On the 9^th of July, 2020, a detailed noise test was carried out in the Széchenyi István Geophysical Observatory in order to survey the electromagnetic noises generated in the very low frequency (VLF; 3-30 kHz) and extremely low frequency (ELF; 3 Hz - 3 kHz) bands by different electrical devices operating in the observatory. During a ~3 hour long period, the measurements of the observatory, the power supply of buildings as well as solar panels and charging of the batteries were shut down one-by-one and finally the main power supply from the nearby village Fertőboz was interrupted for a few minutes. A pair of induction coil magnetometers run from a battery had been installed for this test period and provided information on the changes in the ELF noise environment during the test. Although the ELF-band noise contamination in the measurements reduced in connection to the elimination of internal noise sources in the observatory, it seems that external noise sources outside the observatory are too powerful and prohibit local monitoring of the Schumann resonances in the atmospheric magnetic field. Therefore, a new location for a permanent magnetic SR station is needed.

Tamás Bozóki, József Bór, Dániel Piri, Attila Novák and Csaba Molnár (2021): ELF Noise Test in the Széchenyi István Geophysical Observatory. Geophysical Observatory Reports, 2020, 14-17. https://doi.org/10.55855/gor2020.2