CSES observations of ELF wave radiation excited by the EISCAT heater

Modulation heating of the ionosphere using high-power high-frequency (HF) radio waves can generate an extremely low frequency (ELF) radiation source in the ionosphere, such as amplitude-modulation (AM) heating of the auroral electrojet or using two HF radio waves to illuminate the same region of the ionosphere to form beat-wave (BW) modulation. We first present observations of ELF waves received on the China seismo-electromagnetic satellite (CSES) and on the ground simultaneously, which were excited in the European Incoherent Scatter Scientific Association (EISCAT) modulation heating experiment carried out alternately in the AM and BW modes. When the CSES passed over the EISCAT heater, ELF waves excited in the AM and BW modes were received successfully by an electric field detector on board. The comparison of the received results between the satellite and the ground demonstrates that although the intensity of the ELF signals excited in the BW mode is far lower than that in the AM mode on the ground, the ratio of ELF wave intensities between the satellite and the ground in the BW mode is significantly larger than that in the AM mode. According to the experimental results, the propagation characteristics are simulated using the full-wave method when the ELF radiation sources are located in the D and F regions in the ionosphere.