ИСТИНА

We present the results of multi-station ground-based observations of low-frequency electromagnetic fields from ionospheric source initiated by powerful high frequency (HF) radio-waves emitted by EISCAT/heating facility. The HF heating modulates the electron temperature in the D-region ionosphere that leads to conductivity modulation. The auroral electrojet electric field with modulated conductivity generates a time-varying current which radiates VLF electromagnetic waves at the modulation frequency. In this work, we study the relationship between the intensity of the EISCAT-generated ELF/VLF signals and the ionospheric equivalent currents calculated from ground-based magnetometers data (IMAGE stations). The report is dealing with the results of two heating experiments carried out by AARI in October 2016 and by the China Research Institute of Radio Wave Propagation in November 2017. The components of the ELF/VLF electromagnetic field have been recorded by high-latitude stations, namely “Lovozero”, “Verkhnetulomsky” and “Lotta” at the Kola peninsula, “Kannuslehto” (Sodankylä, Finland), and also at the “Barentsburg” (Svalbard, Norway). We present some data showing that the time variations of the received ELF/VLF wave amplitudes in about 50% of all cases taken into the statistical analysis are strongly correlated with the variations of the ionospheric equivalent currents. In these cases, we also tried to reveal a relationship between the auroral electrojet dynamic and the parameters of the generated ELF/VLF waves.