Long-term observations of Schumann resonances at Modra Observatory



[1] The paper presents a summary of more than 4 years of continuous Schumann resonance (SR) monitoring of the vertical electric component at Modra Observatory. Principal parameters (peak frequency, amplitude, and quality factor) are determined for four resonances from 7 to 30 Hz, i.e., for modes one through four. Attention is also given to the less frequently compiled mode four. The resonance parameters are computed from 48 daily measurements and are represented as the mean monthly values for each time of the detection. Fitting of spectral peaks by Lorentz function is the main method used in data postprocessing. Diurnal, seasonal variations and the indication of interannual variations of these parameters (especially peak frequency) are discussed. The results are compared with other observatory measurements. Our observations confirm that variations in peak frequency of the lower-SR modes can be attributed mainly to the source-observer distance effect.