Pc5 PULSATIONS OBSERVED DURING THE GEOMAGNETIC STORM ON 12 MAY 2021

Abstract

The study of ultra-low frequency (ULF) waves and geomagnetic pulsations plays an important role in better understanding the mechanisms of their generation and spread in the magnetosphere and on the ground. The magnetospheric ULF waves, which provide useful information about the conditions in the solar wind and in the magnetosphere, can be detected on the ground by different types of magnetometers and recorded as geomagnetic pulsations � continuous and irregular. This paper aims to study the characteristics of Pc5 geomagnetic continuous pulsations recorded at mid latitudes during the strong geomagnetic storm (Kp =7) that occurred on May 12, 2021. The sets of time series of data at sampling period 1s, recorded along the three geomagnetic directions (X, Y and Z), are shown and analyzed. A spectral analysis, based on the Morlet Wavelet transform, is applied. It shows powerful geomagnetic disturbances in the Pc5 band (1.7-6.7 mHz) in two-time intervals: 00-02 UTC- before the beginning of the storm and 10-15 UTC- during the storm. Furthermore, the Fast Fourier Transform (FFT) band pass filter is applied to the data series, and Pc5 pulsations are shown. It was concluded that their emergence was correlated with the dynamics of changes in the interplanetary magnetic field (IMF) Bz component, solar wind plasma speed, and flow dynamic pressure.