Relationship between median intensities of electromagnetic emissions in the VLF range and lightning activity
Abstract
We present results of a survey of VLF electromagnetic waves observed by the DEMETER spacecraft (altitude about 700 km, launched in June 2004, and still operating). The median value of the power spectral density of electric field fluctuations in the frequency range 1–10 kHz is evaluated as a function of the position of the spacecraft, frequency, magnetic local time, and season of the year.
It is shown that there are significant seasonal differences between the satellite observed wave intensities throughout the year and it is demonstrated that these are due to the lightning activity changes of the Earth. The frequency spectrum at frequencies 0–20 kHz of electromagnetic emissions caused by the lightning activity is investigated as a function of geomagnetic latitude.