SIMULTANEOUS OBSERVATIONS OF PC-5 PULSATIONS BY VHF RADARS SPACED 10 HOURS IN MLT

Long-period Pc 5 pulsations have been recorded simultaneously by VHF radars operating in Scandinavia and New Zealand. The radars are in opposite hemispheres and are spaced about 10 hours in local time. Those pulsations analyzed are either of the 'quasi-regular' variety or take the form of damped trains that often follow magnetic sudden commencements. An estimation of equatorial plane ion mass densities shows azimuthal variations attributable to several possible causes, including the presence of localized density gradients or a significant proportion of heavy ions. A transient-type pulsation shows the effect of the two radars being directed inside and outside the plasmapause, and a longer-lasting event suggests a monochromatic drive of different period on the dawn and dusk flanks of the magnetosphere.