Modeling the characteristics of whistlers generated from a gigantic jet (GJ) is performed as well as to examine satellite observations and find the existence of such type of whistlers. Modeling is based on disturbances in the electric field, as measured by NCKU ELF/VLF station, associated with a representative tree-like GJ event over typhoon Lionrock. The power spectrum of observed GJ differs from that of common cloud-to-ground lightning in its primary intensities below a few kHz and an initiating lightning on a wider frequency range. Therefore, the calculated frequency-time spectrogram shows two sequent whistlers, with the later one emitted mainly below a few kHz. Detectability is evaluated by considering the absorption of amplitudes resulted from particle collisions associated with the propagation of generated waves. Differences between GJ-generated signals and common lightning-generated whistlers are also explored in order to distinguish them in observational data. The electric fields observed by DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) satellite mission are investigated. Paired whistlers, detected by DEMETER in the ionosphere at time right after a tree-like GJ event observed by ISUAL (Imager of Sprites and Upper Atmospheric Lightning), occurred at the closest location to the satellites among all examined events. The power distribution features on the frequency-time spectrogram are found to resembling the modeled two sequent whistlers.
Abstracts of 7th biennial VERSIM and Radiation Belt Symposia