Comments on the proton whistler generation process

Extremely low frequency plasma turbulence recorded by the DEMETER satellite in the ionosphere over the Abruzzi region prior to the April 6, 2009, L’Aquila earthquake

“…As usual at lower frequencies, the proton whistlers have a frequency band that is limited by the proton gyrofrequency (given by a model of the Earth magnetic field), and they have opposite polarization, as it is seen in Figure 8. Proton whistlers are usually generated by the same lightning strikes as the electron whistlers [Stefant 1985], although for this event, the most powerful electron whistlers are not associated with the most powerful proton whistlers, as can be seen in the next two panels of Figure 8. The changes in the atmospheric electric field during the preparation phase of the earthquake can be a source of similar emissions.…”

On remote sensing of transient luminous events' parent lightning discharges by ELF/VLF wave measurements on board a satellite

“…According to its power density, it would be surprising that sprite-produced ELF bursts, generated at the sprite altitude, and observed at ground, would be visible on the DEMETER ELF spectrogram. The most intense proton whistlers, produced by the ELF part of the first 0+ whistler, present two very scarce characteristics according to Stefant [1985]: (1) there is no frequency gap between f cr and f H + (generally the gap extends slightly above f H + ) on the ''electron whistler'' part, and (2) the ''electron whistler,'' which is observed here on the magnetic as well as the electric components (the magnetic component is shown in Figure 5), is electromagnetic over the entire frequency band even around f H + . This strongly suggests that there are clearly one electron and one proton mode without unknown energy transfers between f cr and f H + .…”