Efficient three-source model for Schumann resonance

Abstract

An efficient and simple model of global thunderstorm activity is described, which allows computing the diurnal and seasonal variations of the peak frequency of the first Schumann resonance (SR) mode. The model results are compared with the long-term monitoring of the diurnal - seasonal variations of the first SR frequency recorded in the vertical electric field component. The records were performed at the Hungarian Széchenyi István Geophysical Observatory or the Nagycenk Geophysical observatory (NCK; 47.6°N, 16.7°E). They cover the 16-year period ranging from Jan. 1994 to Dec. 2009. Comparison of model data with experimental observations allowed formulating the following conclusions. The model of the global thunderstorm activity is rather simple, it suggests that position of the global thunderstorm centers in Asia, Africa, and America varies from month to month, but it recurs from year to year. The only exception in spatial parameters is the effective width of the area occupied by lightning strokes, which is found from the observational data. Diurnal variations in thunderstorm intensity correspond to classical WMO data. In spite of its simplicity, the model is quite efficient; it allows accurately compute the diurnal variations of the first mode peak frequency. Deviations of the model f₁ values from those observed experimentally do not exceed 1% while the cross-correlation coefficient of their temporal variations is equal to 0.5–0.6. Authors hope to apply this model in future studies, as well as in interpreting observations at other field sites. Extension of comparable data will clarify the effective parameters of the global thunderstorm activity serving as the source of SR oscillations.