Lightning discharges in association with mesospheric optical phenomena in Japan and their effect on the lower ionosphere

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A quantitative and statistical analysis was performed using data from coordinated measurements consisting of ELF waves, VLF subionospheric disturbances and lightning discharges associated with transient luminous events(TLEs). These TLEs(sprites and elves) were observed during winter lightning storms over the Sea of Japan in the winter of 1998/99. A clear, straightforward relationship was found between the charge moment of the parent discharge, calculated from ELF(f<15Hz) transients, and the ionospheric disturbances, with a correlation coefficient of 0.97 independent of the type of TLEs; this suggests significant atmosphere-mesosphere-ionosphere coupling and implies that a large quasi-electrostatic(QE) field change occurring above lightning discharges with TLEs plays a significant role in modifying the electrical properties of the lower ionosphere. Sprites tend to be associated with large ionospheric disturbancs(-13〜+ 4.6dB, compared with the unperturbed waves) and a large charge moment(260-875Ckm), whereas a relatively large lightning peak current(+223〜+ 470kA,)(or a slow-tail amplitude) leading to a strong electromagnetic pulse(EMP) but with a rather small ionospheric disturbances seems to be necessary to initiate elves.
国立極地研究所の論文