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Keywords:

  • Schumann resonances;
  • electric fields;
  • ionosphere;
  • radiowave propagation

Lightning flashes can generate electromagnetic waves in the atmosphere. When these waves have a particular frequency, they can resonate in the cavity formed by the Earth's surface and the bottom of the ionosphere. This phenomenon, known as a Schumann resonance, has been observed from the ground and been used to study a variety of atmospheric properties. Now Simões et al. report the first observations of Schumann resonances from a satellite. They detected the extremely low frequency waves with the Communications/Navigation Outage Forecasting System (C/NOFS) satellite, which studies ionospheric conditions. The researchers suggest that because these waves were detected in the ionosphere, outside of the surface-ionosphere cavity, some of them are unexpectedly leaking out into space. Therefore scientists may need to revise models of extremely low frequency wave propagation in the ionosphere. (Geophysical Research Letters, doi:10.1029/2011GL049668, 2011)