Global Pc5 event during 29–31 October 2003 magnetic storm Original Research Article

On 30–31 October 2003 magnetic observatories over the whole Earth surface observed a very strong and enduring long-period ULF activity during the recovery phase of the magnetic storm, which had begun a day before, at 0611 UT on October 29th, 2003. Amplitude of oscillations in the Pc5 frequency range was as high as 150 nT at mid-latitude stations. We use magnetic data from INTERMAGNET database, IMAGE magnetometer network, and GOES-10,-12 satellites to study this event. According to IMAGE data, Pc5 polarization pattern along a meridian does not correspond to that expected for field line resonance model. Latitude profile of the horizontal components has its maximum at auroral latitudes. At medium latitudes, Pc5 were observed at all local time sectors simultaneously with larger amplitude at prenoon or noon hours. Boundary layer instability is suggested as a probable source of the global magnetospheric wave activity. Possible consequences of large amplitude oscillations for charged particle acceleration owing to various wave-particle interaction mechanisms are discussed.