Electromagnetic emissions detected in the topside ionosphere related to the human activity
Résumé
The Earth ionosphere undergoes various man-made influences. The electromagnetic emissions in the topside ionosphere have been investigated ever since first satellites were located on the orbits. Despite the fact that the analysis of properties of Earth electromagnetic environment has had a long history, the topics related to the electromagnetic pollutions are still not sufficiently reported. The development of new telecommunication technologies and the increased level of electromagnetic noises from VLF to microwave frequency range in the Earth environment should focus our investigations on that problem. The RF measurements can be used to diagnose the different electron plasma waves, the local electron densities as well as the maximum F2 layer electron densities. The HF diagnostics performed on the low orbiting satellite detected the enhancement of radiation, particularly over the Euro-Asia region. Thus over the Euro-Asia area enhancements of background radiation were detected in the whole frequency band, which is connected with natural plasma radiation, and for frequencies greater than the plasma frequency at maximum F2 layer, triggered by artificial ground-based origin noises. Electromagnetic waves permanently pumped to the ionosphere by the system of broadcasting stations can disturb the nearest space environment. The observed broadband emissions are a superposition of natural plasma emissions and man-made noises. The aim of this paper is to discuss the morphological properties and origins of the observed HF and VLF wave activity generated by human activity, detected at the low orbiting satellite CORONAS- I and AUREOL-3.