Pc3 pulsations during variable IMF conditions

Pc3 geomagnetic field fluctuations detected at low latitude (L'Aquila, Ital y) during the passage of a high velocity solar wind stream, characterized b y variable interplanetary magnetic field conditions, are analyzed. Higher f requency resonant fluctuations and lower frequency phenomena are simultaneo usly observed; the intermittent appearance and the variable frequency of th e longer period modes can be well interpreted in terms of the variable IMF elements; moreover their polarization characteristics are consistent with a n origin related to external waves propagating in antisunward direction. A comparison with simultaneous observations performed at Terra Nova Bay (Anta rctica) provides additional evidence for a clear relationship between the I MF and Pc3 pulsations also at very high latitudes.