Convective ionospheric storms: a major space weather problem

Abstract

Some 50 years into the space age, technical societies are deeply committed to the utilization of space. For the military, space is the ultimate high ground from which a variety of surveillance, communications, and navigation systems operate. For industry, the communications and positional/navigational opportunities using space-based systems are virtually unlimited. However, when the plasma between the satellite and the receiver is turbulent, satellite signals scintillate in a manner analogous to the twinkling of starlight as it traverses the turbulent atmosphere, and both communication and navigation systems can be seriously affected. With the rapidly developing use of space assets comes the realization that ionospheric plasma, through which communications and navigation signals must pass, is not a benign medium. The most severe ionospheric weather occurs within +/-20° of the geomagnetic equator where stored gravitational energy sometimes is released after sunset, depending on the condition of the equatorial ionosphere, to form vast plumes of turbulent plasma. The plumes rise quickly in a manner analogous to thunderstorm convection and, due to their electrical properties, are transmitted rapidly for vast distances north and south along the Earth's magnetic field. Termed convective ionospheric storms (CIS), to emphasize the analogy of the ionospheric process to thunderstorms, these plumes are caught up in the high-speed eastward plasma drift and often last until well after midnight. As a result, a single storm can affect a very large area in its lifetime. To fully understand the problems posed by CIS, a detailed explanation of what is currently known about this topic is provided here, along with the methods for CIS monitoring. Weaknesses in scientific theory and monitoring capacities are also discussed.