CHARACTERISTICS OF Pc5 PULSATIONS ACTIVITY AT MID LATITUDES DURING DECEMBER 2019

Abstract

Magnetospheric pulsations and the mechanisms underlying their generation are topics under active studies. The Pc5 (f =1.7�6.7 mHz) geomagnetic continuous pulsations, recorded at mid latitudes (L =1.6) during December 2019, with a low level of geomagnetic activity, are analyzed and discussed in this paper. The data sets of the series on geomagnetic field variations recorded at Panagjuriste Geomagnetic Observatory in Bulgaria are analyzed. The spectral characteristics of the pulsations were determined by Continuous Wavelet Analysis (CWT). It is demonstrated that Pc5 pulsation activity appears with all ranges of periods (140-600s) on December 6, 8, and 18, 2019, at time intervals of 02-17 UTC, 14-20 UTC, and 00-16 UTC, respectively. Then, the solar wind (SW) plasma speed, the flow dynamic pressure, and the geomagnetic index Kp are computed for every case of recorded Pc5 pulsations. It is suggested that recorded continuous pulsations in the Pc5 range are due to step-like or sudden increases in solar wind oscillations and variations of the flow dynamic pressure, which precede the appearance of pulsations and drive compressional magnetic field variations in the magnetosphere.