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  • Communications Effects of Space Weather
  • One of Space weather
  • Ionosphere and Earth currents

  • The basic physical chain of events behind the production of large potential differences across the Earth’s surfacebegins with greatly increased electrical currents flowing in the magnetosphere and the ionosphere. The temporal and spatial variations of these increased currents then cause large variations in the time rate of change of the magnetic field as seen at Earth’s surface. The time variations in the field in turn induce potential differences across large areas of the surface that are spanned by cable communications systems (or any other systems that are grounded to Earth, such as power grids and pipelines). Telecommunications cable systems use the Earth itself as a ground return for their circuits, and these cables thus provide highly conducting paths for concentrating the electrical currents that flow between these newly established, but temporary, Earth “batteries”. The precise effects of these “anomalous” electrical currents depend upon the technical system to which the long conductors are connected. In the case of long telecommunications lines, the Earth potentials can cause overruns of the compensating voltage swings that are designed into the power supplies [e.g., Anderson et al., 1974] that are used to power the signal repeaters and regenerators (the latter in the case of optical transmissions). Major issues can arise in understanding in detail the effects of enhanced space-induced ground electrical currents on cable systems. At present, the time variations and spatial dependencies of these currents are not well understood or predicable from one geomagnetic storm to the next. This is of considerable importance since the induced Earth potentials are very much dependent upon the conductivity structure of the Earth underlying the affected ionosphere regions. Similar electrical current variations in the space/ionosphere environment can produce vastly different Earth potential drops depending upon the nature and orientation of underground Earth conductivity structures in relationship to the variable overhead currents. Modeling of these effects is becoming advanced in many cases. This is an area of research that involves a close interplay between space plasma geophysics and solid Earth geophysics, and is one that is not often addressed collaboratively by these two very distinct research communities (except by the somewhat limited group of researchers who pursue electromagnetic investigations of the Earth).

- Space Weather Effects on Communications -