The coherence scale length of band‐limited Pc3 pulsations in the ionosphere

Band‐limited Pc‐3 pulsations were observed on one day with pulsation magnetometers, photometers and in VLF activity at South Pole and simultaneously, electric field pulsations were observed in the ionospheric cusp using the PACE HF‐Radar located at Halley Station, Antarctica. The electric field pulsations were observed by the radar on open magnetic field lines, which were likely to be connected more directly to the source region (upstream of the foreshock) of the activity than the magnetic pulsations, which were observed on closed magnetic field lines. The electric field pulsations were found to have a coherence scale length of around 30–60 km, significantly less than the upper limit that can be determined from magnetometer measurements.