DEMETER observations of ELF waves injected with the HAARP HF transmitter

Modulated HF heating of the auroral electrojet is used to inject ELF signals into the magnetosphere that are observed on the low altitude DEMETER spacecraft. The HF heater is a component of the High‐Frequency Active Auroral Research Program (HAARP) facility in Gakona, Alaska, (located at L ∼ 4.9). Simultaneous observations of all six components of the ELF electromagnetic fields on the DEMETER spacecraft are used to estimate the total ELF power radiated downward into the Earth‐ionosphere waveguide. ELF signals generated by the HAARP heater are also simultaneously observed at a nearby ground‐based site, allowing a comparison of the ELF power in the Earth‐ionosphere waveguide versus that detected on DEMETER. The estimated values of power onboard DEMETER at different frequencies range from 0.32W to 4W, while the values of power estimated from a ground receiver at a distance of 36 km from HAARP range from 2.71W to 4.22W.