Schumann resonance and global lightning activity

Temporal variations of the global lightning activity are deduced from the long-term Schumann resonance (SR) continuous records. The intensities of the horizontal magnetic field component of the first, second, and third SR modes were monitored at the Tottori Observatory (35.5°N and 134.33°E). Variations of the effective source-observer distance were estimated from the data using the ratios between intensities of individual SR modes. This allowed us to compensate for the source motion in respect to the observatory and extract from the records the average diurnal variations of the global lightning activity itself. The procedure has been done for every month within the observation period. The results show that the estimator for the effective distances between the field-site and the global centers of the lightning activity remain very stable. Simultaneously the temporal changes of the fields monitored and of the relevant global lightning activity derived from the records demonstrate substantial variability