Interrelation between ELF transients and ionospheric disturbances in association with sprites and elves

Red sprites and elves were observed in Japan during the winter of 1998/99 i n Hokuriku region by the group of Tohoku Univ. [Fukunishi et al., EOS, 80(4 6), F217, 1999]. We analyze quantitatively the results from coordinated mea surement consisting of ELF transients, VLF subionopheric disturbances and l ightning discharges associated with the optical events. We find the clear s traightforward relationship between charge transfer of the parent discharge calculated from ELF (f<15 Hz) and the ionospheric disturbances regardless of the types of optical events indicating significant atmosphere-mesosphere -ionosphere coupling. Sprites tend to associate with a large ionospheric di sturbance (-13<similar to>+4.6 dB) with a large charge transfer (52 similar to 175 C), whereas a large lightning peak current (+223 similar to +470 kA ) (or slow-tail amplitude) leading to the strong EMP is necessary to initia te elves, but with rather small ionospheric disturbances.