ELF Electromagnetic Waves and Ionospheric Physics SeminarSeptember 24, 2025József Bór (HUN-REN EPSS): "Studying electromagnetic seasons using an almost 22 years-long time series of Schumann resonance frequencies (presented on IAGA2025) Abstract: The seasons are yearly recurring time periods of the year where the days exhibit broadly similar characteristics (e.g., the mean temperature for meteorological seasons). Also being linked to the latitude of the Sun, characteristic variations of atmospheric electricity parameters can be used to define electromagnetic (EM) seasons. It is well documented that the daily frequency pattern (DFP) of the Schumann resonance (SR) modes provide a solid basis for this approach. In this study, we used the time series of the 1st and 2nd mode DFP correlations from the years 1994-2016 to revisit the methods for determining the length of the EM seasons, the changing of their lengths over the covered time period, and the consistency of the results obtained from the two considered SR modes. We analyzed the vertical electric component of the atmospheric EM field from NCK (47.63° N, 16.42° E), a midlatitude SR monitoring station in Europe. It was found that the position and the length of the EM seasons within the year depend on the applied analysis method and (slightly) on the SR mode selected for the evaluation, too. We suggest a method that can be applied to SR data recorded at a station of any latitude. Nevertheless, the preferred location of a SR station is discussed in this aspect. The results clearly show that the January-like main EM season is the longest one. The consistent (albeit insignificant) trend in its length suggests that this season has been lengthening in the past 2-3 decades. Duration: ~ 30 minutes Contact: Contact_ELFseminar(at)oa.uj.edu.pl |