Summary
Pc3-4 pulsations observed at high-latitudes have been examined for evidence of magnetic field line resonances. Previous studies have suggested that these pulsations are due to harmonics of the lower frequency Pc5 pulsations. We investigated near-conjugate properties of high-latitude Pc3-4 pulsations using magnetometers of the IMAGE array in northern Scandinavia and the fluxgate magnetometer at Davis station, Antarctica. Analysis included comparison of time series, dynamic power spectra, and cross-phase, cross-power and coherence properties between the conjugate points. Our analysis of 11 events from March,1996 suggests that the Pc3-4 pulsations are not standing field line oscillations or harmonics of field line resonances. We discuss two possible mechanisms for their generation; the forced oscillation of field lines and propagation direct to the ionosphere. In both cases the pulsation source is the upstream ion-cyclotron resonance mechanism.