THE GEOMAGNETIC STORM ON NOVEMBER 3-4, 2021: SPECTRAL CHARACTERISTICS IN ULF RANGE AT MID LATITUDES

The geomagnetic storm class G3 was recorded on November 3–4, 2021 on the ground-based magnetometers. Using time series of the data corresponding to the horizontal geomagnetic component, the spectral characteristics in the ULF range for the data collected at Panagjurishte (Bulgaria) and Conrad (Austria) observatories are obtained. To obtain the degree of correlation between the X and the Y components at both stations the coherence analysis is used. It was found that the X components have a very high degree of correlation for the entire studied period in the frequency range 0.03125–16 mHz and are fully synchronous in phase. The Y components have significant differences in phase and values of coherence for different frequency ranges. The dynamic spectra depict similar behavior along the X and Y components during the storm. The geomagnetic variations at both observatories were affected at different time scales. The main difference is that the spectral characteristics appear on time scales 200–400s, where disturbances appear simultaneously along the X component at Panagjurishte and along the Y component at Conrad.