMSAT Corporation discovered these effects after the deployment of the INTELSAT network at geosynchronous orbit [Taur, 1973]. This discovery is an excellent example of the surprises that the solar-terrestrial environment can hold for new technologies and for services that are based upon new technologies. A major applications satellite program (C/NOFS), scheduled for launch in 2006, has been designed by the U.S. Department of Defense to explicitly study the causes and evolutions of the processes that produce equatorial region bubbles, and to examine means of mitigation. Disturbed ionosphere currents during geomagnetic storms can also be the cause of considerable problems at all geomagnetic latitudes in the use of navigation signals from the Earth-orbiting Global Positioning System (GPS), which provides precise location determination on Earth. These ionosphere perturbations limit the accuracy of positional determinations, thus presently placing limits on some uses of space-based navigation techniques for applications ranging from air traffic control to ship navigation to many national security considerations. The future European Galileo Navigation Satellite System (GNSS) will also have to take into account ionosphere disturbances in order to ensure its successful operations

- Space Weather Effects on Communications -