The Ultra Low Frequency (ULF) is the
frequency range between 300
hertz and 3 kilohertz. Many types of waves in the ULF frequency band can be observed in the
magnetosphere and on the ground. These waves represent important physical processes in the near-Earth plasma environment. The speed of the ULF waves is often associated with the
Alfven velocity that depends on the ambient magnetic field and plasma mass density.
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