Universal and local time components in Schumann resonance intensity
Abstract. We extend the technique suggested by Sentman and Fraser (1991) and discussed by Pechony and Price (2006), the technique for separating the local and universal time variations in the Schumann resonance intensity. Initially, we simulate the resonance oscillations in a uniform Earth-ionosphere cavity with the distribution of lightning strokes based on the OTD satellite data. Different field components were used in the Dayside source model for the Moshiri (Japan, geographic coordinates: 44.365° N, 142.24° E) and Lehta (Karelia, Russia, 64.427° N, 33.974° E) observatories. We use the extended Fourier series for obtaining the modulating functions. Simulations show that the algorithm evaluates the impact of the source proximity in the resonance intensity. Our major goal was in estimating the universal alteration factors, which reflect changes in the global thunderstorm activity. It was achieved by compensating the local factors present in the initial data. The technique is introduced with the model Schumann resonance data and afterwards we use the long-term experimental records at the above sites for obtaining the diurnal/monthly variations of the global thunderstorms.