Abstract:
The geomagnetic disturbances caused by the geomagnetic storm on 12 October 2021 – class G1 increasing to G2 are investigated. The data set, recorded at 1s sampling rate at the Geomagnetic Observatory Panagjuriste, Bulgaria, along the X and Y components of the geomagnetic field variations, are analyzed. The time evolution of the ULF variations, the local and the global geomagnetic K-indices and the dynamical spectra in the ULF range are presented. It is found that spectral characteristics before 10 UT along the two geomagnetic components have similarities in term of the time of occurrence, the time scale and power. After 10 UT, the results show radical differences in the manifestations of disturbance in the two geomagnetic components in terms of the time scales in which they occur.