Long-term periodical variations in global lightning activity deduced from the Schumann resonance monitoring

We deduce temporal variations of the level of global lightning activity fro m the long-term Schumann resonance (SR) monitoring performed at the Tottori observatory (35.5 degrees N, 134.33 degrees E). The continuous analog reco rds of the horizontal magnetic field cover the period from August 1967 to N ovember 1970. The data show that temporal changes of the SR amplitudes vary considerably from day to day. Meanwhile, the regular diurnal and longer-sc ale variations appear after averaging. We found annual, and semiannual comp onents in variations of global thunderstorm activity between 1967 and 1970. Comparison with the long-term SR records made recently in Europe allows us to demonstrate the similarity and stability of the global thunderstorm var iations on a seasonal scale. Simultaneously, it revealed a contribution fro m winter thunderstorms in the Japan Sea to the Tottori SR records.