摘要：AbstractTo study the activities and the physics of the Earth’s magnetosphere, several types of measurements are made with different kinds of instruments both on earth and in space. Ground based data represent the properties of the solar wind, the Earth’s magnetic field and currents in the magnetosphere. Many of the activities occurring in the magnetosphere are a result of changes in the solar wind.It has been known since the 1860s that the Earth’s magnetic field is fluctuating and during that times the fluctuations are periodical.In this study, a special type of magnetic pulsations in the Earth’s magnetic field called Pi 2 (from MAGDAS stations in Egypt) is investigated and analyzed statistically.We carried out our analysis through two different methods: (i) Fourier transformations and (ii) wavelet power spectrum.The result shows that the Pi 2 observed in the main phase of the geomagnetic storm have larger frequency than those observed in the recovery phase. These results excluded the field line resonance and the plasmapause surface as a possible generation mechanism, and suggest the cavity resonance as a possible generation mechanism of the Pi 2 pulsations at low latitude stations in Egypt.
