The modulation of the emission of the combination frequencies by geomagnetic pulsations

Artificial VLF emission was generated by heating the midlatitude ionosphere with modulated emission from a powerful short-wave transmitter during the development of substorms in order to study the effect of ionospheric currents on the intensity of the artificial VLF emission. It was found that the intensity of the VLF emission is correlated with the strength of the current in the auroral electrojet. Modulations of the artificial emission were observed during geomagnetic pulsations accompanied by auroral luminosity and riometer absorption. The change in artificial VLF emission intensity is in antiphase with the pulsations measured by the photometer and riometer, so the modulation is not the result of changes in ionospheric conductivity, but may be the result of changes in electric field.