Study of variation in the power spectral density of Pc5 pulsations during May 14-18, 2005 geomagnetic storm using SAMBA magnetometer array data

Geomagnetic field data measured by SAMBA magnetometer array were used to study variations in the power spectral density of the ULF waves between 1.7 and 7 mHz associated to Pc5 pulsations during May 12-18, 2005 geomagnetic storm. Statistical analysis of Pc5 power as a function of magnetic local time (MLT), McIlwain parameter (L) and solar wind velocity showed that there is a significant that median power depends strongly on MLT and this dependence is sensitive to the solar wind velocity, L-shall and phase of geomagnetic storm. For SAMBA stations (L between 1.03 and 1.63 Re) the maximum median power is observed in the morning MLT sector for the slow solar wind (Vsw < 500 km/s) and in the midnight sector for the high solar wind (Vsw > 500 km/s). The By-component power peaks at the latitude of the Valdivia station (L=1.23 Re), conversely, the Bx-component power increases monotonically. Nevertheless, these dependencies are sensitive to the storm phase.