ULF pulsations of Pc 3–4 type were recorded in the ionosphere at several longitudes with the European Incoherent Scatter facility. The analysis of these pulsations needs sophisticated signal processing. We found that a detailed description of these pulsations must be made burst by burst. The characteristic parameters are time, frequency, and space extent. Comparison with ground recordings indicates that only the H component is well related to the ionospheric ion velocity. The ionosphere‐ground relation is discussed in terms of variability of the auroral conductivity and spatial extent.

During 1984 total electron content (TEC) data were gathered from Melbourne, a mid-latitude station, and from Macquarie Island in the southern auroral zone, using the Faraday rotation of geostationary satellite signals. Large-scale fluctuations in the TEC due to auroral activity were observed from Macquarie Island, and some of these disturbances were seen to propagate towards Melbourne with speeds of 200 to 1,000 m/s. Large-scale rapid decreases in TEC were observed during the evening hours of about one third of autumn equinox days studied. These decreases occurred at a geomagnetic latitude of approximately 60øS and could be associated with the main ionospheric trough travelling through the ray path from the satellite to the receiving station.