Abstract:
On 27-28 September 2017 at Geomagnetic Observatory Panagjuriste (PAG), Bulgaria the geomagnetic storm – class G2 increasing to G3 was observed. It caused disturbances over the ultra-low frequency (ULF) geomagnetic field variations. The time series of the collected data along the X (north-south), the Y (east-west) and Z (vertical) directions are analyzed. Trough Morlet wavelet analysis the dynamic spectra for the X and the Y components are obtained. They show disturbances strongly corresponding with geomagnetic activity and covers all investigated time scales (1-600s). The two most powerful interferences are recorded on 28 September- 09UTC and 21UTC- along the Y component which strongly correspond with Kp index, but not with local K index. They don’t appear along the other two components. It is found that during the time interval 00-03UTC on 28 September the pulsations are recorded along the X component with periodicity that covers time scales 40-110s and main period about 85s, and they are most likely related to injections of energetic plasma.