Pc3 pulsations during variable IMF conditions

U. Villante, S. Lepidi, P. Francia, M. Vellante, A. Meloni, R. P. Lepping and F. Mariani

Dipartimento de Fisica, Universitá dell'Aquila, L'Aquila, Italy


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

Annales Geophysicae, 17, 490-496, 1999