World map of ELF/VLF emissions as observed by a low-orbiting satellite
Résumé
The worldwide distribution of ELF and VLF emissions is presented in order to gain an understanding of the relative importance of the VLF ground-based transmitters and thunderstorm activities. Data is obtained from filterbanks with the frequency range of observations extending from tens of Hz to 15 Hz. The geomagnetic as well as geographical plots of the data at different frequency are provided, the influence of VLF ground-based transmitters and thunderstorm activities are discussed, and the results are compared with a theoretical work identifying the spatial distribution of electron precipitation induced by ground-based transmitters. The geomagnetic representations indicate that the data recorded via filterbanks is low-altitude ELF hiss and VLF hiss, while the geographical plots show intense emissions over North America at all frequencies.