Survey of magnetic pulsations at the geosynchronous orbit

Abstract

Magnetic pulsations are Ultra Low Frequency (ULF) electromagnetic waves and are considered to be one of the modes for transfer of energy and momentum from the solar wind to the magnetosphere and different plasma regimes within the magnetosphere. Magnetic pulsations are usually identified using ground based magnetometer measurements and are classified into different categories. In this study, we have used ten years of GOES satellite geo-synchronous magnetic field measurements to identify and characterize magnetic pulsations. Our analysis resulted in 962 clear pulsation events in Pc5, Pi2 and Pc4 bands. Two satellite locations were used in the study, giving a comparison of pulsation events at two different local times. Upon finding a pulsation, a time-frequency spectral analysis was employed to determine the pulsation frequency. Pulsations were found to occur most frequently in the late morning to evening sector, with their time duration following a power law distribution. Frequencies in the 5 to 8 mHz band were the most common, however a broad range of frequencies were found. A possible frequency dependence on magnetic field inclination was found, although more study is needed to be conclusive.