Pc5 ULF waves during the geomagnetic storms on 7–8 September 2017 observed in the Indonesian region

Abstract

Pc5 ULF waves have attracted significant attention and been studied through theory, simulation, and observations. To understand the generation mechanisms of ULF waves, one should consider frequency characteristics, solar wind parameters, and geomagnetic activity. Observation on Pc5 magnetic pulsations due to solar wind perturbations at the low latitudes currently has not been widely explored. In this paper, we analyzed the amplitude of Pc5 magnetic pulsations during magnetic storms on 7–8 September 2017. We also investigated the effect of shock in the solar wind on the amplitude of Pc5 magnetic pulsation. We used the magnetometer data of four stations in the Indonesian region, which is located at low latitude, the ACE satellite data, and the Dst index. To extract Pc5 magnetic pulsations, we used the second-order of Butterworth filter with applying the Hamming windowing method. The result shows that the fluctuation in solar wind dynamic pressure triggers the Pc5 pulsations with similar waveforms and the same phase in both components of H and D. Large southward Bz component of the interplanetary magnetic field accompanied by the increase of solar wind dynamic pressure caused the large and long duration of Pc5 pulsation.